Extractions of polarized and unpolarized parton distribution functions
Jimenez-Delgado, Pedro
2014-01-01
An overview of our ongoing extractions of parton distribution functions of the nucleon is given. First JAM results on the determination of spin-dependent parton distribution functions from world data on polarized deep-inelastic scattering are presented first, and followed by a short report on the status of the JR unpolarized parton distributions. Different aspects of PDF analysis are briefly discussed, including effects of the nuclear structure of targets, target-mass corrections and higher twist contributions to the structure functions.
Unbiased determination of polarized parton distributions and their uncertainties
NASA Astrophysics Data System (ADS)
Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2013-09-01
We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations.
First JAM results on the determination of polarized parton distributions
Jimenez-Delgado, Pedro
2013-04-01
The Jefferson Lab Angular Momentum (JAM) collaboration is a new initiative aimed to the study of the angular-momentum-dependent structure of the nucleon. First results on the determination of spin-dependent parton distribution functions from world data on polarized deep-inelastic scattering will be presented and compared with previous determinations from other groups. Different aspects of global QCD analysis will be discussed, including effects due to nuclear structure, higher twist, and target-mass corrections, as well as the impact of different data selections.
First JAM results on the determination of polarized parton distributions
Accardi, Alberto; Jimenez-Delgado, Pedro; Melnitchouk, Wally
2014-01-01
The Jefferson Lab Angular Momentum (JAM) Collaboration is a new initiative to study the angular momentum dependent structure of the nucleon. First results on the determination of spin-dependent parton distribution functions at intermediate and large x from world data on polarized deep-inelastic scattering are presented. Different aspects of global QCD analysis are discussed, including the effects of nuclear structure of deuterium and {sup 3}He targets, target mass corrections and higher twist contributions to the g{sub 1} and g{sub 2} structure functions.
How large is the gluon polarization in the statistical parton distributions approach?
Soffer, Jacques; Bourrely, Claude; Buccella, Franco
2015-04-10
We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.
The parton distributions in nuclei and in polarized nucleons
Close, F.E.
1988-01-01
The emerging information was reviewed on the way quark and anti-quark, and gluon distributions are modified in nuclei relative to free nucleons. Some implications of the recent data on polarized leptoproduction are discussed. 27 refs., 6 figs.
Nuclear Parton Distribution Functions
Schienbein, I.; Yu, J.-Y.; Keppel, Cynthia; Morfin, Jorge; Olness, F.; Owens, J.F.
2009-01-01
We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a chi^2 analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x_Bj-dependent and Q^2-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x_Bj, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.
Nuclear Parton Distribution Functions
I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens
2009-06-01
We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.
Unintegrated double parton distributions - A summary
NASA Astrophysics Data System (ADS)
Golec-Biernat, Krzysztof; Staśto, Anna
2017-03-01
We present main elements of the construction of unintegrated double parton distribution functions which depend on transverse momenta of partons. We follow the method proposed by Kimber, Martin and Ryskin for a construction of unintegrated single parton distributions from the standard parton distribution functions.
Medium Effects in Parton Distributions
William Detmold, Huey-Wen Lin
2011-12-01
A defining experiment of high-energy physics in the 1980s was that of the EMC collaboration where it was first observed that parton distributions in nuclei are non-trivially related to those in the proton. This result implies that the presence of the nuclear medium plays an important role and an understanding of this from QCD has been an important goal ever since Here we investigate analogous, but technically simpler, effects in QCD and examine how the lowest moment of the pion parton distribution is modified by the presence of a Bose-condensed gas of pions or kaons.
Generalized parton distributions in nuclei
Vadim Guzey
2009-12-01
Generalized parton distributions (GPDs) of nuclei describe the distribution of quarks and gluons in nuclei probed in hard exclusive reactions, such as e.g. deeply virtual Compton scattering (DVCS). Nuclear GPDs and nuclear DVCS allow us to study new aspects of many traditional nuclear effects (nuclear shadowing, EMC effect, medium modifications of the bound nucleons) as well as to access novel nuclear effects. In my talk, I review recent theoretical progress in the area of nuclear GPDs.
Structure functions and parton distributions
Martin, A.D.; Stirling, W.J.; Roberts, R.G.
1995-07-01
The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.
Momentum transfer dependence of generalized parton distributions
NASA Astrophysics Data System (ADS)
Sharma, Neetika
2016-11-01
We revisit the model for parametrization of the momentum dependence of nucleon generalized parton distributions in the light of recent MRST measurements of parton distribution functions (A.D. Martin et al., Eur. Phys. J. C 63, 189 (2009)). Our parametrization method with a minimum set of free parameters give a sufficiently good description of data for Dirac and Pauli electromagnetic form factors of proton and neutron at small and intermediate values of momentum transfer. We also calculate the GPDs for up- and down-quarks by decomposing the electromagnetic form factors for the nucleon using the charge and isospin symmetry and also study the evolution of GPDs to a higher scale. We further investigate the transverse charge densities for both the unpolarized and transversely polarized nucleon and compare our results with Kelly's distribution.
Accardi, Alberto; Owens, Jeff F.
2013-07-01
Three new sets of next-to-leading order parton distribution functions (PDFs) are presented, determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep-inelastic scattering data at large x and low Q^2, and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF compared with previous fits. Applications to weak boson production at colliders are also discussed.
NASA Astrophysics Data System (ADS)
Zhu, Jiacai; Ma, Bo-Qiang
2010-12-01
We show that the polarized proton-antiproton Drell-Yan process is ideal to probe the pretzelosity distribution (h1T⊥), which is one of the new transverse-momentum-dependent parton distributions of the nucleon. We present predictions of the cos(2ϕ+ϕa-ϕb) asymmetry in the transversely polarized proton-antiproton Drell-Yan process at PAX kinematics and find that the results are significantly larger compared with those of the sin(3ϕh-ϕS) asymmetry in the semi-inclusive deep inelastic scattering process at HERMES, COMPASS, and JLab kinematics. We conclude that the cos(2ϕ+ϕa-ϕb) asymmetry in the PAX experiment can probe the new physical quantity of the pretzelosity distribution.
Jet correlations from unintegrated parton distributions
Hautmann, F.; Jung, H.
2008-10-13
Transverse-momentum dependent parton distributions can be introduced gauge-invariantly in QCD from high-energy factorization. We discuss Monte Carlo applications of these distributions to parton showers and jet physics, with a view to the implications for the Monte Carlo description of complex hadronic final states with multiple hard scales at the LHC.
Parton distributions with LHC data
NASA Astrophysics Data System (ADS)
Ball, Richard D.; Bertone, Valerio; Carrazza, Stefano; Deans, Christopher S.; Del Debbio, Luigi; Forte, Stefano; Guffanti, Alberto; Hartland, Nathan P.; Latorre, José I.; Rojo, Juan; Ubiali, Maria; Nnpdf Collaboration
2013-02-01
We present the first determination of parton distributions of the nucleon at NLO and NNLO based on a global data set which includes LHC data: NNPDF2.3. Our data set includes, besides the deep inelastic, Drell-Yan, gauge boson production and jet data already used in previous global PDF determinations, all the relevant LHC data for which experimental systematic uncertainties are currently available: ATLAS and LHCb W and Z rapidity distributions from the 2010 run, CMS W electron asymmetry data from the 2011 run, and ATLAS inclusive jet cross-sections from the 2010 run. We introduce an improved implementation of the FastKernel method which allows us to fit to this extended data set, and also to adopt a more effective minimization methodology. We present the NNPDF2.3 PDF sets, and compare them to the NNPDF2.1 sets to assess the impact of the LHC data. We find that all the LHC data are broadly consistent with each other and with all the older data sets included in the fit. We present predictions for various standard candle cross-sections, and compare them to those obtained previously using NNPDF2.1, and specifically discuss the impact of ATLAS electroweak data on the determination of the strangeness fraction of the proton. We also present collider PDF sets, constructed using only data from HERA, the Tevatron and the LHC, but find that this data set is neither precise nor complete enough for a competitive PDF determination.
Unraveling hadron structure with generalized parton distributions
Andrei Belitsky; Anatoly Radyushkin
2004-10-01
The recently introduced generalized parton distributions have emerged as a universal tool to describe hadrons in terms of quark and gluonic degrees of freedom. They combine the features of form factors, parton densities and distribution amplitudes - the functions used for a long time in studies of hadronic structure. Generalized parton distributions are analogous to the phase-space Wigner quasi-probability function of non-relativistic quantum mechanics which encodes full information on a quantum-mechanical system. We give an extensive review of main achievements in the development of this formalism. We discuss physical interpretation and basic properties of generalized parton distributions, their modeling and QCD evolution in the leading and next-to-leading orders. We describe how these functions enter a wide class of exclusive reactions, such as electro- and photo-production of photons, lepton pairs, or mesons.
Generalized Valon Model for Double Parton Distributions
NASA Astrophysics Data System (ADS)
Broniowski, Wojciech; Ruiz Arriola, Enrique; Golec-Biernat, Krzysztof
2016-06-01
We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.
Deeply exclusive processes and generalized parton distributions
Marc Vanderhaegen
2005-02-01
We discuss how generalized parton distributions (GPDs) enter into hard exclusive processes, and focuses on the links between GPDs and elastic nucleon form factors. These links, in the form of sum rules, represent powerful constraints on parameterizations of GPDs. A Regge parameterization for the GPDs at small momentum transfer -t is extended to the large-t region and it is found to catch the basic features of proton and neutron electromagnetic form factor data. This parameterization allows to estimate the quark contribution to the nucleon spin. It is furthermore discussed how these GPDs at large-t enter into two-photon exchange processes and resolve the discrepancy between Rosenbluth and polarization experiments of elastic electron nucleon scattering.
Transverse-momentum-dependent parton distributions (TMDs)
Bacchetta, Alessandro
2011-10-24
Transverse-momentum-dependent parton distributions (TMDs) provide three-dimensional images of the partonic structure of the nucleon in momentum space. We made impressive progress in understanding TMDs, both from the theoretical and experimental point of view. This brief overview on TMDs is divided in two parts: in the first, an essential list of achievements is presented. In the second, a selection of open questions is discussed.
Constraints on parton distribution from CDF
Bodek, A.; CDF Collaboration
1995-10-01
The asymmetry in W{sup -} - W{sup +} production in p{bar p} collisions and Drell-Yan data place tight constraints on parton distributions functions. The W asymmetry data constrain the slope of the quark distribution ratio d(x)/u(x) in the x range 0.007-0.27. The published W asymmetry results from the CDF 1992.3 data ({approx} 20 pb{sup -1}) greatly reduce the systematic error originating from the choice of PDF`s in the W mass measurement at CDF. These published results have also been included in the CTEQ3, MRSA, and GRV94 parton distribution fits. These modern parton distribution functions axe still in good agreement with the new 1993-94 CDF data({approx} 108 pb{sup -1} combined). Preliminary results from CDF for the Drell-Yan cross section in the mass range 11-350 GeV/c{sup 2} are discussed.
The parton distribution function library
Plothow-Besch, H.
1995-07-01
This article describes an integrated package of Parton Density Functions called PDFLIB which has been added to the CERN Program Library Pool W999 and is labelled as W5051. In this package all the different sets of parton density functions of the Nucleon, Pion and the Photon which are available today have been put together. All these sets have been combined in a consistent way such that they all have similar calling sequences and no external data files have to be read in anymore. A default set has been prepared, although those preferring their own set or wanting to test a new one may do so within the package. The package also offers a program to calculate the strong coupling constant {alpha}, to first or second order. The correct {Lambda}{sub QCD} associated to the selected set of structure functions and the number of allowed flavours with respect to the given Q{sup 2} is automatically used in the calculation. The selection of sets, the program parameters as well as the possibilities to modify the defaults and to control errors occurred during execution are described.
Progress in the dynamical parton distributions
Jimenez-Delgado, Pedro
2012-06-01
The present status of the (JR) dynamical parton distribution functions is reported. Different theoretical improvements, including the determination of the strange sea input distribution, the treatment of correlated errors and the inclusion of alternative data sets, are discussed. Highlights in the ongoing developments as well as (very) preliminary results in the determination of the strong coupling constant are presented.
Higher twist parton distributions from light-cone wave functions
Braun, V. M.; Lautenschlager, T.; Pirnay, B.; Manashov, A. N.
2011-05-01
We explore the possibility to construct higher-twist parton distributions in a nucleon at some low reference scale from convolution integrals of the light-cone wave functions (WFs). To this end we introduce simple models for the four-particle nucleon WFs involving three valence quarks and a gluon with total orbital momentum zero, and estimate their normalization (WF at the origin) using QCD sum rules. We demonstrate that these WFs provide one with a reasonable description of both polarized and unpolarized parton densities at large values of the Bjorken variable x{>=}0.5. Twist-three parton distributions are then constructed as convolution integrals of qqqg and the usual three-quark WFs. The cases of the polarized structure function g{sub 2}(x,Q{sup 2}) and single transverse spin asymmetries are considered in detail. We find that the so-called gluon pole contribution to twist-three distributions relevant for single spin asymmetry vanishes in this model, but is generated perturbatively at higher scales by the evolution, in the spirit of Glueck-Reya-Vogt parton distributions.
Generalized Parton Distributions: Visions, Basics, and Realities
NASA Astrophysics Data System (ADS)
Müller, D.
2014-06-01
An introductory to generalized parton distributions (GDPs) is given which emphasizes their spectral property and its uses as well as the equivalence of various GDP representations. Furthermore, the status of the theory and phenomenology of hard exclusive processes is shortly reviewed.
Nonperturbative evolution of parton quasi-distributions
NASA Astrophysics Data System (ADS)
Radyushkin, A. V.
2017-04-01
Using the formalism of parton virtuality distribution functions (VDFs) we establish a connection between the transverse momentum dependent distributions (TMDs) F (x , k⊥2) and quasi-distributions (PQDs) Q (y ,p3) introduced recently by X. Ji for lattice QCD extraction of parton distributions f (x). We build models for PQDs from the VDF-based models for soft TMDs, and analyze the p3 dependence of the resulting PQDs. We observe a strong nonperturbative evolution of PQDs for small and moderately large values of p3 reflecting the transverse momentum dependence of TMDs. Thus, the study of PQDs on the lattice in the domain of strong nonperturbative effects opens a new perspective for investigation of the 3-dimensional hadron structure.
Generalized parton distributions and exclusive processes
Guzey, Vadim
2013-10-01
In last fifteen years, GPDs have emerged as a powerful tool to reveal such aspects of the QCD structure of the nucleon as: - 3D parton correlations and distributions; - spin content of the nucleon. Further advances in the field of GPDs and hard exclusive processes rely on: - developments in theory and new methods in phenomenology such as new flexible parameterizations, neural networks, global QCD fits - new high-precision data covering unexplored kinematics: JLab at 6 and 12 GeV, Hermes with recoil detector, Compass, EIC. This slide-show presents: Nucleon structure in QCD, particularly hard processes, factorization and parton distributions; and a brief overview of GPD phenomenology, including basic properties of GPDs, GPDs and QCD structure of the nucleon, and constraining GPDs from experiments.
Parton distribution benchmarking with LHC data
NASA Astrophysics Data System (ADS)
Ball, Richard D.; Carrazza, Stefano; Del Debbio, Luigi; Forte, Stefano; Gao, Jun; Hartland, Nathan; Huston, Joey; Nadolsky, Pavel; Rojo, Juan; Stump, Daniel; Thorne, Robert S.; Yuan, C.-P.
2013-04-01
We present a detailed comparison of the most recent sets of NNLO PDFs from the ABM, CT, HERAPDF, MSTW and NNPDF collaborations. We compare parton distributions at low and high scales and parton luminosities relevant for LHC phenomenology. We study the PDF dependence of LHC benchmark inclusive cross sections and differential distributions for electroweak boson and jet production in the cases in which the experimental covariance matrix is available. We quantify the agreement between data and theory by computing the χ 2 for each data set with all the various PDFs. PDF comparisons are performed consistently for common values of the strong coupling. We also present a benchmark comparison of jet production at the LHC, comparing the results from various available codes and scale settings. Finally, we discuss the implications of the updated NNLO PDF sets for the combined PDF+ α s uncertainty in the gluon fusion Higgs production cross section.
Access to generalized parton distributions at COMPASS
Nowak, Wolf-Dieter
2015-04-10
A brief experimentalist's introduction to Generalized Parton Distributions (GPDs) is given. Recent COMPASS results are shown on transverse target-spin asymmetries in hard exclusive ρ{sup 0} production and their interpretation in terms of a phenomenological model as indication for chiral-odd, transverse GPDs is discussed. For deeply virtual Compton scattering, it is briefly outlined how to access GPDs and projections are shown for future COMPASS measurements.
Generalized parton distributions and Deeply Virtual Compton Scattering on proton at CLAS
R. De Masi
2007-12-01
Two measurements of target and beam spin asymmetries for the reaction ep→epγ were performed with CLAS at Jefferson Laboratory. Polarized 5.7 GeV electrons were impinging on a longitudinally polarized ammonia and liquid hydrogen target respectively. These measurements are sensitive to Generalized Parton Distributions. Sizable sin phi azimuthal angular dependences were observed in both experiments, indicating the dominance of leading twist terms and the possibility of extracting combinations of Generalized Parton Distributions on the nucleon.
First moments of nucleon generalized parton distributions
Wang, P.; Thomas, A. W.
2010-06-01
We extrapolate the first moments of the generalized parton distributions using heavy baryon chiral perturbation theory. The calculation is based on the one loop level with the finite range regularization. The description of the lattice data is satisfactory, and the extrapolated moments at physical pion mass are consistent with the results obtained with dimensional regularization, although the extrapolation in the momentum transfer to t=0 does show sensitivity to form factor effects, which lie outside the realm of chiral perturbation theory. We discuss the significance of the results in the light of modern experiments as well as QCD inspired models.
Parton distributions in nuclei: Quagma or quagmire
Close, F.E.
1988-01-01
The emerging information on the way quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed. Particular emphasis is placed on Drell-Yan and /psi/ production on nuclei and caution against premature use of these as signals for quagma in heavy-ion collisions. If we are to identify the formation of quark-gluon plasma in heavy-ion collisions by changes in the production rates for /psi/ relative to Drell-Yan lepton pairs, then it is important that we first understand the ''intrinsic'' changes in parton distributions in nuclei relative to free nucleons. So, emerging knowledge on how quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed, and the emerging theoretical concensus is briefly summarized.
Generalized parton distributions from deep virtual compton scattering at CLAS
Guidal, M.
2010-04-24
Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less
Delineating the polarized and unpolarized partonic structure of the nucleon
Jimenez-Delgado, Pedro
2015-03-01
Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.
Delineating the polarized and unpolarized partonic structure of the nucleon
Jimenez-Delgado, Pedro
2015-03-01
Our latest results on the extraction of parton distribution functions of the nucleon are reported. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are given, including a careful treatment of hadronic and nuclear corrections, as well as results on the impact of present and future data in our understanding of the spin of the nucleon.
Nuclear modifications of Parton Distribution Functions
NASA Astrophysics Data System (ADS)
Adeluyi, Adeola Adeleke
This dissertation addresses a central question of modern nuclear physics: how does the behavior of fundamental degrees of freedom (quarks and gluons) change in the nuclear environment? This is an important aspect of experimental studies at current facilities such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Laboratory (JLAB). It is also highly relevant to planned experimental efforts at the Large Hadron Collider (LHC) and the future Electron Ion Collider (EIC). All these facilities probe matter via collisions involving nuclei; thus complications arise due to the presence of the attendant nuclear medium. Theoretical efforts to understand and interpret experimental results from such collisions are therefore largely dependent on the resolution of this question. The development of nuclear physics demonstrates that theoretical description is most efficient in terms of the effective degrees of freedom relevant to the scale (energy) being probed. Thus at low energies, nuclei are described as bound states of protons and neutrons (nucleons). At higher energies, the nucleons are no longer elementary, but are revealed to possess an underlying substructure: they are made up of quarks and gluons, collectively termed partons. The mometum distributions of these partons in the nucleon are referred to as Parton Distribution Functions (PDFs). Parton distributions can be determined from experimental measurements of structure functions. The ratio of nuclear structure functions to nucleon structure functions (generically referred to as nuclear ratio) is a measure of the nuclear modifications of the free nucleon PDFs. Thus a study of the nuclear ratio suffices to gain an understanding of nuclear modifications. In this dissertation we aim to describe theoretically nuclear modifications in a restricted region where the nuclear ratio is less than unity, the so
New model for nucleon generalized parton distributions
Radyushkin, Anatoly V.
2014-01-01
We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.
Quasi parton distributions and the gradient flow
Monahan, Christopher; Orginos, Kostas
2017-03-22
We propose a new approach to determining quasi parton distribution functions (PDFs) from lattice quantum chromodynamics. By incorporating the gradient flow, this method guarantees that the lattice quasi PDFs are finite in the continuum limit and evades the thorny, and as yet unresolved, issue of the renormalization of quasi PDFs on the lattice. In the limit that the flow time is much smaller than the length scale set by the nucleon momentum, the moments of the smeared quasi PDF are proportional to those of the lightfront PDF. Finally, we use this relation to derive evolution equations for the matching kernelmore » that relates the smeared quasi PDF and the light-front PDF.« less
Nucleon Generalized Parton Distributions from Full Lattice QCD
Robert Edwards; Philipp Haegler; David Richards; John Negele; Konstantinos Orginos; Wolfram Schroers; Jonathan Bratt; Andrew Pochinsky; Michael Engelhardt; George Fleming; Bernhard Musch; Dru Renner
2007-07-03
We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N_f=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)^3.
Improved quasi parton distribution through Wilson line renormalization
NASA Astrophysics Data System (ADS)
Chen, Jiunn-Wei; Ji, Xiangdong; Zhang, Jian-Hui
2017-02-01
Recent developments showed that hadron light-cone parton distributions could be directly extracted from spacelike correlators, known as quasi parton distributions, in the large hadron momentum limit. Unlike the normal light-cone parton distribution, a quasi parton distribution contains ultraviolet (UV) power divergence associated with the Wilson line self energy. We show that to all orders in the coupling expansion, the power divergence can be removed by a "mass" counterterm in the auxiliary z-field formalism, in the same way as the renormalization of power divergence for an open Wilson line. After adding this counterterm, the quasi quark distribution is improved such that it contains at most logarithmic divergences. Based on a simple version of discretized gauge action, we present the one-loop matching kernel between the improved non-singlet quasi quark distribution with a lattice regulator and the corresponding quark distribution in dimensional regularization.
Nuclear parton distributions and the Drell-Yan process
NASA Astrophysics Data System (ADS)
Kulagin, S. A.; Petti, R.
2014-10-01
We study the nuclear parton distribution functions on the basis of our recently developed semimicroscopic model, which takes into account a number of nuclear effects including nuclear shadowing, Fermi motion and nuclear binding, nuclear meson-exchange currents, and off-shell corrections to bound nucleon distributions. We discuss in detail the dependencies of nuclear effects on the type of parton distribution (nuclear sea vs valence), as well as on the parton flavor (isospin). We apply the resulting nuclear parton distributions to calculate ratios of cross sections for proton-induced Drell-Yan production off different nuclear targets. We obtain a good agreement on the magnitude, target and projectile x, and the dimuon mass dependence of proton-nucleus Drell-Yan process data from the E772 and E866 experiments at Fermilab. We also provide nuclear corrections for the Drell-Yan data from the E605 experiment.
Nucleon parton distributions in a light-front quark model
NASA Astrophysics Data System (ADS)
Gutsche, Thomas; Lyubovitskij, Valery E.; Schmidt, Ivan
2017-02-01
Continuing our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity-independent and the helicity-dependent parton distributions, analytically matching the results of global fits at the initial scale μ ˜ 1 GeV; they also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions q_v(x) and δ q_v(x). Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN).
Deeply Virtual Exclusive Processes and Generalized Parton Distributions
,
2011-06-01
The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.
Reconstruction of Monte Carlo replicas from Hessian parton distributions
NASA Astrophysics Data System (ADS)
Hou, Tie-Jiun; Gao, Jun; Huston, Joey; Nadolsky, Pavel; Schmidt, Carl; Stump, Daniel; Wang, Bo-Ting; Xie, Ke Ping; Dulat, Sayipjamal; Pumplin, Jon; Yuan, C. P.
2017-03-01
We explore connections between two common methods for quantifying the uncertainty in parton distribution functions (PDFs), based on the Hessian error matrix and Monte-Carlo sampling. CT14 parton distributions in the Hessian representation are converted into Monte-Carlo replicas by a numerical method that reproduces important properties of CT14 Hessian PDFs: the asymmetry of CT14 uncertainties and positivity of individual parton distributions. The ensembles of CT14 Monte-Carlo replicas constructed this way at NNLO and NLO are suitable for various collider applications, such as cross section reweighting. Master formulas for computation of asymmetric standard deviations in the Monte-Carlo representation are derived. A correction is proposed to address a bias in asymmetric uncertainties introduced by the Taylor series approximation. A numerical program is made available for conversion of Hessian PDFs into Monte-Carlo replicas according to normal, log-normal, and Watt-Thorne sampling procedures.
The role of the input scale in parton distribution analyses
Pedro Jimenez-Delgado
2012-08-01
A first systematic study of the effects of the choice of the input scale in global determinations of parton distributions and QCD parameters is presented. It is shown that, although in principle the results should not depend on these choices, in practice a relevant dependence develops as a consequence of what is called procedural bias. This uncertainty should be considered in addition to other theoretical and experimental errors, and a practical procedure for its estimation is proposed. Possible sources of mistakes in the determination of QCD parameter from parton distribution analysis are pointed out.
Concurrent approaches to Generalized Parton Distribution modeling: the pion's case
NASA Astrophysics Data System (ADS)
Chouika, N.; Mezrag, C.; Moutarde, H.; Rodríguez-Quintero, J.
2017-03-01
The concept of Generalized Parton Distributions promises an understanding of the generation of the charge, spin, and energy-momentum structure of hadrons by quarks and gluons. Forthcoming measurements with unprecedented accuracy at Jefferson Lab and at CERN will challenge our quantitative description of the three-dimensional structure of hadrons. To fully exploit these future measurements, new tools and models are currently being developed. We explain the difficulties of Generalized Parton Distribution modeling, and present some recent progresses. In particular we describe the symmetry-preserving Dyson-Schwinger and Bethe-Salpeter framework. We also discuss various equivalent parameterizations and sketch how to combine them to obtain models satisfying a priori all required theoretical constraints. At last we explain why these developments naturally fit in a versatile software framework, named PARTONS, dedicated to the theory and phenomenology of GPDs.
Transverse momentum dependent (TMD) parton distribution functions: Status and prospects*
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, Ian I.; ...
2015-01-01
In this study, we review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum qT spectra of Higgs and vector bosons for low qT, and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present the application of a new tool, TMDLIB, to parton density fits and parameterizations.
Parton distribution functions in Monte Carlo factorisation scheme
NASA Astrophysics Data System (ADS)
Jadach, S.; Płaczek, W.; Sapeta, S.; Siódmok, A.; Skrzypek, M.
2016-12-01
A next step in development of the KrkNLO method of including complete NLO QCD corrections to hard processes in a LO parton-shower Monte Carlo is presented. It consists of a generalisation of the method, previously used for the Drell-Yan process, to Higgs-boson production. This extension is accompanied with the complete description of parton distribution functions in a dedicated, Monte Carlo factorisation scheme, applicable to any process of production of one or more colour-neutral particles in hadron-hadron collisions.
Recent progress in the statistical approach of parton distributions
Soffer, Jacques
2011-07-15
We recall the physical features of the parton distributions in the quantum statistical approach of the nucleon. Some predictions from a next-to-leading order QCD analysis are compared to recent experimental results. We also consider their extension to include their transverse momentum dependence.
Parton Distributions in the pion from lattice QCD
W. Detmold; Wally Melnitchouk; Anthony Thomas
2003-03-01
We analyze the moments of parton distribution functions in the pion calculated in lattice QCD, paying particular attention to their chiral extrapolation. Using the lowest three non-trivial moments calculated on the lattice, we assess the accuracy with which the x-dependence of both the valence and sea quark distributions in the pion can be extracted. The resulting valence quark distributions at the physical pion mass are in fair agreement with existing Drell-Yan data, but the statistical errors are such that one cannot yet confirm (or rule out) the large-x behavior expected from hadron helicity conservation in perturbative QCD. One can expect, however, that the next generation of calculations in lattice QCD will allow one to extract parton distributions with a level of accuracy comparable with current experiments.
Deeply Pseudoscalar Meson Electroproduction with CLAS and Generalized Parton Distributions
Guidal, Michel; Kubarovsky, Valery P.
2015-06-01
We discuss the recent data of exclusive $\\pi^0$ (and $\\pi^+$) electroproduction on the proton obtained by the CLAS collaboration at Jefferson Lab. It is observed that the cross sections, which have been decomposed in $\\sigma_T+\\epsilon\\sigma_L$, $\\sigma_{TT}$ and $\\sigma_{LT}$ structure functions, are dominated by transverse amplitude contributions. The data can be interpreted in the Generalized Parton Distribution formalism provided that one includes helicity-flip transversity GPDs.
Generalized Parton Distributions, Analyticity and Formfactors
Teryaev, O. V
2008-10-13
The QCD factorization for hard exclusive amplitudes is compared with their crossing and analytic properties. The crucial role is played by their mathematical structure described by Radon and Abel transforms, leading to 'holographic' property of GPDs at LO. These transforms are very different in the even- and odd-dimensional spaces, the latter case related to 'creation' GPDs describing, say, the deuteron breakup. The bounds implied by crossing and analyticity for the angular distributions in two-photon processes are obtained. The contributions of different types of QCD factorization and duality between them are considered. The relations of GPDs to (gravitational) formfactors, equivalence principle (EP) and its extension (EEP) are analyzed. EEP is also considered for the case of vector mesons, showing the possible link with AdS/QCD correspondence.
Transverse momentum dependent (TMD) parton distribution functions: Status and prospects*
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, Ian I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F. A.; Cherednikov, I. O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Grados Luyando, J.; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J. P.; Lykasov, G.; Madrigal Martinez, J. D.; Mulders, P. J.; Nocera, E. R.; Petreska, E.; Pisano, C.; Placakyte, R.; Radescu, V.; Radici, M.; Schnell, G.; Signori, A.; Szymanowski, L.; Taheri Monfared, S.; Van der Veken, F. F.; van Haevermaet, H. J.; Van Mechelen, P.; Vladimirov, A. A.; Wallon, S.
2015-01-01
In this study, we review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q_{T} spectra of Higgs and vector bosons for low q_{T}, and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present the application of a new tool, TMD_{LIB}, to parton density fits and parameterizations.
Nuclear Parton Distributions with the LHeC
NASA Astrophysics Data System (ADS)
Klein, Max
2016-03-01
Nuclear parton distributions are far from being known today because of an infant experimental base. Based on design studies of the LHeC and using new simulations, of the inclusive neutral and charged current cross section measurements and of the strange, charm and beauty densities in nuclei, it is demonstrated how that energy frontier electron-ion collider would unfold the complete set of nuclear PDFs in a hugely extended kinematic range of deep inelastic scattering, extending in Bjorken x down to values near to 10-6 in the perturbative domain. Together with a very precise and complete set of proton PDFs, the LHeC nPDFs will thoroughly change the theoretical understanding of parton dynamics and structure inside hadrons.
Pion and kaon valence-quark parton distribution functions
Nguyen, Trang; Bashir, Adnan; Roberts, Craig D.; Tandy, Peter C.
2011-06-15
A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
Pion and kaon valence-quark parton distribution functions.
Nguyen, T.; Bashir, A.; Roberts, C. D.; Tandy, P. C.
2011-06-16
A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
Parton distributions in the LHC era: MMHT 2014 PDFs.
Harland-Lang, L A; Martin, A D; Motylinski, P; Thorne, R S
We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the 'MSTW2008' parton sets, but they are obtained within the same basic framework. We include a variety of new data sets, from the LHC, updated Tevatron data and the HERA combined H1 and ZEUS data on the total and charm structure functions. We also improve the theoretical framework of the previous analysis. These new PDFs are compared to the 'MSTW2008' parton sets. In most cases the PDFs, and the predictions, are within one standard deviation of those of MSTW2008. The major changes are the [Formula: see text] valence quark difference at small [Formula: see text] due to an improved parameterisation and, to a lesser extent, the strange quark PDF due to the effect of certain LHC data and a better treatment of the [Formula: see text] branching ratio. We compare our MMHT PDF sets with those of other collaborations; in particular with the NNPDF3.0 sets, which are contemporary with the present analysis.
Parton distributions in the LHC era: MMHT 2014 PDFs
NASA Astrophysics Data System (ADS)
Harland-Lang, L. A.; Martin, A. D.; Motylinski, P.; Thorne, R. S.
2015-05-01
We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the `MSTW2008' parton sets, but they are obtained within the same basic framework. We include a variety of new data sets, from the LHC, updated Tevatron data and the HERA combined H1 and ZEUS data on the total and charm structure functions. We also improve the theoretical framework of the previous analysis. These new PDFs are compared to the `MSTW2008' parton sets. In most cases the PDFs, and the predictions, are within one standard deviation of those of MSTW2008. The major changes are the valence quark difference at small due to an improved parameterisation and, to a lesser extent, the strange quark PDF due to the effect of certain LHC data and a better treatment of the branching ratio. We compare our MMHT PDF sets with those of other collaborations; in particular with the NNPDF3.0 sets, which are contemporary with the present analysis.
Transverse Momentum-Dependent Parton Distributions From Lattice QCD
Michael Engelhardt, Bernhard Musch, Philipp Haegler, Andreas Schaefer
2012-12-01
Starting from a definition of transverse momentum-dependent parton distributions for semi-inclusive deep inelastic scattering and the Drell-Yan process, given in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection, a scheme to determine such observables in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are presented, focusing in particular on their dependence on the staple extent and the Collins-Soper evolution parameter.
Iterative Monte Carlo analysis of spin-dependent parton distributions
Sato, Nobuo; Melnitchouk, Wally; Kuhn, Sebastian E.; ...
2016-04-05
We present a comprehensive new global QCD analysis of polarized inclusive deep-inelastic scattering, including the latest high-precision data on longitudinal and transverse polarization asymmetries from Jefferson Lab and elsewhere. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to a reduction in the PDF errors for the valence and sea quarks, as well as in the gluon polarization uncertainty at x ≳ 0.1. Furthermore, the study also provides the first determination of the flavor-separated twist-3 PDFsmore » and the d2 moment of the nucleon within a global PDF analysis.« less
Iterative Monte Carlo analysis of spin-dependent parton distributions
Sato, Nobuo; Melnitchouk, Wally; Kuhn, Sebastian E.; Ethier, Jacob J.; Accardi, Alberto
2016-04-05
We present a comprehensive new global QCD analysis of polarized inclusive deep-inelastic scattering, including the latest high-precision data on longitudinal and transverse polarization asymmetries from Jefferson Lab and elsewhere. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to a reduction in the PDF errors for the valence and sea quarks, as well as in the gluon polarization uncertainty at x ≳ 0.1. Furthermore, the study also provides the first determination of the flavor-separated twist-3 PDFs and the d_{2} moment of the nucleon within a global PDF analysis.
Global NLO Analysis of Nuclear Parton Distribution Functions
Hirai, M.; Kumano, S.; Nagai, T.-H.
2008-02-21
Nuclear parton distribution functions (NPDFs) are determined by a global analysis of experimental measurements on structure-function ratios F{sub 2}{sup A}/F{sub 2}{sup A{sup '}} and Drell-Yan cross section ratios {sigma}{sub DY}{sup A}/{sigma}{sub DY}{sup A{sup '}}, and their uncertainties are estimated by the Hessian method. The NPDFs are obtained in both leading order (LO) and next-to-leading order (NLO) of {alpha}{sub s}. As a result, valence-quark distributions are relatively well determined, whereas antiquark distributions at x>0.2 and gluon distributions in the whole x region have large uncertainties. The NLO uncertainties are slightly smaller than the LO ones; however, such a NLO improvement is not as significant as the nucleonic case.
Studies of transverse momentum dependent parton distributions and Bessel weighting
Aghasyan, M.; Avakian, H.; De Sanctis, E.; Gamberg, L.; Mirazita, M.; Musch, B.; Prokudin, A.; Rossi, P.
2015-03-01
In this paper we present a new technique for analysis of transverse momentum dependent parton distribution functions, based on the Bessel weighting formalism. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. Using a fully differential cross section for the process, the effect of four momentum conservation is analyzed using various input models for transverse momentum distributions and fragmentation functions. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Monte Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy/Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.
Studies of transverse momentum dependent parton distributions and Bessel weighting
Aghasyan, M.; Avakian, H.; De Sanctis, E.; ...
2015-03-01
In this paper we present a new technique for analysis of transverse momentum dependent parton distribution functions, based on the Bessel weighting formalism. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. Using a fully differential cross section for the process, the effect of four momentum conservation is analyzed using various input models for transverse momentum distributions and fragmentation functions. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Montemore » Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy/Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.« less
Proton structure and parton distribution functions from HERA
NASA Astrophysics Data System (ADS)
Chekelian, Vladimir
2016-11-01
The H1 and ZEUS collaborations at the electron-proton collider HERA collected e± p scattering data corresponding to an integrated luminosity of about 1 fb-1. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV, with different electric charges and longitudinal polarisation of the electron beam. Using these data inclusive neutral and charged current deep inelastic cross sections were measured over six orders of magnitude in negative four-momentum-transfer squared, Q2, and Bjorken x. A combination of all inclusive cross sections, published by the H1 and ZEUS collaborations at HERA, was performed. Using these combined HERA data and the individual H1 and ZEUS data taken using the polarised electron beams, the proton structure functions F2, FγZ2, xFγZ3 and FL were obtained, and scaling violations, electroweak unification, and polarisation effects in the charged current process were demonstrated. The combined cross sections were used as a sole input to QCD analyses at leading, next-to-leading and next-to-next-to-leading orders, providing a new set of parton distribution functions, denoted as HERAPDF2.0. An extension of the analysis by including HERA data on charm and jet production allowed a simultaneous determination of parton distributions and the strong coupling.
Transverse momentum-dependent parton distribution functions in lattice QCD
Engelhardt, Michael G.; Musch, Bernhard U.; Haegler, Philipp G.; Negele, John W.; Schaefer, Andreas
2013-08-01
A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.
DESHPANDE,A.; VOGELSANG, W.
2007-10-08
The determination of the polarized gluon distribution is a central goal of the RHIC spin program. Recent achievements in polarization and luminosity of the proton beams in RHIC, has enabled the RHIC experiments to acquire substantial amounts of high quality data with polarized proton beams at 200 and 62.4 GeV center of mass energy, allowing a first glimpse of the polarized gluon distribution at RHIC. Short test operation at 500 GeV center of mass energy has also been successful, indicating absence of any fundamental roadblocks for measurements of polarized quark and anti-quark distributions planned at that energy in a couple of years. With this background, it has now become high time to consider how all these data sets may be employed most effectively to determine the polarized parton distributions in the nucleon, in general, and the polarized gluon distribution, in particular. A global analysis of the polarized DIS data from the past and present fixed target experiments jointly with the present and anticipated RHIC Spin data is needed.
Transverse momentum-dependent parton distribution functions from lattice QCD
Michael Engelhardt, Philipp Haegler, Bernhard Musch, John Negele, Andreas Schaefer
2012-12-01
Transverse momentum-dependent parton distributions (TMDs) relevant for semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process can be defined in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection. Starting from such a definition, a scheme to determine TMDs in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are obtained using ensembles at the pion masses 369MeV and 518MeV, focusing in particular on the dependence of these shifts on the staple extent and a Collins-Soper-type evolution parameter quantifying proximity of the staples to the light cone.
From Bethe-Salpeter Wave functions to Generalised Parton Distributions
NASA Astrophysics Data System (ADS)
Mezrag, C.; Moutarde, H.; Rodríguez-Quintero, J.
2016-09-01
We review recent works on the modelling of generalised parton distributions within the Dyson-Schwinger formalism. We highlight how covariant computations, using the impulse approximation, allows one to fulfil most of the theoretical constraints of the GPDs. Specific attention is brought to chiral properties and especially the so-called soft pion theorem, and its link with the Axial-Vector Ward-Takahashi identity. The limitation of the impulse approximation are also explained. Beyond impulse approximation computations are reviewed in the forward case. Finally, we stress the advantages of the overlap of lightcone wave functions, and possible ways to construct covariant GPD models within this framework, in a two-body approximation.
Frederico, T.; Pace, E.; Pasquini, B.; Salme, G.
2010-08-05
Longitudinal and transverse parton distributions for pion and nucleon are calculated from hadron vertexes obtained by a study of form factors within relativistic quark models. The relevance of the one-gluon-exchange dominance at short range for the behavior of the form factors at large momentum transfer and of the parton distributions at the end points is stressed.
Towards a model of pion generalized parton distributions from Dyson-Schwinger equations
Moutarde, H.
2015-04-10
We compute the pion quark Generalized Parton Distribution H{sup q} and Double Distributions F{sup q} and G{sup q} in a coupled Bethe-Salpeter and Dyson-Schwinger approach. We use simple algebraic expressions inspired by the numerical resolution of Dyson-Schwinger and Bethe-Salpeter equations. We explicitly check the support and polynomiality properties, and the behavior under charge conjugation or time invariance of our model. We derive analytic expressions for the pion Double Distributions and Generalized Parton Distribution at vanishing pion momentum transfer at a low scale. Our model compares very well to experimental pion form factor or parton distribution function data.
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sections $\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$ for the $ep\\to e^\\prime p^\\prime \\gamma$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sectionsmore » $$\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$$ for the $$ep\\to e^\\prime p^\\prime \\gamma$$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($$Q^2,x_B,t$$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.« less
Jo, H S; Girod, F X; Avakian, H; Burkert, V D; Garçon, M; Guidal, M; Kubarovsky, V; Niccolai, S; Stoler, P; Adhikari, K P; Adikaram, D; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Compton, N; Contalbrigo, M; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dupre, R; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Harrison, N; Hattawy, M; Hicks, K; Hirlinger Saylor, N; Ho, D; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Joo, K; Joosten, S; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Kuhn, S E; Kuleshov, S V; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; McKinnon, B; Meziani, Z E; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Movsisyan, A; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Net, L A; Niculescu, G; Osipenko, M; Ostrovidov, A I; Paolone, M; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Puckett, A J R; Raue, B A; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Simonyan, A; Skorodumina, Iu; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S; Strakovsky, I I; Strauch, S; Sytnik, V; Tian, Ye; Tkachenko, S; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I
2015-11-20
Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}.
NASA Astrophysics Data System (ADS)
Jo, H. S.; Girod, F. X.; Avakian, H.; Burkert, V. D.; Garçon, M.; Guidal, M.; Kubarovsky, V.; Niccolai, S.; Stoler, P.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Elouadrhiri, L.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Hattawy, M.; Hicks, K.; Hirlinger Saylor, N.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; McKinnon, B.; Meziani, Z. E.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Park, K.; Pasyuk, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Simonyan, A.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration
2015-11-01
Unpolarized and beam-polarized fourfold cross sections (d4σ /d Q2d xBd t d ϕ ) for the e p →e'p'γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q2,xB,t ) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H , expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction xB.
Dual parametrization of generalized parton distributions in two equivalent representations
NASA Astrophysics Data System (ADS)
Müller, D.; Polyakov, M. V.; Semenov-Tian-Shansky, K. M.
2015-03-01
The dual parametrization and the Mellin-Barnes integral approach represent two frameworks for handling the double partial wave expansion of generalized parton distributions (GPDs) in the conformal partial waves and in the t-channel SO(3) partial waves. Within the dual parametrization framework, GPDs are represented as integral convolutions of forward-like functions whose Mellin moments generate the conformal moments of GPDs. The Mellin-Barnes integral approach is based on the analytic continuation of the GPD conformal moments to the complex values of the conformal spin. GPDs are then represented as the Mellin-Barnes-type integrals in the complex conformal spin plane. In this paper we explicitly show the equivalence of these two independently developed GPD representations. Furthermore, we clarify the notions of the J = 0 fixed pole and the D-form factor. We also provide some insight into GPD modeling and map the phenomenologically successful Kumerički-Müller GPD model to the dual parametrization framework by presenting the set of the corresponding forward-like functions. We also build up the reparametrization procedure allowing to recast the double distribution representation of GPDs in the Mellin-Barnes integral framework and present the explicit formula for mapping double distributions into the space of double partial wave amplitudes with complex conformal spin.
The ABM parton distributions tuned to LHC data
NASA Astrophysics Data System (ADS)
Alekhin, S.; Blümlein, J.; Moch, S.
2014-03-01
We present a global fit of parton distributions at next-to-next-to-leading order (NNLO) in QCD. The fit is based on the world data for deep-inelastic scattering, fixed-target data for the Drell-Yan process and includes, for the first time, data from the Large Hadron Collider (LHC) for the Drell-Yan process and the hadroproduction of top-quark pairs. The analysis applies the fixed-flavor number scheme for nf=3, 4, 5, uses the MS¯ scheme for the strong coupling αs and the heavy-quark masses and keeps full account of the correlations among all nonperturbative parameters. At NNLO this returns the values of αs(MZ)=0.1132±0.0011 and mt(pole)=171.2±2.4 GeV for the top-quark pole mass. The fit results are used to compute benchmark cross sections for the Higgs production at the LHC to NNLO accuracy. We compare our results to those obtained by other groups and show that differences can be linked to different theoretical descriptions of the underlying physical processes.
Q2-DEPENDENCE of the Statistical Parton Distributions in the Valon Approach
NASA Astrophysics Data System (ADS)
Sohaily, S.; Yazdanpanah, M. M.; Mirjalili, A.
2012-06-01
We employ the statistical approach to obtain the nucleon parton distributions. Statistical distributions are considered as well for partons in the valon model in which a nucleon is assumed to be a state of three valence quark clusters (valon). Analytic expressions of the x-dependent of parton distribution functions (PDFs) in the valon model are obtained statistically in the whole x region [0, 1] in terms of the statistical parameters such as temperature, chemical potential and accessible volume. Since PDFs are obtained by taking the required sum rules including Gottfried sum rule at different energy scales, the Q2-dependence of these parameters can be obtained. Therefore the parton distributions as a function of Q2 will be resulted. To make the calculations more precise, we extend our results to contain three flavors rather than two light u and d quarks.
Working Group I: Parton distributions: Summary report for the HERA LHC Workshop Proceedings
Dittmar, M.; Forte, S.; Glazov, A.; Moch, S.; Alekhin, S.; Altarelli, G.; Andersen, Jeppe R.; Ball, R.D.; Blumlein, J.; Bottcher, H.; Carli, T.; Ciafaloni, M.; Colferai, D.; Cooper-Sarkar, A.; Corcella, G.; Del Debbio, L.; Dissertori, G.; Feltesse, J.; Guffanti, A.; Gwenlan, C.; Huston, J.; /Zurich, ETH /DESY, Zeuthen /Serpukhov, IHEP /CERN /Rome III U. /INFN, Rome3 /Cambridge U. /Edinburgh U. /Florence U. /INFN, Florence /Oxford U. /DSM, DAPNIA, Saclay /Michigan State U. /Uppsala U. /Barcelona U., ECM /Podgorica U. /Turin U. /INFN, Turin /Harish-Chandra Res. Inst. /Fermilab /Hamburg U., Inst. Theor. Phys. II
2005-11-01
We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in particular from current and forthcoming HERA experiments. We give an overview of reference LHC processes and their associated PDF uncertainties, and study in detail W and Z production at the LHC.We discuss the precision which may be obtained from the analysis of existing HERA data, tests of consistency of HERA data from different experiments, and the combination of these data. We determine further improvements on PDFs which may be obtained from future HERA data (including measurements of F{sub L}), and from combining present and future HERA data with present and future hadron collider data. We review the current status of knowledge of higher (NNLO) QCD corrections to perturbative evolution and deep-inelastic scattering, and provide reference results for their impact on parton evolution, and we briefly examine non-perturbative models for parton distributions. We discuss the state-of-the art in global parton fits, we assess the impact on them of various kinds of data and of theoretical corrections, by providing benchmarks of Alekhin and MRST parton distributions and a CTEQ analysis of parton fit stability, and we briefly presents proposals for alternative approaches to parton fitting. We summarize the status of large and small x resummation, by providing estimates of the impact of large x resummation on parton fits, and a comparison of different approaches to small x resummation, for which we also discuss numerical techniques.
NASA Astrophysics Data System (ADS)
Kwieciński, Jan; Maul, Martin
2003-02-01
In this paper we derive an integral equation for the evolution of unintegrated (longitudinally) polarized quark and gluon parton distributions. The conventional Catani-Ciafaloni-Fiorani-Marchesini (CCFM) framework is modified at small x in order to incorporate the QCD expectations concerning the double ln2(1/x) resummation at low x for the integrated distributions. Complete Altarelli-Parisi splitting functions are included that makes the formalism compatible with the leading order Altarelli-Parisi evolution at large and moderately small values of x. The obtained modified polarized CCFM equation is shown to be partially diagonalized by the Fourier-Bessel transformation. Results of the numerical solution for this modifed polarized CCFM equation for the nonsinglet quark distributions are presented.
NASA Astrophysics Data System (ADS)
Hino, S.; Kumano, S.
1999-09-01
We analyze the polarized Drell-Yan processes with spin-1/2 and spin-1 hadrons in a parton model. Quark and antiquark correlation functions are expressed in terms of possible combinations of Lorentz vectors and pseudovectors with the constrains of Hermiticity, parity conservation, and time-reversal invariance. Then, we find tensor-polarized distributions for a spin-1 hadron. The naive parton model predicts that there exist 19 structure functions. However, there are only four or five nonvanishing structure functions, depending on whether the cross section is integrated over the virtual-photon transverse momentum Q-->T or the limit QT-->0 is taken. One of the finite structure functions is related to the tensor-polarized distribution b1, and it does not exist in the proton-proton reactions. The vanishing structure functions should be associated with higher-twist physics. The tensor distributions can be measured by the quadrupole polarization measurements. The Drell-Yan process has an advantage over the lepton reaction in the sense that the antiquark tensor polarization could be extracted rather easily.
nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties
Kusina, A.; Jezo, T.; Clark, D. B.; Keppel, Cynthia; Lyonnet, F.; Morfin, Jorge; Olness, F. I.; Owens, Jeff; Schienbein, I.
2015-09-01
We present the first official release of the nCTEQ nuclear parton distribution functions with errors. The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important addition is the inclusion of pion production data from RHIC that give us a handle on constraining the gluon PDF. This contribution summarizes our results from arXiv:1509.00792 and concentrates on the comparison with other groups providing nuclear parton distributions.
Heavy quarkonium production at collider energies: Partonic cross section and polarization
Qiu, Jian -Wei; Kang, Zhong -Bo; Ma, Yan -Qing; Sterman, George
2015-01-27
We calculate the O(α³_{s}) short-distance, QCD collinear-factorized coefficient functions for all partonic channels that include the production of a heavy quark pair at short distances. Thus, this provides the first power correction to the collinear-factorized inclusive hadronic production of heavy quarkonia at large transverse momentum, _{pT}, including the full leading-order perturbative contributions to the production of heavy quark pairs in all color and spin states employed in NRQCD treatments of this process. We discuss the role of the first power correction in the production rates and the polarizations of heavy quarkonia in high-energy hadronic collisions. The consistency of QCD collinear factorization and nonrelativistic QCD factorization applied to heavy quarkonium production is also discussed.
Heavy quarkonium production at collider energies: Partonic cross section and polarization
Qiu, Jian -Wei; Kang, Zhong -Bo; Ma, Yan -Qing; ...
2015-01-27
We calculate the O(α³s) short-distance, QCD collinear-factorized coefficient functions for all partonic channels that include the production of a heavy quark pair at short distances. Thus, this provides the first power correction to the collinear-factorized inclusive hadronic production of heavy quarkonia at large transverse momentum, pT, including the full leading-order perturbative contributions to the production of heavy quark pairs in all color and spin states employed in NRQCD treatments of this process. We discuss the role of the first power correction in the production rates and the polarizations of heavy quarkonia in high-energy hadronic collisions. The consistency of QCD collinearmore » factorization and nonrelativistic QCD factorization applied to heavy quarkonium production is also discussed.« less
Transverse-momentum-dependent parton distributions in a spectator diquark model
F Conti, A Bacchetta, M Radici
2009-09-01
Within the framework of a spectator diquark model of the nucleon, involving both scalar and axial-vector diquarks, we calculate all the leading-twist transverse-momentum-dependent parton distribution functions (TMDs). Naive Time-odd densities are generated through a one-gluon-loop rescattering mechanism, simulating the final state interactions required for these functions to exist. Analytic results are obtained for all the TMDs, and a connection with the light-cone wave functions formalism is also established. The model parameters are fixed by reproducing the phenomenological parametrizations of unpolarized and helicity parton distributions at the lowest available scale. Predictions for the other parton densities are given and, whenever possible, compared with available parametrizations.
Generalized Parton Distributions and Deep Exclusive Reactions: Present Program at Jlab
Michel Garcon
2004-07-01
We review briefly the physical concept of generalized parton distributions and the experimental challenges associated with the corresponding measurements of deep exclusive reactions. The first data obtained at Jefferson Lab for exclusive photon (DVCS) and vector meson (DVMP) electroproduction above the resonance-excitation region are described. Two upcoming dedicated DVCS experiments are presented in some detail.
Correlations in double parton distributions: perturbative and non-perturbative effects
NASA Astrophysics Data System (ADS)
Rinaldi, Matteo; Scopetta, Sergio; Traini, Marco; Vento, Vicente
2016-10-01
The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincaré covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 %. We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally.
New parton distributions from large-x and low-Q^{2} data
Alberto Accardi; Christy, M. Eric; Keppel, Cynthia E.; Melnitchouk, Wally; Monaghan, Peter A.; Morfin, Jorge G.; Owens, Joseph F.
2010-02-11
We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x. Effects of target mass corrections (TMCs), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. Furthermore, the behavior of the d quark as x → 1 is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models the d-quark distribution at large x is found to be softer than in previous fits performed with more restrictive cuts.
Guzey, Vadim; Goeke, Klaus; Siddikov, Marat
2009-01-01
We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact parameter dependent nuclear parton distributions (PDFs). Nuclear shadowing induces non-trivial correlations between the impact parameter $b$ and the light-cone fraction $x$. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on $^{208}$Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issue of the extraction of the DVCS signal from the $e A \\to e \\gamma A$ cross section. We find that the $e A \\to e \\gamma A$ differential cross section is dominated by DVCS at the momentum transfer $t$ near the minima of the nuclear form factor. We also find that nuclear shadowing leads
The Generalized Parton Distribution program after the Jefferson Lab 12 GeV upgrade
Franck Sabatie
2009-12-01
The Generalized Parton Distribution framework was introduced in the late 90's and describes the nucleon in a revolutionary way, correlating the information from both momentum and transverse position space into experimentally accessible functions. After a brief introduction, this article reviews the Jefferson Lab 6 GeV measurements of Deeply Virtual Compton Scattering in Halls A and B, which give a unique access to Generalized Parton Distributions (GPD). The second half of this article reviews the Jefferson Lab 12 GeV upgrade in general terms, and then focuses on the GPD program in Halls A and B. This second generation of experiments will yield more accurate, more complete data in a wider kinematical range than any experiment ever before, using the full capability of a higher beam energy, higher luminosities, upgraded detectors and refined extraction techniques.
NASA Astrophysics Data System (ADS)
Kusina, A.; Stavreva, T.; Berge, S.; Olness, F. I.; Schienbein, I.; Kovařík, K.; Ježo, T.; Yu, J. Y.; Park, K.
2012-05-01
Global analyses of parton distribution functions (PDFs) have provided incisive constraints on the up and down quark components of the proton, but constraining the other flavor degrees of freedom is more challenging. Higher-order theory predictions and new data sets have contributed to recent improvements. Despite these efforts, the strange quark parton distribution function has a sizable uncertainty, particularly in the small x region. We examine the constraints from experiment and theory, and investigate the impact of this uncertainty on LHC observables. In particular, we study W/Z production to see how the s quark uncertainty propagates to these observables, and examine the extent to which precise measurements at the LHC can provide additional information on the proton flavor structure.
Spin-dependent parton distributions in the nucleon
I.C. Cloet; W. Bentz; A.W. Thomas
2005-04-01
Spin-dependent quark light-cone momentum distributions are calculated for a nucleon in the nuclear medium. We utilize a modified NJL model where the nucleon is described as a composite quark-diquark state. Scalar and vector mean fields are incorporated in the nuclear medium and these fields couple to the confined quarks in the nucleon. The effect of these fields on the spin-dependent distributions and consequently the axial charges is investigated. Our results for the ''spin-dependent EMC effect'' are also discussed.
The Generalized Parton Distribution program in Hall A at Jefferson Lab
Camacho, C. Munoz
2008-10-13
Recent results on the Generalized Parton Distribution (GPD) program at Jefferson Lab (JLab) will be presented. The emphasis will be in the Hall A program aiming at measuring Q{sup 2}--dependences of different terms of the Deeply Virtual Compton Scattering (DVCS) cross section. This is a fundamental step before one can extract GPD information from JLab DVCS data. Neutral pion production will also be discussed and results from the CLAS collaboration will be shown. Finally, the upcoming program in Hall A, using both a 6 GeV beam ({approx_equal}2010) and a 11 GeV beam ({approx_equal}2015) will be described.
Hadron production in deuteron-gold collisions and nuclear parton distributions
Adeluyi, Adeola; Fai, George
2007-11-15
We calculate nuclear modification factors R{sub dAu}, central-to-peripheral ratios, R{sub CP}, and pseudorapidity asymmetries Y{sub Asym} in deuteron-gold collisions at {radical}(s)=200 GeV in the framework of leading-order (LO) perturbative quantum chromodynamics. We use the Eskola-Kolhinen-Salgado (EKS), the Frankfurt-Guzey-Strikman (FGS), and the Hirai-Kumano-Nagai (HKN) nuclear parton distribution functions and the Albino-Kramer-Kniehl (AKK) fragmentation functions in our calculations. Results are compared to experimental data from the BRAHMS and STAR collaborations.
Hadron production in deuteron-gold collisions and nuclear parton distributions
NASA Astrophysics Data System (ADS)
Adeluyi, Adeola; Fai, George
2007-11-01
We calculate nuclear modification factors RdAu, central-to-peripheral ratios, RCP, and pseudorapidity asymmetries YAsym in deuteron-gold collisions at s=200 GeV in the framework of leading-order (LO) perturbative quantum chromodynamics. We use the Eskola-Kolhinen-Salgado (EKS), the Frankfurt-Guzey-Strikman (FGS), and the Hirai-Kumano-Nagai (HKN) nuclear parton distribution functions and the Albino-Kramer-Kniehl (AKK) fragmentation functions in our calculations. Results are compared to experimental data from the BRAHMS and STAR collaborations.
APFEL Web: a web-based application for the graphical visualization of parton distribution functions
NASA Astrophysics Data System (ADS)
Carrazza, Stefano; Ferrara, Alfio; Palazzo, Daniele; Rojo, Juan
2015-05-01
We present APFEL Web, a Web-based application designed to provide a flexible user-friendly tool for the graphical visualization of parton distribution functions. In this note we describe the technical design of the APFEL Web application, motivating the choices and the framework used for the development of this project. We document the basic usage of APFEL Web and show how it can be used to provide useful input for a variety of collider phenomenological studies. Finally we provide some examples showing the output generated by the application.
The asymptotic behaviour of parton distributions at small and large x.
Ball, Richard D; Nocera, Emanuele R; Rojo, Juan
2016-01-01
It has been argued from the earliest days of quantum chromodynamics that at asymptotically small values of x the parton distribution functions (PDFs) of the proton behave as [Formula: see text], where the values of [Formula: see text] can be deduced from Regge theory, while at asymptotically large values of x the PDFs behave as [Formula: see text], where the values of [Formula: see text] can be deduced from the Brodsky-Farrar quark counting rules. We critically examine these claims by extracting the exponents [Formula: see text] and [Formula: see text] from various global fits of parton distributions, analysing their scale dependence, and comparing their values to the naive expectations. We find that for valence distributions both Regge theory and counting rules are confirmed, at least within uncertainties, while for sea quarks and gluons the results are less conclusive. We also compare results from various PDF fits for the structure function ratio [Formula: see text] at large x, and caution against unrealistic uncertainty estimates due to overconstrained parametrisations.
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
Frankfurt, L.; Hyde, C. E.; Strikman, M.; Weiss, C.
2007-03-01
We study rapidity gap survival (RGS) in the production of high-mass systems (H=dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp{yields}p+(gap)+H+(gap)+p. Our approach is based on the idea that hard and soft interactions are approximately independent because they proceed over widely different time and distance scales. We implement this idea in a partonic description of proton structure, which allows for a model-independent treatment of the interplay of hard and soft interactions. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons, whose amplitude is calculable in terms of the gluon generalized parton distribution (GPD), measured in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate neglecting correlations between hard and soft interactions (independent interaction approximation). We obtain an analytic expression for the RGS probability in terms of the phenomenological pp elastic scattering amplitude, without reference to the eikonal approximation. Contributions from inelastic intermediate states are suppressed. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons ('diffraction pattern'). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the
New parton distribution functions from a global analysis of quantum chromodynamics
NASA Astrophysics Data System (ADS)
Dulat, Sayipjamal; Hou, Tie-Jiun; Gao, Jun; Guzzi, Marco; Huston, Joey; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C.-P.
2016-02-01
We present new parton distribution functions (PDFs) at next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged-lepton rapidity asymmetry data, as well as the use of a more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. For completeness, we also present the CT14 PDFs determined at the LO and the NLO in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number schemes, to deal with heavy partons, with up to three, four, and six active flavors.
New parton distribution functions from a global analysis of quantum chromodynamics
Dulat, Sayipjamal; Hou, Tie -Jiun; Gao, Jun; ...
2016-02-16
Here, we present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. Formore » completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.« less
New parton distribution functions from a global analysis of quantum chromodynamics
Dulat, Sayipjamal; Hou, Tie -Jiun; Gao, Jun; Guzzi, Marco; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C. -P.; Huston, Joey
2016-02-16
Here, we present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. For completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various α_{s} values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.
Parton distribution in pseudoscalar mesons with a light-front constituent quark model
NASA Astrophysics Data System (ADS)
de Melo, J. P. B. C.; Ahmed, Isthiaq; Tsushima, Kazuo
2016-05-01
We compute the distribution amplitudes of the pion and kaon in the light-front constituent quark model with the symmetric quark-bound state vertex function [1, 2, 3]. In the calculation we explicitly include the flavor-SU(3) symmetry breaking effect in terms of the constituent quark masses of the up (down) and strange quarks. To calculate the kaon parton distribution functions (PDFs), we use both the conditions in the light-cone wave function, i.e., when s ¯ quark is on-shell, and when u quark is on-shell, and make a comparison between them. The kaon PDFs calculated in the two different conditions clearly show asymmetric behaviour due to the flavor SU(3)-symmetry breaking implemented by the quark masses [4, 5].
Huston, Joey [Co-Spokesperson; Ownes, Joseph [Co-Spokesperson
The Coordinated Theoretical-Experimental Project on QCD is a multi-institutional collaboration devoted to a broad program of research projects and cooperative enterprises in high-energy physics centered on Quantum Chromodynamics (QCD) and its implications in all areas of the Standard Model and beyond. The Collaboration consists of theorists and experimentalists at 18 universities and 5 national laboratories. More than 65 sets of Parton Distribution Functions are available for public access. Links to many online software tools, information about Parton Distribution Functions, papers, and other resources are also available.
New limits on intrinsic charm in the nucleon from global analysis of parton distributions
Jimenez-Delgado, P.; Hobbs, T. J.; Londergan, J. T.; ...
2015-02-27
We present a new global QCD analysis of parton distribution functions, allowing for possible intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high-energy scattering data for Q2 ≥ 1 GeV2 and W2 ≥ 3.5 GeV2, including fixed-target proton and deuteron deep cross sections at lower energies that were excluded in previously global analyses. The expanded data set places more stringent constraints on the momentum carried by IC, with (x)IC at most 0.5% (corresponding to an IC normalization of ~1%) at the 4σ level for ΔX2 = 1.more » We also assess the impact of older EMC measurements of Fc2c at large x, which favor a nonzero IC, but with very large X2 values.« less
NASA Astrophysics Data System (ADS)
Bedlinskiy, I.; Kubarovsky, V.; Stoler, P.; Adhikari, K. P.; Akbar, Z.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Elouadrhiri, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Fersch, R.; Filippi, A.; Fleming, J. A.; Forest, T. A.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gleason, C.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khachatryan, M.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kuhn, S. E.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; MacGregor, I. J. D.; Markov, N.; McKinnon, B.; Meziani, Z. E.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schumacher, R. A.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tian, Ye; Torayev, B.; Turisini, M.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Yurov, M.; Zachariou, N.; Zhang, J.; Zonta, I.; CLAS Collaboration
2017-03-01
The cross section of the exclusive η electroproduction reaction e p →e'p'η was measured at Jefferson Laboratory with a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d4σ /d t d Q2d xBd ϕη and structure functions σU=σT+ɛ σL,σT T , and σL T, as functions of t , were obtained over a wide range of Q2 and xB. The η structure functions are compared with those previously measured for π0 at the same kinematics. At low t , both π0 and η are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. The π0 and η data, when taken together, can facilitate the flavor decomposition of the transversity GPDs.
nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties in the CTEQ framework
Kovarik, K.; Kusina, A.; Clark, D. B.; Keppel, C.; Lyonnet, F.; Morfin, J. G.; Olness, F. I.; Owens, J. F.; Schienbein, I.
2016-04-28
We present the new nCTEQ15 set of nuclear parton distribution functions with uncertainties. This fit extends the CTEQ proton PDFs to include the nuclear dependence using data on nuclei all the way up to ^{208}Pb. The uncertainties are determined using the Hessian method with an optimal rescaling of the eigenvectors to accurately represent the uncertainties for the chosen tolerance criteria. In addition to the Deep Inelastic Scattering (DIS) and Drell-Yan (DY) processes, we also include inclusive pion production data from RHIC to help constrain the nuclear gluon PDF. Here, we investigate the correlation of the data sets with specific nPDF flavor components, and asses the impact of individual experiments. We also provide comparisons of the nCTEQ15 set with recent fits from other groups.
Exclusive η electroproduction at W>2 GeV with CLAS and transversity generalized parton distributions
Bedlinskiy, I.; Kubarovsky, V.; Stoler, P.; ...
2017-03-10
The cross section of the exclusive η electroproduction reaction ep → e'p'η was measured at Jefferson Laboratory with a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d4σ/dtdQ2dxBdΦη and structure functions σU = σT + εσL, σTT, and σLT, as functions of t, were obtained over a wide range of Q2 and xB. The η structure functions are compared with those previously measured for π0 at the same kinematics. At low t, both π0 and η are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. As a result, the π0more » and η data, when taken together, can facilitate the flavor decomposition of the transversity GPDs.« less
Agreement of neutrino deep inelastic scattering data with global fits of parton distributions.
Paukkunen, Hannu; Salgado, Carlos A
2013-05-24
The compatibility of neutrino-nucleus deep inelastic scattering data within the universal, factorizable nuclear parton distribution functions has been studied independently by several groups in the past few years. The conclusions are contradictory, ranging from a violation of the universality up to a good agreement, most of the controversy originating from the use of the neutrino-nucleus data from the NuTeV Collaboration. Here, we pay attention to non-negligible differences in the absolute normalization between different neutrino data sets. We find that such variations are large enough to prevent a tensionless fit to all data simultaneously and could therefore misleadingly point towards nonuniversal nuclear effects. We propose a concrete method to deal with the absolute normalization and show that an agreement between independent neutrino data sets is established.
nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties in the CTEQ framework
Kovarik, K.; Kusina, A.; Jezo, T.; ...
2016-04-28
We present the new nCTEQ15 set of nuclear parton distribution functions with uncertainties. This fit extends the CTEQ proton PDFs to include the nuclear dependence using data on nuclei all the way up to 208Pb. The uncertainties are determined using the Hessian method with an optimal rescaling of the eigenvectors to accurately represent the uncertainties for the chosen tolerance criteria. In addition to the Deep Inelastic Scattering (DIS) and Drell-Yan (DY) processes, we also include inclusive pion production data from RHIC to help constrain the nuclear gluon PDF. Here, we investigate the correlation of the data sets with specific nPDFmore » flavor components, and asses the impact of individual experiments. We also provide comparisons of the nCTEQ15 set with recent fits from other groups.« less
How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function
NASA Astrophysics Data System (ADS)
Manohar, Aneesh; Nason, Paolo; Salam, Gavin P.; Zanderighi, Giulia
2016-12-01
It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (e p ) scattering data, in effect viewing the e p →e +X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex. We write its cross section in two ways: one in terms of proton structure functions, the other in terms of a photon distribution. Requiring their equivalence yields the photon distribution as an integral over proton structure functions. As a result of the good precision of e p data, we constrain the photon PDF at the level of 1%-2% over a wide range of momentum fractions.
Moments of Nucleon's Parton Distribution for the Sea and Valence Quarks from Lattice QCD
Deka, Mridupawan; Streuer, Thomas; Doi, Takumi; Dong, Shao-Jing; Draper, Terrence; Liu, Keh-Fei; Mathur, Nilmani; Thomas, Anthony
2009-01-01
We extend the study of lowest moments, $
A new phenomenological investigation of KMR and MRW unintegrated parton distribution functions
NASA Astrophysics Data System (ADS)
Modarres, M.; Hosseinkhani, H.; Olanj, N.; Masouminia, M. R.
2015-11-01
We address the longitudinal proton structure function, F_L(x,Q^2), from the k_t-factorization formalism by using the unintegrated parton distribution functions (UPDF) which are generated through the KMR and MRW procedures. The LO UPDF of the KMR prescription is extracted, by taking into account the PDF of Martin et al, i.e., MSTW2008-LO and MRST99-NLO, and next the NLO UPDF of the MRW scheme is generated through the set of MSTW2008-NLO PDF as the input. The different aspects of F_L(x,Q^2) in the two approaches, as well as its perturbative and non-perturbative parts, are calculated. Then the comparison of F_L(x,Q^2) is made with the data given by the ZEUS and H1 collaborations. It is demonstrated that the extracted F_L(x,Q^2), based on the UPDF of two schemes, are consistent with the experimental data, and to a good approximation they are independent of the input PDF. But the one developed from the KMR prescription has better agreement with the data with respect to that of MRW. As has been suggested, by lowering the factorization scale or the Bjorken variable in the related experiments it may be possible to analyze the present theoretical approaches more accurately.
CTEQ-TEA parton distribution functions and HERA Run I and II combined data
NASA Astrophysics Data System (ADS)
Hou, Tie-Jiun; Dulat, Sayipjamal; Gao, Jun; Guzzi, Marco; Huston, Joey; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C.-P.
2017-02-01
We analyze the impact of the recent HERA Run I +II combination of inclusive deep inelastic scattering cross-section data on the CT14 global analysis of parton distribution functions (PDFs). New PDFs at next-to-leading order and next-to-next-to-leading order, called CT14 HERA 2 , are obtained by a refit of the CT14 data ensembles, in which the HERA Run I combined measurements are replaced by the new HERA Run I +II combination. The CT14 functional parametrization of PDFs is flexible enough to allow good descriptions of different flavor combinations, so we use the same parametrization for CT14 HERA 2 but with an additional shape parameter for describing the strange quark PDF. We find that the HERA I +II data can be fit reasonably well, and both CT14 and CT14 HERA 2 PDFs can describe equally well the non-HERA data included in our global analysis. Because the CT14 and CT14 HERA 2 PDFs agree well within the PDF errors, we continue to recommend CT14 PDFs for the analysis of LHC Run 2 experiments.
Parameterization of Parton Distributions Functions Based on Self-Organizing Maps
NASA Astrophysics Data System (ADS)
Loitiere, Y.; Honkanen, H.; Liuti, S.
2006-11-01
Neural network algorithms have been recently applied to construct Parton Distribution Functions (PDFs) parametrizations which provide an alternative to standard global fitting procedures [1]. In this contribution we propose a different technique, namely an interactive neural network algorithm using Self-Organizing Maps (SOMs) [2]. SOMs generate a nonuniform projection from a high dimensional data space onto a low dimensional one (usually 1 or 2 dimensions) by clustering similar PDF representations together. Our SOMs are trained on progressively narrower selections of data samples. The selection criterion is that of convergence towards a neighborhood of the experimental data. Our procedure utilizes all available data on deep inelastic scattering in the kinematical region of 0.001 <=x <= 0.75, and 1 <=Q^2 <= 100 GeV^2, with a cut on the final state invariant mass, W^2 >= 10 GeV^2. Our main goal is to provide a fitting procedure that, at variance with standard neural network approaches, allows for an increased control of the systematic bias. SOMs, in fact, enable the user to directly control the data selection procedure at various stages of the process. [1] L. Del Debbio, S. Forte, J. I. Latorre, A. Piccione and J. Rojo, [NNPDF Collaboration], JHEP 0503, 080 (2005). [2] T. Kohonen, ``Self Organizing Maps,'' Springer-Verlag, 1997.
Zenaiev, O.; Geiser, A.; Lipka, K.; ...
2015-08-01
The impact of recent measurements of heavy-flavour production in deep inelastic ep scattering and in pp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions x of the proton momentum, down to x~5×10-6. This kinematic range is currently not covered by othermore » experimental data in perturbative QCD fits.« less
Zenaiev, O.; Geiser, A.; Lipka, K.; Blumlein, J.; Cooper-Sarkar, A.; Garzelli, M. -V.; Guzzi, M.; Kuprash, O.; Moch, S. -O.; Nadolsky, P.; Placakyte, R.; Rabbertz, K.; Schienbein, I.; Starovoitov, P.
2015-08-01
The impact of recent measurements of heavy-flavour production in deep inelastic ep scattering and in pp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions x of the proton momentum, down to x~5×10^{-6}. This kinematic range is currently not covered by other experimental data in perturbative QCD fits.
Transverse parton distribution functions at next-to-next-to-leading order: the quark-to-quark case.
Gehrmann, Thomas; Lübbert, Thomas; Yang, Li Lin
2012-12-14
We present a calculation of the perturbative quark-to-quark transverse parton distribution function at next-to-next-to-leading order based on a gauge invariant operator definition. We demonstrate for the first time that such a definition works beyond the first nontrivial order. We extract from our calculation the coefficient functions relevant for a next-to-next-to-next-to-leading logarithmic Q(T) resummation in a large class of processes at hadron colliders.
Accardi, A.; Brady, L. T.; Melnitchouk, W.; ...
2016-06-20
A new set of leading twist parton distribution functions, referred to as "CJ15", is presented, which take advantage of developments in the theoretical treatment of nuclear corrections as well as new data. The analysis includes for the first time data on the free neutron structure function from Jefferson Lab, and new high-precision charged lepton and W-boson asymmetry data from Fermilab, which significantly reduce the uncertainty on the d/u ratio at large values of x.
Jimenez-Delgado, Pedro; Hobbs, Timothy J.; Londergan, J. T.; Melnitchouk, Wally
2016-01-05
We reply to the Comment of Brodsky and Gardner on our paper "New limits on intrinsic charm in the nucleon from global analysis of parton distributions" [Phys. Rev. Lett. 114, 082002 (2015)]. We address a number of incorrect claims made about our fitting methodology, and elaborate how global QCD analysis of all available high-energy data provides no evidence for a large intrinsic charm component of the nucleon.
CT14QED parton distribution functions from isolated photon production in deep inelastic scattering
NASA Astrophysics Data System (ADS)
Schmidt, Carl; Pumplin, Jon; Stump, Daniel; Yuan, C.-P.
2016-06-01
We describe the implementation of quantum electrodynamic (QED) evolution at leading order (LO) along with quantum chromodynamic (QCD) evolution at next-to-leading order (NLO) in the CTEQ-TEA global analysis package. The inelastic contribution to the photon parton distribution function (PDF) is described by a two-parameter ansatz, coming from radiation off the valence quarks, and based on the CT14 NLO PDFs. Setting the two parameters to be equal allows us to completely specify the inelastic photon PDF in terms of the inelastic momentum fraction carried by the photon, p0γ, at the initial scale Q0=1.295 GeV . We obtain constraints on the photon PDF by comparing with ZEUS data [S. Chekanov et al. (ZEUS Collaboration), Phys. Lett. B 687, 16 (2010)] on the production of isolated photons in deep inelastic scattering, e p →e γ +X . For this comparison we present a new perturbative calculation of the process that consistently combines the photon-initiated contribution with the quark-initiated contribution. Comparison with the data allows us to put a constraint at the 90% confidence level of p0γ≲0.14 % for the inelastic photon PDF at the initial scale of Q0=1.295 GeV in the one-parameter radiative ansatz. The resulting inelastic CT14QED PDFs will be made available to the public. In addition, we also provide CT14QEDinc PDFs, in which the inclusive photon PDF at the scale Q0 is defined by the sum of the inelastic photon PDF and the elastic photon distribution obtained from the equivalent photon approximation.
NASA Astrophysics Data System (ADS)
Modarres, M.; Masouminia, M. R.; Hosseinkhani, H.; Olanj, N.
2016-01-01
In the spirit of performing a complete phenomenological investigation of the merits of Kimber-Martin-Ryskin (KMR) and Martin-Ryskin-Watt (MRW) unintegrated parton distribution functions (UPDF), we have computed the longitudinal structure function of the proton, FL (x ,Q2), from the so-called dipole approximation, using the LO and the NLO-UPDF, prepared in the respective frameworks. The preparation process utilizes the PDF of Martin et al., MSTW2008-LO and MSTW2008-NLO, as the inputs. Afterwards, the numerical results are undergone a series of comparisons against the exact kt-factorization and the kt-approximate results, derived from the work of Golec-Biernat and Stasto, against each other and the experimental data from ZEUS and H1 Collaborations at HERA. Interestingly, our results show a much better agreement with the exact kt-factorization, compared to the kt-approximate outcome. In addition, our results are completely consistent with those prepared from embedding the KMR and MRW UPDF directly into the kt-factorization framework. One may point out that the FL, prepared from the KMR UPDF shows a better agreement with the exact kt-factorization. This is despite the fact that the MRW formalism employs a better theoretical description of the DGLAP evolution equation and has an NLO expansion. Such unexpected consequence appears, due to the different implementation of the angular ordering constraint in the KMR approach, which automatically includes the resummation of ln (1 / x), BFKL logarithms, in the LO-DGLAP evolution equation.
NASA Astrophysics Data System (ADS)
Tuppan, Sam; Budnik, Garrett; Fox, Jordan
2014-09-01
The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. This research has been supported in part by the
Multiple parton scattering in nuclei: Parton energy loss
Wang, Xin-Nian; Guo, Xiao-feng
2001-02-17
Multiple parton scattering and induced parton energy loss are studied in deeply inelastic scattering (DIS) off nuclei. The effect of multiple scattering of a highly off-shell quark and the induced parton energy loss is expressed in terms of the modification to the quark fragmentation functions. The authors derive such modified quark fragmentation functions and their QCD evolution equations in DIS using the generalized factorization of higher twist parton distributions. They consider double-hard and hard-soft parton scattering as well as their interferences in the same framework. The final result, which depends on both the diagonal and off-diagonal twist-four parton distributions in nuclei, demonstrates clearly the Landau-Pomeranchuk-Migdal interference features and predicts a unique nuclear modification of the quark fragmentation functions.
Charge symmetry at the partonic level
Londergan, J. T.; Peng, J. C.; Thomas, A. W.
2010-07-01
This review article discusses the experimental and theoretical status of partonic charge symmetry. It is shown how the partonic content of various structure functions gets redefined when the assumption of charge symmetry is relaxed. We review various theoretical and phenomenological models for charge symmetry violation in parton distribution functions. We summarize the current experimental upper limits on charge symmetry violation in parton distributions. A series of experiments are presented, which might reveal partonic charge symmetry violation, or alternatively might lower the current upper limits on parton charge symmetry violation.
Laser-polarization-dependent photoelectron angular distributions from polar molecules.
Zhu, Xiaosong; Zhang, Qingbin; Hong, Weiyi; Lu, Peixiang; Xu, Zhizhan
2011-11-21
Photoelectron angular distributions (PADs) of oriented polar molecules in response to different polarized lasers are systematically investigated. It is found that the PADs of polar CO molecules show three distinct styles excited by linearly, elliptically and circularly polarized lasers respectively. In the case of elliptical polarization, a deep suppression is observed along the major axis and the distribution concentrates approximately along the minor axis. Additionally, it is also found that the concentrated distributions rotate clockwise as the ellipticity increases. Our investigation presents a method to manipulate the motion and angular distribution of photoelectrons by varying the polarization of the exciting pulses, and also implies the possibility to control the processes in laser-molecule interactions in future work.
Engelhardt, M.; Musch, B.; Bhattacharya, T.; ...
2014-06-23
Here, lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297 MeV, on a lattice with spacing 0.084 fm, selected TMD observables are accessed and compared to previous exploration at heavier pion masses on coarser lattices.
Engelhardt, Michael; Musch, Bernhard; Bhattacharya, Tanmoy; Gupta, Rajan; Hagler, Phillip; Negele, John; Pochinsky, Andrew; Shafer, Andreas; Syritsyn, Sergey; Yoon, Boram
2014-12-01
Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297MeV, on a lattice with spacing 0.084fm, selected TMD observables are accessed and compared to previous explorations at heavier pion masses on coarser lattices.
NASA Astrophysics Data System (ADS)
Sawada, Takahiro; Chang, Wen-Chen; Kumano, Shunzo; Peng, Jen-Chieh; Sawada, Shinya; Tanaka, Kazuhiro
2016-06-01
Generalized parton distributions (GPDs) encoding multidimensional information of hadron partonic structure appear as the building blocks in a factorized description of hard exclusive reactions. The nucleon GPDs have been accessed by deeply virtual Compton scattering and deeply virtual meson production with lepton beam. A complementary probe with hadron beam is the exclusive pion-induced Drell-Yan process. In this paper, we discuss recent theoretical advances on describing this process in terms of nucleon GPDs and pion distribution amplitudes. Furthermore, we address the feasibility of measuring the exclusive pion-induced Drell-Yan process π-p →μ+μ-n via a spectrometer at the High Momentum Beamline being constructed at J-PARC in Japan. Realization of such measurement at J-PARC will provide a new test of perturbative QCD descriptions of a novel class of hard exclusive reactions. It will also offer the possibility of experimentally accessing nucleon GPDs at large timelike virtuality.
NLO+NLL squark and gluino production cross sections with threshold-improved parton distributions.
Beenakker, Wim; Borschensky, Christoph; Krämer, Michael; Kulesza, Anna; Laenen, Eric; Marzani, Simone; Rojo, Juan
We present updated predictions for the cross sections for pair production of squarks and gluinos at the LHC Run II. First of all, we update the calculations based on NLO+NLL partonic cross sections by using the NNPDF3.0NLO global analysis. This study includes a full characterization of theoretical uncertainties from higher orders, PDFs and the strong coupling. Then we explore the implications for this calculation of the recent NNPDF3.0 PDFs with NLO+NLL threshold resummation. We find that the shift in the results induced by the threshold-improved PDFs is within the total theory uncertainty band of the calculation based on NLO PDFs. However, we also observe that the central values of the NLO+NLL cross sections are modified both in a qualitative and a quantitative way, illustrating the relevance and impact of using threshold-improved PDFs together with resummed partonic cross sections. The updated NLO+NLL cross sections based on NNPDF3.0NLO are publicly available in the NLL-fast format, and should be an important ingredient for the interpretation of the searches for supersymmetric particles at Run II.
Summing threshold logs in a parton shower
NASA Astrophysics Data System (ADS)
Nagy, Zoltán; Soper, Davison E.
2016-10-01
When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in α s that combine to affect hard scattering cross sections and need to be summed. We show how to accomplish this in a leading approximation in the context of a parton shower Monte Carlo event generator.
NASA Astrophysics Data System (ADS)
Kovalenko, V. N.
2013-10-01
The soft part of proton-proton interaction is considered within a phenomenological model that involves the formation of color strings. Under the assumption that an elementary collision is associated with the interaction of two color dipoles, the total inelastic cross section and the multiplicity of charged particles are estimated in order to fix model parameters. Particular attention is given to modeling of exclusive parton distributions with allowance for the energy-conservation law and for fixing the center of mass, which are necessary for describing correlations. An algorithm that describes the fusion of strings in the transverse plane and which takes into account their finite rapidity width is developed. The influence of string-fusion effects on long-range correlations is found within this mechanism.
Quantum Key Distribution with Blind Polarization Bases
NASA Astrophysics Data System (ADS)
Kye, Won-Ho; Kim, Chil-Min; Kim, M. S.; Park, Young-Jai
2005-07-01
We propose a new quantum key distribution scheme that uses the blind polarization basis. In our scheme the sender and the receiver share key information by exchanging qubits with arbitrary polarization angles without basis reconciliation. As only random polarizations are transmitted, our protocol is secure even when a key is embedded in a not-so-weak coherent-state pulse. We show its security against the photon-number splitting attack and the impersonation attack.
NASA Astrophysics Data System (ADS)
Lopez, Annette; ATLAS Collaboration
2017-01-01
Investigating the properties of a proton involved in a proton-proton collision at the Large Hadron Collider furthers our understanding of resulting processes from the collision. In the search for dark matter produced alongside a new heavy resonance, Z', or a W/Z boson, a process characterized by large missing transverse momentum from the undetected dark matter particles, parton distribution functions (PDFs) of protons were utilized to improve the Monte Carlo simulation of proton-proton collisions at &sqrt;s = 13 TeV with the ATLAS detector. The PDF set NNPDF30 leading order was used to generate events with applied cuts: missing transverse momentum greater than 250 GeV, pseudorapidity of | η | < 2 . 5 , and groomed jets with R = 1 . 0 . An algorithm was developed to do PDF reweighting from NNPDF30 leading order to the following PDF sets: NNPDF30 next-to-leading order, MMHT2014, HERAPDF20, CT14, and MSTW2008. Distributions of the transverse momentum, mass, azimuthal angle, rapidity, and pseudorapidity for the leading and subleading jets, as well as the missing transverse momentum, were produced with the PDF reweighting algorithm. The uncertainty associated with the choice of a particular PDF in creating these distributions was calculated.
Spin-flavor structure of chiral-odd generalized parton distributions in the large-Nc limit
Schweitzer, P.; Weiss, C.
2016-10-05
We study the spin-flavor structure of the nucleon's chiral-odd generalized parton distributions (transversity GPDs) in the large-Nc limit of QCD. In contrast to the chiral-even case, only three combinations of the four chiral-odd GPDs are nonzero in the leading order of the 1/Nc expansion: E-barT = ET+2H-tildeT, HT, and E-tildeT. The degeneracy is explained by the absence of spin-orbit interactions correlating the transverse momentum transfer with the transverse quark spin. It can also be deduced from the natural Nc scaling of the quark-nucleon helicity amplitudes associated with the GPDs. In the GPD E-barT the flavor-singlet component u+d is leading inmore » the 1/Nc expansion, while in HT and E-tildeT it is the flavor-nonsinglet components u–d. Furthermore, the large-Nc relations are consistent with the spin-flavor structure extracted from hard exclusive π0 and η electroproduction data, if it is assumed that the processes are mediated by twist-3 amplitudes involving the chiral-odd GPDs and the chiral-odd pseudoscalar meson distribution amplitudes.« less
Strongly interacting parton matter equilibration
Ozvenchuk, V.; Linnyk, O.; Bratkovskaya, E.; Gorenstein, M.; Cassing, W.
2012-07-15
We study the kinetic and chemical equilibration in 'infinite' parton matter within the Parton-Hadron-String Dynamics transport approach. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different energy densities. Particle abundances, kinetic energy distributions, and the detailed balance of the off-shell quarks and gluons in the strongly-interacting quarkgluon plasma are addressed and discussed.
Strongly interacting parton matter equilibration
NASA Astrophysics Data System (ADS)
Ozvenchuk, V.; Linnyk, O.; Bratkovskaya, E.; Gorenstein, M.; Cassing, W.
2012-07-01
We study the kinetic and chemical equilibration in "infinite" parton matter within the Parton-Hadron-String Dynamics transport approach. The "infinite" matter is simulated within a cubic box with periodic boundary conditions initialized at different energy densities. Particle abundances, kinetic energy distributions, and the detailed balance of the off-shell quarks and gluons in the strongly-interacting quarkgluon plasma are addressed and discussed.
NASA Astrophysics Data System (ADS)
Liu, Keh-Fei; Chang, Wen-Chen; Cheng, Hai-Yang; Peng, Jen-Chieh
2012-12-01
According to the path-integral formalism of the hadronic tensor, the nucleon sea contains two distinct components called the connected sea (CS) and the disconnected sea (DS). We discuss how the CS and DS are accessed in the lattice QCD calculation of the moments of the parton distributions. We show that the CS and DS components of u¯(x)+d¯(x) can be extracted by using recent data on the strangeness parton distribution, the CT10 global fit, and the lattice result of the ratio of the strange to u(d) moments in the disconnected insertion. The extracted CS and DS for u¯(x)+d¯(x) have a distinct Bjorken x dependence in qualitative agreement with expectation. The analysis also shows that the momentum fraction of u¯(x)+d¯(x) is about equally divided between the CS and DS at Q2=2.5GeV2. Implications for the future global analysis of parton distributions are presented.
Wigner Distributions of Quarks for Different Polarizations
NASA Astrophysics Data System (ADS)
More, Jai; Mukherjee, Asmita; Nair, Sreeraj
2017-03-01
We calculate quark Wigner distributions using the light-front wave functions in a dressed quark model. In this model, a proton target is replaced by a simplified spin-1/2 state, namely a quark dressed with a gluon. We calculate the Wigner distributions for different polarization configuration of quark and the target state in this model.
POLRADS: polarization radiance distribution measurement system.
Voss, Kenneth J; Souaidia, Nordine
2010-09-13
While the upwelling radiance distribution in the ocean can be highly polarized, there are few measurements of this parameter in the open ocean. To obtain the polarized in-water upwelling spectral radiance distribution data we have developed the POLRADS instrument. This instrument is based on the NuRADS radiance distribution camera systems in which linear polarizer's have been installed. By combining simultaneous images from three NuRADS instruments, three Stokes parameters (I, Q, U) for the water leaving radiance can be obtained for all upwelling angles simultaneously. This system measures the Stokes parameters Q/I and U/I with a 0.05-0.06 uncertainty and I with a 7-10% uncertainty.
Accardi, A.; Brady, L. T.; Melnitchouk, W.; Owens, J. F.; Sato, N.
2016-06-20
A new set of leading twist parton distribution functions, referred to as "CJ15", is presented, which take advantage of developments in the theoretical treatment of nuclear corrections as well as new data. The analysis includes for the first time data on the free neutron structure function from Jefferson Lab, and new high-precision charged lepton and W-boson asymmetry data from Fermilab, which significantly reduce the uncertainty on the d/u ratio at large values of x.
Y. C. Chen; A. Afanasev; S. J. Brodsky; C. E. Carlson; Marc Vanderhaeghen
2004-03-01
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer through the scattering off a parton in the proton. We relate the process on the nucleon to the generalized parton distributions which also enter in other wide angle scattering processes. We find that when taking the polarization transfer determinations of the form factors as input, adding in the 2 photon correction, does reproduce the Rosenbluth data.
Comment on "Reevaluation of the parton distribution of strange quarks in the nucleon"
NASA Astrophysics Data System (ADS)
Stolarski, M.
2015-11-01
The HERMES collaboration in Phys. Rev. D 89, 097101 (2014) extracted information about the strange quark density in the nucleon. One of the main results is an observation that the shape of the extracted density is very different from the shapes of the strange quark density from global QCD fits and also from that of the light antiquarks. In this paper systematic studies on the HERMES published multiplicity of pion and kaon data are presented. It is shown that the conclusions concerning the strange quark distribution in the nucleon reached in Phys. Rev. D 89, 097101 (2014) are at the moment premature.
NASA Astrophysics Data System (ADS)
Tatur, Stanislaw; Bartelski, Jan; Kurzela, Miroslaw
2000-03-01
We have made next to leading order QCD fit to the deep inelastic spin asymmetries on nucleons and we have determined polarised quark and gluon densities. The functional form for such distributions was inspired by the Martin, Roberts and Stirling fit for unpolarised case. In addition to usually used data points (averaged over x and Q2) we have also considered the sample containing points with similar x and different Q2. It seems that splitting of quark densities into valence and sea contribution is strongly model dependent and only their sum (i.e. , Δ u and Δ d) can be precisely determined from the data. Integrated polarised gluon contribution, contrary to some expectations, is relatively small and the sign of it depends on the fact which sample of data points is used.
Mechanisms of Polarized Organelle Distribution in Neurons.
Britt, Dylan J; Farías, Ginny G; Guardia, Carlos M; Bonifacino, Juan S
2016-01-01
Neurons are highly polarized cells exhibiting axonal and somatodendritic domains with distinct complements of cytoplasmic organelles. Although some organelles are widely distributed throughout the neuronal cytoplasm, others are segregated to either the axonal or somatodendritic domains. Recent findings show that organelle segregation is largely established at a pre-axonal exclusion zone (PAEZ) within the axon hillock. Polarized sorting of cytoplasmic organelles at the PAEZ is proposed to depend mainly on their selective association with different microtubule motors and, in turn, with distinct microtubule arrays. Somatodendritic organelles that escape sorting at the PAEZ can be subsequently retrieved at the axon initial segment (AIS) by a microtubule- and/or actin-based mechanism. Dynamic sorting along the PAEZ-AIS continuum can thus explain the polarized distribution of cytoplasmic organelles between the axonal and somatodendritic domains.
Mechanisms of Polarized Organelle Distribution in Neurons
Britt, Dylan J.; Farías, Ginny G.; Guardia, Carlos M.; Bonifacino, Juan S.
2016-01-01
Neurons are highly polarized cells exhibiting axonal and somatodendritic domains with distinct complements of cytoplasmic organelles. Although some organelles are widely distributed throughout the neuronal cytoplasm, others are segregated to either the axonal or somatodendritic domains. Recent findings show that organelle segregation is largely established at a pre-axonal exclusion zone (PAEZ) within the axon hillock. Polarized sorting of cytoplasmic organelles at the PAEZ is proposed to depend mainly on their selective association with different microtubule motors and, in turn, with distinct microtubule arrays. Somatodendritic organelles that escape sorting at the PAEZ can be subsequently retrieved at the axon initial segment (AIS) by a microtubule- and/or actin-based mechanism. Dynamic sorting along the PAEZ-AIS continuum can thus explain the polarized distribution of cytoplasmic organelles between the axonal and somatodendritic domains. PMID:27065809
Generalized parton correlation functions for a spin-0 hadron
Meissner, Stephan; Metz, Andreas; Schlegel, Marc; Goeke, Klaus
2008-08-01
The fully unintegrated, off-diagonal quark-quark correlator for a spin-0 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects are of relevance for the phenomenology of certain hard exclusive reactions. In particular, they can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist.
BUNCE, G.; VIGDOR, S.
2001-03-15
International workshop on II Polarized Partons at High Q2 region 11 was held at the Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan on October 13-14, 2000, as a satellite of the international conference ''SPIN 2000'' (Osaka, Japan, October 16-21,2000). This workshop was supported by RIKEN (The Institute of Physical and Chemical Research) and by Yukawa Institute. The scientific program was focused on the upcoming polarized collider RHIC. The workshop was also an annual meeting of RHIC Spin Collaboration (RSC). The number of participants was 55, including 28 foreign visitors and 8 foreign-resident Japanese participants, reflecting the international nature of the RHIC spin program. At the workshop there were 25 oral presentations in four sessions, (1) RHIC Spin Commissioning, (2) Polarized Partons, Present and Future, (3) New Ideas on Polarization Phenomena, (4) Strategy for the Coming Spin Running. In (1) the successful polarized proton commissioning and the readiness of the accelerator for the physics program impressed us. In (2) and (3) active discussions were made on the new structure function to be firstly measured at RHIC, and several new theoretical ideas were presented. In session (4) we have established a plan for the beam time requirement toward the first collision of polarized protons. These proceedings include the transparencies presented at the workshop. The discussion on ''Strategy for the Coming Spin Running'' was summarized by the chairman of the session, S. Vigdor and G. Bunce.
NASA Astrophysics Data System (ADS)
Pasquini, B.; Schweitzer, P.
2014-07-01
At leading twist the transverse momentum dependent parton distributions of the pion consist of two functions, the unpolarized f1,π(x,k⊥2) and the Boer-Mulders function h1,π⊥(x ,k⊥2). We study both functions within a light-front constituent model of the pion, comparing the results with different pion models and the corresponding nucleon distributions from a light-front constituent model. After evolution from the model scale to the relevant experimental scales, the results for the collinear pion valence parton distribution function f1,π(x) are in very good agreement with available parametrizations. Using the light-front constituent model results for the Boer-Mulders functions of the pion and nucleon, we calculate the coefficient ν in the angular distribution of Drell-Yan dileptons produced in pion-nucleus scattering, which is responsible for the violation of the Lam-Tung relation. We find a good agreement with the data, and carefully discuss the range of applicability of our approach.
Guegan, Baptiste
2012-11-01
The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.
Perturbative QCD correlations in multi-parton collisions
NASA Astrophysics Data System (ADS)
Blok, B.; Dokshitzer, Yu.; Frankfurt, L.; Strikman, M.
2014-06-01
We examine the role played in double-parton interactions (DPI) by the parton-parton correlations originating from perturbative QCD parton splittings. Also presented are the results of the numerical analysis of the integrated DPI cross sections at Tevatron and LHC energies. To obtain the numerical results the knowledge of the single-parton GPDs gained by the HERA experiments was used to construct the non-perturbative input for generalized double-parton distributions. The perturbative two-parton correlations induced by three-parton interactions contribute significantly to a resolution of the longstanding puzzle of an excess of multi-jet production events in the back-to-back kinematics observed at the Tevatron.
Probe initial parton density and formation time via jet quenching
Wang, Xin-Nian
2002-09-20
Medium modification of jet fragmentation function due to multiple scattering and induced gluon radiation leads directly to jet quenching or suppression of leading particle distribution from jet fragmentation. One can extract an effective total parton energy loss which can be related to the total transverse momentum broadening. For an expanding medium, both are shown to be sensitive to the initial parton density and formation time. Therefore, one can extract the initial parton density and formation time from simultaneous measurements of parton energy loss and transverse momentum broadening. Implication of the recent experimental data on effects of detailed balance in parton energy loss is also discussed.
Constraining the Polarized Gluon Distribution Through Di-jet Measurements at √{ s} = 510 GeV at STAR
NASA Astrophysics Data System (ADS)
Olvitt, Daniel, Jr.; STAR Collaboration
2017-01-01
The production of jets from polarized p+p collisions at STAR is dominated by quark-gluon and gluon-gluon scattering. The di-jet double spin asymmetry (ALL) is sensitive to the polarized gluon distribution (ΔG). Di-jets are also advantageous because the parton momentum fraction, x, of initial partons may be reconstructed to first order from the final state measurements. Both jet and di-jet ALL measurements at √{ s} = 200 GeV have helped to constrain ΔG to values of x 0.05. In 2012, data were collected at √{ s} = 510 GeV in order to probe lower values of x. Jet and di-jet preliminary ALL results have been released and will soon be incorporated into theoretical fits. In 2013, data were also collected at √{ s} = 510 GeV. An update on the di-jet ALL measurement using polarized p+p data collected at STAR during 2013, with an estimated 250 pb-1 of integrated luminosity will be presented.
Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC
L. Frankfurt, M. Strikman, C. Weiss
2011-03-01
We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.
The midpoint between dipole and parton showers
Höche, Stefan; Prestel, Stefan
2015-09-28
We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A weighting algorithm is implemented that allows one to consistently treat potentially negative values of the splitting functions and the parton distributions. Thus, we provide two independent, publicly available implementations for the two event generators PYTHIA and SHERPA.
Phenomenological determination of polarized quark distributions in the nucleon
NASA Astrophysics Data System (ADS)
Bartelski, Jan; Tatur, Stanisław
1996-03-01
We present a fit to spin asymmetries which gives polarized quark distributions. These functions are closely related to the ones given by the Martin, Roberts and Stirling fit for unpolarized structure functions. The integrals of polarized distributions are discussed and compared with the corresponding quantities obtained from neutron and hyperon β-decay data. We use the combination of proton, neutron and deuteron spin asymmetries in order to determine the coefficients of our polarized quark distributions. Our fit shows that phenomenologically there is no need for taking polarized gluons into account.
Spin-flavor structure of chiral-odd generalized parton distributions in the large-${N}_{c}$ limit
Schweitzer, P.; Weiss, C.
2016-10-05
We study the spin-flavor structure of the nucleon's chiral-odd generalized parton distributions (transversity GPDs) in the large-N_{c} limit of QCD. In contrast to the chiral-even case, only three combinations of the four chiral-odd GPDs are nonzero in the leading order of the 1/N_{c} expansion: E-bar_{T} = E_{T}+2H-tilde_{T}, H_{T}, and E-tilde_{T}. The degeneracy is explained by the absence of spin-orbit interactions correlating the transverse momentum transfer with the transverse quark spin. It can also be deduced from the natural N_{c} scaling of the quark-nucleon helicity amplitudes associated with the GPDs. In the GPD E-bar_{T} the flavor-singlet component u+d is leading in the 1/N_{c} expansion, while in H_{T} and E-tilde_{T} it is the flavor-nonsinglet components u–d. Furthermore, the large-N_{c} relations are consistent with the spin-flavor structure extracted from hard exclusive π^{0} and η electroproduction data, if it is assumed that the processes are mediated by twist-3 amplitudes involving the chiral-odd GPDs and the chiral-odd pseudoscalar meson distribution amplitudes.
Hydrogen distribution in the lunar polar regions
NASA Astrophysics Data System (ADS)
Sanin, A. B.; Mitrofanov, I. G.; Litvak, M. L.; Bakhtin, B. N.; Bodnarik, J. G.; Boynton, W. V.; Chin, G.; Evans, L. G.; Harshman, K.; Fedosov, F.; Golovin, D. V.; Kozyrev, A. S.; Livengood, T. A.; Malakhov, A. V.; McClanahan, T. P.; Mokrousov, M. I.; Starr, R. D.; Sagdeev, R. Z.; Tret'yakov, V. I.; Vostrukhin, A. A.
2017-02-01
We present a method of conversion of the lunar neutron counting rate measured by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) instrument collimated neutron detectors, to water equivalent hydrogen (WEH) in the top ∼1 m layer of lunar regolith. Polar maps of the Moon's inferred hydrogen abundance are presented and discussed.
Nucleon Parton Structure from Continuum QCD
NASA Astrophysics Data System (ADS)
Bednar, Kyle; Cloet, Ian; Tandy, Peter
2017-01-01
The parton structure of the nucleon is investigated using QCD's Dyson-Schwinger equations (DSEs). This formalism builds in numerous essential features of QCD, for example, the dressing of parton propagators and dynamical formation of non-pointlike di-quark correlations. All needed elements of the approach, including the nucleon wave function solution from a Poincaré covariant Faddeev equation, are encoded in spectral-type representations in the Nakanishi style. This facilitates calculations and the necessary connections between Euclidean and Minkowski metrics. As a first step results for the nucleon quark distribution functions will be presented. The extension to the transverse momentum-dependent parton distributions (TMDs) also be discussed. Supported by NSF Grant No. PHY-1516138.
Polarization-multiplexed plasmonic phase generation with distributed nanoslits.
Lee, Seung-Yeol; Kim, Kyuho; Lee, Gun-Yeal; Lee, Byoungho
2015-06-15
Methods for multiplexing surface plasmon polaritons (SPPs) have been attracting much attention due to their potentials for plasmonic integrated systems, plasmonic holography, and optical tweezing. Here, using closely-distanced distributed nanoslits, we propose a method for generating polarization-multiplexed SPP phase profiles which can be applied for implementing general SPP phase distributions. Two independent types of SPP phase generation mechanisms - polarization-independent and polarization-reversible ones - are combined to generate fully arbitrary phase profiles for each optical handedness. As a simple verification of the proposed scheme, we experimentally demonstrate that the location of plasmonic focus can be arbitrary designed, and switched by the change of optical handedness.
Random distributed feedback Raman fiber laser with polarized pumping
NASA Astrophysics Data System (ADS)
Wu, H.; Wang, Z. N.; Churkin, D. V.; Vatnik, I. D.; Fan, M. Q.; Rao, Y. J.
2015-01-01
In this letter, the polarization properties of a random fiber laser operating via Raman gain and random distributed feedback owing to Rayleigh scattering are investigated for the first time. Using polarized pump, the partially polarized generation is obtained with a generation spectrum exhibiting discrete narrow spectral features contrary to the smooth spectrum observed for the depolarized pump. The threshold, output power, degree of polarization and the state of polarization (SOP) of the lasing can be significantly influenced by the SOP of the pump. Fine narrow spectral components are also sensitive to the SOP of the pump wave. Furthermore, we found that random lasing’s longitudinal power distributions are different in the case of polarized and depolarized pumping that results in considerable reduction of the generation slope efficiency for the polarized radiation. Our results indicate that polarization effects play an important role on the performance of the random fiber laser. This work improves the understanding of the physics of random lasing in fibers and makes a step forward towards the establishment of the vector model of random fiber lasers.
Parton Charge Symmetry Violation: Electromagnetic Effects and W Production Asymmetries
J.T. Londergan; D.P. Murdock; A.W. Thomas
2006-04-14
Recent phenomenological work has examined two different ways of including charge symmetry violation in parton distribution functions. First, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the magnitude of parton charge symmetry breaking. In a second approach, two groups have included the coupling of partons to photons in the QCD evolution equations. One possible experiment that could search for isospin violation in parton distributions is a measurement of the asymmetry in W production at a collider. In this work we include both of the postulated sources of parton charge symmetry violation. We show that, given charge symmetry violation of a magnitude consistent with existing high energy data, the expected W production asymmetries would be quite small, generally less than one percent.
Linearly polarized gluons and the Higgs transverse momentum distribution.
Boer, Daniël; den Dunnen, Wilco J; Pisano, Cristian; Schlegel, Marc; Vogelsang, Werner
2012-01-20
We study how gluons carrying linear polarization inside an unpolarized hadron contribute to the transverse momentum distribution of Higgs bosons produced in hadronic collisions. They modify the distribution produced by unpolarized gluons in a characteristic way that could be used to determine whether the Higgs boson is a scalar or a pseudoscalar particle.
NASA Astrophysics Data System (ADS)
Modarres, M.; Hosseinkhani, H.; Olanj, N.
2014-02-01
The aim of the present work is to study the phenomenological behavior of unitegrated parton distribution functions (UPDF) by using the Kimber-Martin-Ryskin (KMR) and Martin-Ryskin-Watt (MRW) formalisms. In the first method, the leading order (LO) UPDF of the KMR prescription is extracted, by taking into account the PDF of Martin et al., i.e., MSTW2008-LO and MRST99-NLO and. While in the second scheme, the next-to-leading order (NLO) UPDF of the (MRW) procedure is generated through the set of MSTW2008-NLO PDFas the inputs. The different aspects of the UPDF in the two approaches, as well as the input PDF are discussed. Then, the deep inelastic proton structure functions, F2(x,Q2), are calculated from the above UPDF in the two schemes, and compared with the data, which are extracted from the ZEUS, NMC, and H1+ZEUS experimental measurements. In general, it is shown that the calculated structure functions based on the UPDF of two schemes, are consistent to the experimental data, and by a good approximation, they are independent to the input PDF. But the proton structure functions, which are extracted from the KMR prescription, have better agreement to the data with respect to that of MRW. Although the MRW formalism is in more compliance with the Dokshitzer-Bribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation requisites, but it seems in the KMR case, the angular ordering constraint spreads the UPDF to the whole transverse momentum region, and makes the results to sum up the leading DGLAP and Balitski-Fadin-Kuraev-Lipatov (BFKL) Logarithms. This point is under study by the authors.
Accessing the Distribution of Linearly Polarized Gluons in Unpolarized Hadrons
Boer, Daniel; Brodsky, Stanley J.; Mulders, Piet J.; Pisano, Cristian; /Cagliari U. /INFN, Cagliari
2011-08-19
Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos2{phi} asymmetries in heavy quark pair or dijet production in electron-hadron collisions. Future Electron-Ion Collider (EIC) or Large Hadron electron Collider (LHeC) experiments are ideally suited for this purpose. Here we estimate the maximum asymmetries for EIC kinematics.
Are partons confined tachyons?
Noyes, H.P.
1996-03-01
The author notes that if hadrons are gravitationally stabilized ``black holes``, as discrete physics suggests, it is possible that partons, and in particular quarks, could be modeled as tachyons, i.e. particles having v{sup 2} > c{sup 2}, without conflict with the observational fact that neither quarks nor tachyons have appeared as ``free particles``. Some consequences of this model are explored.
Parton physics from large-momentum effective field theory
NASA Astrophysics Data System (ADS)
Ji, XiangDong
2014-07-01
Parton physics, when formulated as light-front correlations, are difficult to study non-perturbatively, despite the promise of light-front quantization. Recently an alternative approach to partons have been proposed by re-visiting original Feynman picture of a hadron moving at asymptotically large momentum. Here I formulate the approach in the language of an effective field theory for a large hadron momentum P in lattice QCD, LaMET for short. I show that using this new effective theory, parton properties, including light-front parton wave functions, can be extracted from lattice observables in a systematic expansion of 1/ P, much like that the parton distributions can be extracted from the hard scattering data at momentum scales of a few GeV.
Polarization of photons scattered by electrons in any spectral distribution
Chang, Zhe; Lin, Hai-Nan; Jiang, Yunguo
2014-01-01
On the basis of the quantum electrodynamics, we present a generic formalism of the polarization for beamed monochromatic photons scattered by electrons in any spectral distribution. The formulae reduce to the components of the Fano matrix when electrons are at rest. We mainly investigate the polarization in three scenarios, i.e., electrons at rest, isotropic electrons with a power-law spectrum, and thermal electrons. If the incident beam is polarized, the polarization is reduced significantly by isotropic electrons at large viewing angles; the degree of polarization caused by thermal electrons is about half of that caused by power-law electrons. If the incident bean is unpolarized, soft γ-rays can lead to about 15% polarization at viewing angles around π/4. For isotropic electrons, one remarkable feature is that the polarization as a function of the incident photon energy always peaks roughly at 1 MeV; this is valid for both the thermal and power-law cases. This feature can be used to distinguish the model of the inverse Compton scattering from that of the synchrotron radiation.
Resolution and polarization distribution in cryogenic DNP/MAS experiments
Barnes, Alexander B.; Corzilius, Björn; Mak-Jurkauskas, Melody L.; Andreas, Loren B.; Bajaj, Vikram S.; Matsuki, Yoh; Belenky, Marina L.; Lugtenburg, Johan; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Herzfeld, Judith; Griffin, Robert G.
2014-01-01
This contribution addresses four potential misconceptions associated with high-resolution dynamic nuclear polarization/magic angle spinning (DNP/MAS) experiments. First, spectral resolution is not generally compromised at the cryogenic temperatures at which DNP experiments are performed. As we demonstrate at a modest field of 9 T (380 MHz 1H), 1 ppm linewidths are observed in DNP/MAS spectra of a membrane protein in its native lipid bilayer, and <0.4 ppm linewidths are reported in a crystalline peptide at 85 K. Second, we address the concerns about paramagnetic broadening in DNP/MAS spectra of proteins by demonstrating that the exogenous radical polarizing agents utilized for DNP are distributed in the sample in such a manner as to avoid paramagnetic broadening and thus maintain full spectral resolution. Third, the enhanced polarization is not localized around the polarizing agent, but rather is effectively and uniformly dispersed throughout the sample, even in the case of membrane proteins. Fourth, the distribution of polarization from the electron spins mediated via spin diffusion between 1H–1H strongly dipolar coupled spins is so rapid that shorter magnetization recovery periods between signal averaging transients can be utilized in DNP/MAS experiments than in typical experiments performed at ambient temperature. PMID:20454732
Superthermal electron distribution measurements from polarized electron cyclotron emission
Luce, T.C.; Efthimion, P.C.; Fisch, N.J.
1988-06-01
Measurements of the superthermal electron distribution can be made by observing the polarized electron cyclotron emission. The emission is viewed along a constant magnetic field surface. This simplifies the resonance condition and gives a direct correlation between emission frequency and kinetic energy of the emitting electron. A transformation technique is formulated which determines the anisotropy of the distribution and number density of superthermals at each energy measured. The steady-state distribution during lower hybrid current drive and examples of the superthermal dynamics as the runaway conditions is varied are presented for discharges in the PLT tokamak. 15 refs., 8 figs.
Spatial Distribution of Pair Production Over the Pulsar Polar Cap
NASA Astrophysics Data System (ADS)
Belyaev, Mikhail A.; Parfrey, Kyle
2016-10-01
Using an analytic, axisymmetric approach that includes general relativity, coupled to a condition for pair production deduced from simulations, we derive general results about the spatial distribution of pair-producing field lines over the pulsar polar cap. In particular, we show that pair production on magnetic field lines operates over only a fraction of the polar cap for an aligned rotator for general magnetic field configurations, assuming the magnetic field varies spatially on a scale that is larger than the size of the polar cap. We compare our result to force-free simulations of a pulsar with a dipole surface field and find excellent agreement. Our work has implications for first-principles simulations of pulsar magnetospheres and for explaining observations of pulsed radio and high-energy emission.
Multi-user distribution of polarization entangled photon pairs
NASA Astrophysics Data System (ADS)
Trapateau, J.; Ghalbouni, J.; Orieux, A.; Diamanti, E.; Zaquine, I.
2015-10-01
We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.
Multi-user distribution of polarization entangled photon pairs
Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I.; Ghalbouni, J.
2015-10-14
We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.
NASA Astrophysics Data System (ADS)
Ozvenchuk, V.; Linnyk, O.; Gorenstein, M. I.; Bratkovskaya, E. L.; Cassing, W.
2013-02-01
We study the kinetic and chemical equilibration in “infinite” parton matter within the parton-hadron-string dynamics off-shell transport approach, which is based on a dynamical quasiparticle model (DQPM) for partons matched to reproduce lattice QCD results—including the partonic equation of state—in thermodynamic equilibrium. The “infinite” parton matter is simulated by a system of quarks and gluons within a cubic box with periodic boundary conditions, at various energy densities, initialized out of kinetic and chemical equilibrium. We investigate the approach of the system to equilibrium and the time scales for the equilibration of different observables. We, furthermore, study particle distributions in the strongly interacting quark-gluon plasma (sQGP) including partonic spectral functions, momentum distributions, abundances of the different parton species, and their fluctuations (scaled variance, skewness, and kurtosis) in equilibrium. We also compare the results of the microscopic calculations with the ansatz of the DQPM. It is found that the results of the transport calculations are in equilibrium well matched by the DQPM for quarks and antiquarks, while the gluon spectral function shows a slightly different shape due to the mass dependence of the gluon width generated by the explicit interactions of partons. The time scales for the relaxation of fluctuation observables are found to be shorter than those for the average values. Furthermore, in the local subsystem, a strong change of the fluctuation observables with the size of the local volume is observed. These fluctuations no longer correspond to those of the full system and are reduced to Poissonian distributions when the volume of the local subsystem becomes small.
Distributed measurement of birefringence dispersion in polarization-maintaining fibers.
Tang, Feng; Wang, Xiang-Zhao; Zhang, Yimo; Jing, Wencai
2006-12-01
A new method to measure the birefringence dispersion in high-birefringence polarization-maintaining fibers is presented using white-light interferometry. By analyzing broadening of low-coherence interferograms obtained in a scanning Michelson interferometer, the birefringence dispersion and its variation along different fiber sections are acquired with high sensitivity and accuracy. Birefringence dispersions of two PANDA fibers at their operation wavelength are measured to be 0.011 ps/(km nm) and 0.018 ps/(km nm), respectively. Distributed measurement capability of the method is also verified experimentally.
THE EFFECT OF THE DUST SIZE DISTRIBUTION ON ASTEROID POLARIZATION
Masiero, Joseph; Hartzell, Christine; Scheeres, Daniel J. E-mail: christine.hartzell@colorado.edu
2009-12-15
We have developed a theoretical description of how of an asteroid's polarization-phase curve will be affected by the removal of the dust from the surface due to a size-dependent phenomenon such as radiation pressure-driven escape of levitated particles. We test our calculations against new observations of four small (D {approx} 1 km) near-Earth asteroids (NEAs; (85236), (142348), (162900), and 2006 SZ{sub 217}) obtained with the Dual Beam Imaging Polarimeter on the University of Hawaii's 2.2 m telescope, as well as previous observations of (25143) Itokawa and (433) Eros. We find that the polarization of the light reflected from an asteroid is controlled by the mineralogical and chemical composition of the surface and is independent of dust particle. The relation between the slope of the polarization-phase curve beyond the inversion angle and the albedo of an asteroid is thus independent of the surface regolith size distribution and is valid for both Main Belt and NEAs.
NASA Astrophysics Data System (ADS)
Modarres, M.; Masouminia, M. R.; Aminzadeh Nik, R.; Hosseinkhani, H.; Olanj, N.
2016-10-01
In a series of papers, we have investigated the compatibility of the Kimber-Martin-Ryskin (KMR) and Martin-Ryskin-Watt (MRW) unintegrated parton distribution functions (UPDFs) as well as the description of the experimental data on the proton structure functions. The present work is a sequel to that survey, via calculation of the transverse-momentum distribution of the electroweak gauge vector bosons in the kt-factorization scheme, by the means of the KMR, the leading-order (LO) MRW, and the next-to-leading-order (NLO) MRW UPDF, in the NLO. To this end, we have calculated and aggregated the invariant amplitudes of the corresponding involved diagrams in the NLO and counted the individual contributions in different frameworks. The preparation process for the UPDF utilizes the parton distribution functions of Martin et al., MSTW2008-LO, MSTW2008-NLO, MMHT2014-LO, and MMHT2014-NLO, as the inputs. Afterward, the results have been analyzed against each other as well as the existing experimental data, i.e., D0, CDF, ATLAS, and CMS collaborations. Our calculations show excellent agreement with the experiment data. It is, however, interesting to point out that the calculation using the KMR framework illustrates a stronger agreement with the experimental data, despite the fact that the LO MRW and the NLO MRW formalisms employ a better theoretical description of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equation. This is of course due to the use of the different implementation of the angular ordering constraint in the KMR approach, which automatically includes the resummation of ln (1 /x ) , Balitski-Fadin-Kuraev-Lipatov logarithms, in the LO Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equation.
Generalized parton correlation functions for a spin-1/2 hadron
Stephan Meissner, Andreas Metz, Marc Schlegel
2009-08-01
The fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects, in particular, can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. We find that none of these relations can be promoted to a model-independent status. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist. The present paper is a natural extension of our previous corresponding analysis for spin-0 hadrons.
Fourier analysis of polar cap electric field and current distributions
NASA Technical Reports Server (NTRS)
Barbosa, D. D.
1984-01-01
A theoretical study of high-latitude electric fields and currents, using analytic Fourier analysis methods, is conducted. A two-dimensional planar model of the ionosphere with an enhanced conductivity auroral belt and field-aligned currents at the edges is employed. Two separate topics are treated. A field-aligned current element near the cusp region of the polar cap is included to investigate the modifications to the convection pattern by the east-west component of the interplanetary magnetic field. It is shown that a sizable one-cell structure is induced near the cusp which diverts equipotential contours to the dawnside or duskside, depending on the sign of the cusp current. This produces characteristic dawn-dusk asymmetries to the electric field that have been previously observed over the polar cap. The second topic is concerned with the electric field configuration obtained in the limit of perfect shielding, where the field is totally excluded equatorward of the auroral oval. When realistic field-aligned current distributions are used, the result is to produce severely distorted, crescent-shaped equipotential contours over the cap. Exact, analytic formulae applicable to this case are also provided.
Implications of current constraints on parton charge symmetry
J. T. Londergan; A. W. Thomas
2005-11-01
For the first time, charge symmetry breaking terms in parton distribution functions have been included in a global fit to high energy data. We review the results obtained for both valence and sea quark charge symmetry violation and compare these results with the most stringent experimental upper limits on charge symmetry violation for parton distribution functions, as well as with theoretical estimates of charge symmetry violation. The limits allowed in the global fit would tolerate a rather large violation of charge symmetry. We discuss the implications of this for various observables, including extraction of the Weinberg angle in neutrino DIS and the Gottfried and Adler sum rules.
Parton fragmentation functions
NASA Astrophysics Data System (ADS)
Metz, A.; Vossen, A.
2016-11-01
The field of fragmentation functions of light quarks and gluons is reviewed. In addition to integrated fragmentation functions, attention is paid to the dependence of fragmentation functions on transverse momenta and on polarization degrees of freedom. Higher-twist and di-hadron fragmentation functions are considered as well. Moreover, the review covers both theoretical and experimental developments in hadron production in electron-positron annihilation, deep-inelastic lepton-nucleon scattering, and proton-proton collisions.
Biodiversity and distribution of polar freshwater DNA viruses
Aguirre de Cárcer, Daniel; López-Bueno, Alberto; Pearce, David A.; Alcamí, Antonio
2015-01-01
Viruses constitute the most abundant biological entities and a large reservoir of genetic diversity on Earth. Despite the recent surge in their study, our knowledge on their actual biodiversity and distribution remains sparse. We report the first metagenomic analysis of Arctic freshwater viral DNA communities and a comparative analysis with other freshwater environments. Arctic viromes are dominated by unknown and single-stranded DNA viruses with no close relatives in the database. These unique viral DNA communities mostly relate to each other and present some minor genetic overlap with other environments studied, including an Arctic Ocean virome. Despite common environmental conditions in polar ecosystems, the Arctic and Antarctic DNA viromes differ at the fine-grain genetic level while sharing a similar taxonomic composition. The study uncovers some viral lineages with a bipolar distribution, suggesting a global dispersal capacity for viruses, and seemingly indicates that viruses do not follow the latitudinal diversity gradient known for macroorganisms. Our study sheds light into the global biogeography and connectivity of viral communities. PMID:26601189
Parton interpretation of the nucleon spin-dependent structure functions
Mankiewicz, L. ); Ryzak, Z. )
1991-02-01
We discuss the interpretation of the nucleon's polarized structure function {ital g}{sub 2}({ital x}). If the target state is represented by its Fock decomposition on the light cone, the operator-product expansion allows us to demonstrate that moments of {ital g}{sub 2}({ital x}) are related to overlap integrals between wave functions of opposite longitudinal polarizations. In the light-cone formalism such wave functions are related by the kinematical operator {ital scrY}, or light-cone parity. As a consequence, it can be shown that moments of {ital g}{sub 2} give information about the same parton wave function, or probability amplitude to find a certain parton configuration in the target which defines {ital g}{sub 1}({ital x}) or {ital F}{sub 2}({ital x}). Specific formulas are given, and possible applications to the phenomenology of the nucleon structure in QCD are discussed.
Threshold photoneutron angular distribution and polarization studies of nuclei
Holt, R.J.
1980-01-01
The photoneutron method was applied to the study of: (1) deuteron photodisintegration; (2) giant magnetic dipole resonances in heavy nuclei; (3) mechanism of radiative capture in light nuclei; and (4) isospin splitting of the giant dipole resonance in /sup 60/Ni. These studies were performed with the pulsed bremsstrahlung beam and high-resolution spectrometer available at the Argonne high-current electron linac. A threshold photoneutron polarization method was developed in order to search for the giant M1 resonance in heavy nuclei. A surprisingly small amount of M1 strength was found in /sup 208/Pb. Furthermore, the M1 strength for the 5.08-MeV excitation in /sup 17/O, the best example of a single-particle M1 resonance in nuclei, was found to be strongly quenched. In addition, the /sup 17/O(..gamma..,n/sub 0/)/sup 16/O reaction was found to provide an ideal example of the Lane-Lynn theory of radiative capture. The interplay among the three components of the theory, internal, channel and potential capture, were evident from the data. An electron beam transport system was developed which allows the bremsstrahlung to impinge on the photoneutron target on an axis perpendicular to the usual reaction plane. This system provides an accurate method for the measurement of relative angular distributions in (..gamma..,n) reactions. This system was applied to a high-accuracy measurement of the relative angular distribution for the D(..gamma..,n)H reaction. The question of isospin-splitting of the giant dipole resonance in /sup 60/Ni was studied by using the unique pico-pulse from the accelerator and the newly installed 25-m, neutron flight paths. The results provide clear evidence for the effect of isospin splitting.
NASA Astrophysics Data System (ADS)
Walker, Nick; Fleming, Andrew; Cziferszky, Andreas; Toudal Pedersen, Leif; Rasmussen, Till; Makynen, Marko; Berglund, Robin; Seitsonen, Lauri; Rudjord, Oystein; Solberg, Rune; Tangen, Helge; Axell, Lars; Saldo, Roberto; Melsheimer, Christian; Larsen, Hans Eilif; Puestow, Thomas; Arhturs, David; Flach, Dominie
2016-08-01
The POLAR ICE project has developed a system for integrating and delivering satellite derived ice information products to operators working in the economically and environmentally important Arctic and Antarctic regions. POLAR ICE has been supported by the European Commission's FP7 programme and undertaken by European and Canadian companies and institutes, who are all partners in the Polar View Earth Observation Limited (PVEO) company. It is the aim of PVEO to commercialise the service that has been developed and demonstrated as a part of POLAR ICE.Access to sea ice information derived from satellite earth observation data is critical to support the increasing numbers of Arctic and Antarctic shipping and off-shore operations and to protect the rapidly changing polar environment.To-date the development of sea ice information capabilities has addressed separate elements of complete service chains. In contrast POLAR ICE has linked these separate elements together, filled in known gaps and built a robust integrated service chain.
Recent Results on Polarized Quark and Gluon Distributions at Compass
NASA Astrophysics Data System (ADS)
Savin, I.; Jinr; Dubna
2005-04-01
The latest results of deep inelastic scattering (DIS) studies of 160 GeV muons on the deuterated polarized target are reported. They include estimations of virtual photon-deuteron asymmetries, gluon contributions to the nucleon spin and Collins asymmetries in hadron production on the transversely polarized target.
NASA Astrophysics Data System (ADS)
Yamanishi, Teruya; Yu-Bing, Dong; Morii, Toshiyuki
2001-06-01
To study the polarized gluon density Δg(x) in the nucleon, we propose the high-pT pair charmed hadron production process in polarized lp scattering. The double spin asymmetry ALL for this process is a good observable for testing the models of Δg(x). .
Emergent phenomena and partonic structure in hadrons
NASA Astrophysics Data System (ADS)
Roberts, Craig D.; Mezrag, Cédric
2017-03-01
Modern facilities are poised to tackle fundamental questions within the Standard Model, aiming to reveal the nature of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between these two, key emergent phenomena. There is strong evidence to suggest that they are intimately connected with the appearance of momentum-dependent masses for gluons and quarks in QCD, which are large in the infrared: mg 500MeV and Mq 350MeV. DCSB, expressed in the dynamical generation of a dressed-quark mass, has an enormous variety of verifiable consequences, including an enigmatic result that the properties of the (almost) massless pion are the cleanest expression of the mechanism which is responsible for almost all the visible mass in the Universe. This contribution explains that these emergent phenomena are expressed with particular force in the partonic structure of hadrons, e.g. in valence-quark parton distribution amplitudes and functions, and, consequently, in numerous hadronic observables, so that we are now in a position to exhibit the consequences of confinement and DCSB in a wide range of hadron observables, opening the way to empirical verification of their expression in the Standard Model.
Movements and distribution of polar bears in the Beaufort sea
Amstrup, Steven C.; Durner, G.M.; Stirling, I.; Lunn, N.J.; Messier, F.
2000-01-01
We fitted 173 satellite radio collars (platform transmitter terminals) to 121 adult female polar bears in the Beaufort Sea and relocated the bears 44 736 times between 1985 and 1995. We regularly resighted many instrumented bears so that we could ascertain whether changes in movements or distribution were related to reproductive status. Mean short-term movement rates were less than 2 km/h for all classes of bears. Maximum movement rates occurred in winter and early summer. In the southern Beaufort Sea (SBS), net geographic movements from the beginning to the end of each month were smaller for females with cubs of the year than for solitary females, and larger in November than in April, May, or July. In May, June, July, and August, radio-collared bears in the SBS moved north. They moved south in October. In the northern Beaufort Sea (NBS), bears moved north in June and south in March and September. Total annual movements ranged from 1406 to 6203 km. Mean total distances moved each month ranged from 79 to 420 km. Total monthly movements by SBS bears were largest in early winter and smallest in early spring. In the NBS, movements were largest in summer and smallest in winter. In the SBS, females with cubs moved less each month than other females. Annual activity areas ranged from 7264 to 596 800 km2. Monthly activity areas ranged from 88 to 9760 km2. Seasonal fidelity to activity areas of bears captured in all parts of the Beaufort Sea was strongest in summer and weakest in spring.
Buica, Gabriela; Nakajima, Takashi
2005-11-15
We theoretically investigate the effects of laser polarization on the photoelectron angular distribution through laser-induced continuum structure. We focus on a polarization geometry where the probe and dressing lasers are both linearly polarized and change the relative polarization angle between them. We find that the total ionization yield and the branching ratio into different ionization channels change as a function of the relative polarization angle, and accordingly the photoelectron angular distribution is altered. We present specific results for the 4p{sub 1/2}-6p{sub 1/2} and 4p{sub 3/2}-6p{sub 3/2} systems of the K atom and show that the change of the polarization angle leads to a significant modification of the photoelectron angular distribution.
Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hartl, C; Hörmann, N; Hrubec, J; Jeitler, M; Kiesenhofer, W; Knünz, V; Krammer, M; Krätschmer, I; Liko, D; Mikulec, I; Rabady, D; Rahbaran, B; Rohringer, H; Schöfbeck, R; Strauss, J; Treberer-Treberspurg, W; Waltenberger, W; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Alderweireldt, S; Bansal, M; Bansal, S; Cornelis, T; De Wolf, E A; Janssen, X; Knutsson, A; Luyckx, S; Ochesanu, S; Rougny, R; Van De Klundert, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Van Spilbeeck, A; Blekman, F; Blyweert, S; D'Hondt, J; Daci, N; Heracleous, N; Keaveney, J; Lowette, S; Maes, M; Olbrechts, A; Python, Q; Strom, D; Tavernier, S; Van Doninck, W; Van Mulders, P; Van Onsem, G P; Villella, I; Caillol, C; Clerbaux, B; De Lentdecker, G; Dobur, D; Favart, L; Gay, A P R; Grebenyuk, A; Léonard, A; Mohammadi, A; Perniè, L; Reis, T; Seva, T; Thomas, L; Vander Velde, C; Vanlaer, P; Wang, J; Zenoni, F; Adler, V; Beernaert, K; Benucci, L; Cimmino, A; Costantini, S; Crucy, S; Dildick, S; Fagot, A; Garcia, G; Mccartin, J; Ocampo Rios, A A; Ryckbosch, D; Salva Diblen, S; Sigamani, M; Strobbe, N; Thyssen, F; Tytgat, M; Yazgan, E; Zaganidis, N; Basegmez, S; Beluffi, C; Bruno, G; Castello, R; Caudron, A; Ceard, L; Da Silveira, G G; Delaere, C; du Pree, T; Favart, D; Forthomme, L; Giammanco, A; Hollar, J; Jafari, A; Jez, P; Komm, M; Lemaitre, V; Nuttens, C; Pagano, D; Perrini, L; Pin, A; Piotrzkowski, K; Popov, A; Quertenmont, L; Selvaggi, M; Vidal Marono, M; Vizan Garcia, J M; Beliy, N; Caebergs, T; Daubie, E; Hammad, G H; Júnior, W L Aldá; Alves, G A; Brito, L; Correa Martins Junior, M; Martins, T Dos Reis; Mora Herrera, C; Pol, M E; Carvalho, W; Chinellato, J; Custódio, A; Da Costa, E M; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Malbouisson, H; Matos Figueiredo, D; Mundim, L; Nogima, H; Prado Da Silva, W L; Santaolalla, J; Santoro, A; Sznajder, A; Tonelli Manganote, E J; Vilela Pereira, A; Bernardes, C A; Dogra, S; Fernandez Perez Tomei, T R; Gregores, E M; Mercadante, P G; Novaes, S F; Padula, Sandra S; Aleksandrov, A; Genchev, V; Iaydjiev, P; Marinov, A; Piperov, S; Rodozov, M; Stoykova, S; Sultanov, G; Vutova, M; Dimitrov, A; Glushkov, I; Hadjiiska, R; Kozhuharov, V; Litov, L; Pavlov, B; Petkov, P; Bian, J G; Chen, G M; Chen, H S; Chen, M; Du, R; Jiang, C H; Plestina, R; Romeo, F; Tao, J; Wang, Z; Asawatangtrakuldee, C; Ban, Y; Li, Q; Liu, S; Mao, Y; Qian, S J; Wang, D; Zou, W; Avila, C; Chaparro Sierra, L F; Florez, C; Gomez, J P; Gomez Moreno, B; Sanabria, J C; Godinovic, N; Lelas, D; Polic, D; Puljak, I; Antunovic, Z; Kovac, M; Brigljevic, V; Kadija, K; Luetic, J; Mekterovic, D; Sudic, L; Attikis, A; Mavromanolakis, G; Mousa, J; Nicolaou, C; Ptochos, F; Razis, P A; Bodlak, M; Finger, M; Finger, M; Assran, Y; Ellithi Kamel, A; Mahmoud, M A; Radi, A; Kadastik, M; Murumaa, M; Raidal, M; Tiko, A; Eerola, P; Fedi, G; Voutilainen, M; Härkönen, J; Karimäki, V; Kinnunen, R; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Peltola, T; Tuominen, E; Tuominiemi, J; Tuovinen, E; Wendland, L; Talvitie, J; Tuuva, T; Besancon, M; Couderc, F; Dejardin, M; Denegri, D; Fabbro, B; Faure, J L; Favaro, C; Ferri, F; Ganjour, S; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Locci, E; Malcles, J; Rander, J; Rosowsky, A; Titov, M; Baffioni, S; Beaudette, F; Busson, P; Charlot, C; Dahms, T; Dalchenko, M; Dobrzynski, L; Filipovic, N; Florent, A; Granier de Cassagnac, R; Mastrolorenzo, L; Miné, P; Mironov, C; Naranjo, I N; Nguyen, M; Ochando, C; Paganini, P; Regnard, S; Salerno, R; Sauvan, J B; Sirois, Y; Veelken, C; Yilmaz, Y; Zabi, A; Agram, J-L; Andrea, J; Aubin, A; Bloch, D; Brom, J-M; Chabert, E C; Collard, C; Conte, E; Fontaine, J-C; Gelé, D; Goerlach, U; Goetzmann, C; Le Bihan, A-C; Van Hove, P; Gadrat, S; Beauceron, S; Beaupere, N; Boudoul, G; Bouvier, E; Brochet, S; Carrillo Montoya, C A; Chasserat, J; Chierici, R; Contardo, D; Depasse, P; El Mamouni, H; Fan, J; Fay, J; Gascon, S; Gouzevitch, M; Ille, B; Kurca, T; Lethuillier, M; Mirabito, L; Perries, S; Ruiz Alvarez, J D; Sabes, D; Sgandurra, L; Sordini, V; Vander Donckt, M; Verdier, P; Viret, S; Xiao, H; Tsamalaidze, Z; Autermann, C; Beranek, S; Bontenackels, M; Edelhoff, M; Feld, L; Hindrichs, O; Klein, K; Ostapchuk, A; Perieanu, A; Raupach, F; Sammet, J; Schael, S; Weber, H; Wittmer, B; Zhukov, V; Ata, M; Brodski, M; Dietz-Laursonn, E; Duchardt, D; Erdmann, M; Fischer, R; Güth, A; Hebbeker, T; Heidemann, C; Hoepfner, K; Klingebiel, D; Knutzen, S; Kreuzer, P; Merschmeyer, M; Meyer, A; Millet, P; Olschewski, M; Padeken, K; Papacz, P; Reithler, H; Schmitz, S A; Sonnenschein, L; Teyssier, D; Thüer, S; Weber, M; Cherepanov, V; Erdogan, Y; Flügge, G; Geenen, H; Geisler, M; Haj Ahmad, W; Heister, A; Hoehle, F; Kargoll, B; Kress, T; Kuessel, Y; Künsken, A; Lingemann, J; Nowack, A; Nugent, I M; Perchalla, L; Pooth, O; Stahl, A; Asin, I; Bartosik, N; Behr, J; Behrenhoff, W; Behrens, U; Bell, A J; Bergholz, M; Bethani, A; Borras, K; Burgmeier, A; Cakir, A; Calligaris, L; Campbell, A; Choudhury, S; Costanza, F; Diez Pardos, C; Dooling, S; Dorland, T; Eckerlin, G; Eckstein, D; Eichhorn, T; Flucke, G; Garcia, J Garay; Geiser, A; Gunnellini, P; Hauk, J; Hempel, M; Horton, D; Jung, H; Kalogeropoulos, A; Kasemann, M; Katsas, P; Kieseler, J; Kleinwort, C; Krücker, D; Lange, W; Leonard, J; Lipka, K; Lobanov, A; Lohmann, W; Lutz, B; Mankel, R; Marfin, I; Melzer-Pellmann, I-A; Meyer, A B; Mittag, G; Mnich, J; Mussgiller, A; Naumann-Emme, S; Nayak, A; Novgorodova, O; Ntomari, E; Perrey, H; Pitzl, D; Placakyte, R; Raspereza, A; Ribeiro Cipriano, P M; Roland, B; Ron, E; Sahin, M Ö; Salfeld-Nebgen, J; Saxena, P; Schmidt, R; Schoerner-Sadenius, T; Schröder, M; Seitz, C; Spannagel, S; Vargas Trevino, A D R; Walsh, R; Wissing, C; Aldaya Martin, M; Blobel, V; Centis Vignali, M; Draeger, A R; Erfle, J; Garutti, E; 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Musienko, Y; Nahn, S; Newman-Holmes, C; O'Dell, V; Prokofyev, O; Sexton-Kennedy, E; Sharma, S; Soha, A; Spalding, W J; Spiegel, L; Taylor, L; Tkaczyk, S; Tran, N V; Uplegger, L; Vaandering, E W; Vidal, R; Whitbeck, A; Whitmore, J; Yang, F; Acosta, D; Avery, P; Bortignon, P; Bourilkov, D; Carver, M; Cheng, T; Curry, D; Das, S; De Gruttola, M; Di Giovanni, G P; Field, R D; Fisher, M; Furic, I K; Hugon, J; Konigsberg, J; Korytov, A; Kypreos, T; Low, J F; Matchev, K; Milenovic, P; Mitselmakher, G; Muniz, L; Rinkevicius, A; Shchutska, L; Snowball, M; Sperka, D; Yelton, J; Zakaria, M; Hewamanage, S; Linn, S; Markowitz, P; Martinez, G; Rodriguez, J L; Adams, T; Askew, A; Bochenek, J; Diamond, B; Haas, J; Hagopian, S; Hagopian, V; Johnson, K F; Prosper, H; Veeraraghavan, V; Weinberg, M; Baarmand, M M; Hohlmann, M; Kalakhety, H; Yumiceva, F; Adams, M R; Apanasevich, L; Bazterra, V E; Berry, D; Betts, R R; Bucinskaite, I; Cavanaugh, R; Evdokimov, O; Gauthier, L; Gerber, C E; Hofman, D J; Khalatyan, S; Kurt, P; Moon, D H; O'Brien, C; Silkworth, C; Turner, P; Varelas, N; Bilki, B; Clarida, W; Dilsiz, K; Duru, F; Haytmyradov, M; Merlo, J-P; Mermerkaya, H; Mestvirishvili, A; Moeller, A; Nachtman, J; Ogul, H; Onel, Y; Ozok, F; Penzo, A; Rahmat, R; Sen, S; Tan, P; Tiras, E; Wetzel, J; Yi, K; Barnett, B A; Blumenfeld, B; Bolognesi, S; Fehling, D; Gritsan, A V; Maksimovic, P; Martin, C; Swartz, M; Baringer, P; Bean, A; Benelli, G; Bruner, C; Kenny, R P; Malek, M; Murray, M; Noonan, D; Sanders, S; Sekaric, J; Stringer, R; Wang, Q; Wood, J S; Chakaberia, I; Ivanov, A; Khalil, S; Makouski, M; Maravin, Y; Saini, L K; Shrestha, S; Skhirtladze, N; Svintradze, I; Gronberg, J; Lange, D; Rebassoo, F; Wright, D; Baden, A; Belloni, A; Calvert, B; Eno, S C; Gomez, J A; Hadley, N J; Kellogg, R G; Kolberg, T; Lu, Y; Marionneau, M; Mignerey, A C; Pedro, K; Skuja, A; Tonjes, M B; Tonwar, S C; Apyan, A; Barbieri, R; Bauer, G; Busza, W; Cali, I A; Chan, M; Di Matteo, L; Gomez Ceballos, G; Goncharov, M; Gulhan, D; Klute, M; Lai, Y S; Lee, Y-J; Levin, A; Luckey, P D; Ma, T; Paus, C; Ralph, D; Roland, C; Roland, G; Stephans, G S F; Stöckli, F; Sumorok, K; Velicanu, D; Veverka, J; Wyslouch, B; Yang, M; Zanetti, M; Zhukova, V; Dahmes, B; Gude, A; Kao, S C; Klapoetke, K; Kubota, Y; Mans, J; Pastika, N; Rusack, R; Singovsky, A; Tambe, N; Turkewitz, J; Acosta, J G; Oliveros, S; Avdeeva, E; Bloom, K; Bose, S; Claes, D R; Dominguez, A; Gonzalez Suarez, R; Keller, J; Knowlton, D; Kravchenko, I; Lazo-Flores, J; Malik, S; Meier, F; Snow, G R; Zvada, M; Dolen, J; Godshalk, A; Iashvili, I; Kharchilava, A; Kumar, A; Rappoccio, S; Alverson, G; Barberis, E; Baumgartel, D; Chasco, M; Haley, J; Massironi, A; Morse, D M; Nash, D; Orimoto, T; Trocino, D; Wang, R J; Wood, D; Zhang, J; Hahn, K A; Kubik, A; Mucia, N; Odell, N; Pollack, B; Pozdnyakov, A; Schmitt, M; Stoynev, S; Sung, K; Velasco, M; Won, S; Brinkerhoff, A; Chan, K M; Drozdetskiy, A; Hildreth, M; Jessop, C; Karmgard, D J; Kellams, N; Lannon, K; Luo, W; Lynch, S; Marinelli, N; Pearson, T; Planer, M; Ruchti, R; Valls, N; Wayne, M; Wolf, M; Woodard, A; Antonelli, L; Brinson, J; Bylsma, B; Durkin, L S; Flowers, S; Hart, A; Hill, C; Hughes, R; Kotov, K; Ling, T Y; Puigh, D; Rodenburg, M; Smith, G; Winer, B L; Wolfe, H; Wulsin, H W; Driga, O; Elmer, P; Hardenbrook, J; Hebda, P; Hunt, A; Koay, S A; Lujan, P; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Quan, X; Saka, H; Stickland, D; Tully, C; Werner, J S; Zuranski, A; Brownson, E; Mendez, H; Ramirez Vargas, J E; Barnes, V E; Benedetti, D; Bortoletto, D; De Mattia, M; Gutay, L; Hu, Z; Jha, M K; Jones, M; Jung, K; Kress, M; Leonardo, N; Lopes Pegna, D; Maroussov, V; Miller, D H; Neumeister, N; Radburn-Smith, B C; Shi, X; Shipsey, I; Silvers, D; Svyatkovskiy, A; Wang, F; Xie, W; Xu, L; Yoo, H D; Zablocki, J; Zheng, Y; Parashar, N; Stupak, J; Adair, A; Akgun, B; Ecklund, K M; Geurts, F J M; Li, W; Michlin, B; Padley, B P; Redjimi, R; Roberts, J; Zabel, J; Betchart, B; Bodek, A; Covarelli, R; de Barbaro, P; Demina, R; Eshaq, Y; Ferbel, T; Garcia-Bellido, A; Goldenzweig, P; Han, J; Harel, A; Khukhunaishvili, A; Petrillo, G; Vishnevskiy, D; Ciesielski, R; Demortier, L; Goulianos, K; Lungu, G; Mesropian, C; Arora, S; Barker, A; Chou, J P; Contreras-Campana, C; Contreras-Campana, E; Duggan, D; Ferencek, D; Gershtein, Y; Gray, R; Halkiadakis, E; Hidas, D; Kaplan, S; Lath, A; Panwalkar, S; Park, M; Patel, R; Salur, S; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Thomassen, P; Walker, M; Rose, K; Spanier, S; York, A; Bouhali, O; Castaneda Hernandez, A; Eusebi, R; Flanagan, W; Gilmore, J; Kamon, T; Khotilovich, V; Krutelyov, V; Montalvo, R; Osipenkov, I; Pakhotin, Y; Perloff, A; Roe, J; Rose, A; Safonov, A; Sakuma, T; Suarez, I; Tatarinov, A; Akchurin, N; Cowden, C; Damgov, J; Dragoiu, C; Dudero, P R; Faulkner, J; Kovitanggoon, K; Kunori, S; Lee, S W; Libeiro, T; Volobouev, I; Appelt, E; Delannoy, A G; Greene, S; Gurrola, A; Johns, W; Maguire, C; Mao, Y; Melo, A; Sharma, M; Sheldon, P; Snook, B; Tuo, S; Velkovska, J; Arenton, M W; Boutle, S; Cox, B; Francis, B; Goodell, J; Hirosky, R; Ledovskoy, A; Li, H; Lin, C; Neu, C; Wood, J; Clarke, C; Harr, R; Karchin, P E; Kottachchi Kankanamge Don, C; Lamichhane, P; Sturdy, J; Belknap, D A; Carlsmith, D; Cepeda, M; Dasu, S; Dodd, L; Duric, S; Friis, E; Hall-Wilton, R; Herndon, M; Hervé, A; Klabbers, P; Lanaro, A; Lazaridis, C; Levine, A; Loveless, R; Mohapatra, A; Ojalvo, I; Perry, T; Pierro, G A; Polese, G; Ross, I; Sarangi, T; Savin, A; Smith, W H; Taylor, D; Verwilligen, P; Vuosalo, C; Woods, N
The inclusive jet cross section for proton-proton collisions at a centre-of-mass energy of 7[Formula: see text] was measured by the CMS Collaboration at the LHC with data corresponding to an integrated luminosity of 5.0[Formula: see text]. The measurement covers a phase space up to 2[Formula: see text] in jet transverse momentum and 2.5 in absolute jet rapidity. The statistical precision of these data leads to stringent constraints on the parton distribution functions of the proton. The data provide important input for the gluon density at high fractions of the proton momentum and for the strong coupling constant at large energy scales. Using predictions from perturbative quantum chromodynamics at next-to-leading order, complemented with electroweak corrections, the constraining power of these data is investigated and the strong coupling constant at the Z boson mass [Formula: see text] is determined to be [Formula: see text], which is in agreement with the world average.
Khachatryan, Vardan
2015-06-26
The inclusive jet cross section for proton–proton collisions at a centre-of-mass energy of 7TeVwas measured by the CMS Collaboration at the LHC with data corresponding to an integrated luminosity of 5.0fb-1. The measurement covers a phase space up to 2TeV in jet transverse momentum and 2.5 in absolute jet rapidity. The statistical precision of these data leads to stringent constraints on the parton distribution functions of the proton. The data provide important input for the gluon density at high fractions of the proton momentum and for the strong coupling constant at large energy scales. Using predictions from perturbative quantum chromodynamicsmore » at next-to-leading order, complemented with electroweak corrections, the constraining power of these data is investigated and the strong coupling constant at the Z boson mass MZ is determined to be αS(MZ)=0.1185±0.0019(exp)+0.0060-0.0037(theo), which is in agreement with the world average.« less
Khachatryan, Vardan
2015-06-26
The inclusive jet cross section for proton–proton collisions at a centre-of-mass energy of 7TeVwas measured by the CMS Collaboration at the LHC with data corresponding to an integrated luminosity of 5.0fb^{-1}. The measurement covers a phase space up to 2TeV in jet transverse momentum and 2.5 in absolute jet rapidity. The statistical precision of these data leads to stringent constraints on the parton distribution functions of the proton. The data provide important input for the gluon density at high fractions of the proton momentum and for the strong coupling constant at large energy scales. Using predictions from perturbative quantum chromodynamics at next-to-leading order, complemented with electroweak corrections, the constraining power of these data is investigated and the strong coupling constant at the Z boson mass M_{Z} is determined to be α_{S}(M_{Z})=0.1185±0.0019(exp)^{+0.0060}_{-0.0037}(theo), which is in agreement with the world average.
NASA Astrophysics Data System (ADS)
Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bai, X.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Bathe, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Cronin, N.; Crossette, N.; Csanád, M.; Csörgő, T.; Dairaku, S.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; Donadelli, M.; D'Orazio, L.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Edwards, S.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; Hayano, R.; Hayashi, S.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Horaguchi, T.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ichihara, T.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imazu, Y.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kihara, K.; Kijima, K. M.; Kim, B. I.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, H.-J.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kimelman, B.; Kinney, E.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, G. H.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Midori, J.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Mohapatra, S.; Montuenga, P.; Moon, H. J.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nukariya, A.; Nyanin, A. S.; Obayashi, H.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J. S.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Pei, H.; Peng, J.-C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Rinn, T.; Riveli, N.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sekiguchi, Y.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shaver, A.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slunečka, M.; Snowball, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Stone, M. R.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, C. L.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Voas, B.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; White, A. S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. H.; Yoon, I.; You, Z.; Younus, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Zou, L.; Phenix Collaboration
2016-03-01
We present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from W±/Z decays, produced in longitudinally polarized p +p collisions at center of mass energies of √{s }=500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the W -boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb-1 , which exceeds previous PHENIX published results by a factor of more than 27. These high Q2 data probe the parton structure of the proton at W mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken x value of roughly MW/√{s }=0.16 .
NASA Astrophysics Data System (ADS)
Wang, Xin; Gao, Jun; Fan, Zhiguo; Roberts, Nicholas W.
2016-06-01
We present a computationally inexpensive analytical model for simulating celestial polarization patterns in variable conditions. We combine both the singularity theory of Berry et al (2004 New J. Phys. 6 162) and the intensity model of Perez et al (1993 Sol. Energy 50 235-245) such that our single model describes three key sets of data: (1) the overhead distribution of the degree of polarization as well as the existence of neutral points in the sky; (2) the change in sky polarization as a function of the turbidity of the atmosphere; and (3) sky polarization patterns as a function of wavelength, calculated in this work from the ultra-violet to the near infra-red. To verify the performance of our model we generate accurate reference data using a numerical radiative transfer model and statistical comparisons between these two methods demonstrate no significant difference in almost all situations. The development of our analytical model provides a novel method for efficiently calculating the overhead skylight polarization pattern. This provides a new tool of particular relevance for our understanding of animals that use the celestial polarization pattern as a source of visual information.
Proton Polarization Angular Distribution in Deuteron Photo-Disintegration
Sarty, Adam; Fox, Brendan; Meekins, David; Margaziotis, Demetrius; Kinney, Edward; Garibaldi, Franco; Gao, Juncai; Aniol, Konrad; Epstein, Martin; Amaryan, Moscov; Amaryan, Moskov; Markowitz, Pete; Bosted, Peter; Roche, Rikki; Gilman, Ronald; Frullani, Salvatore; Churchwell, Steve
1999-12-01
The apparent scaling in 90 cm deuteron photodisintegration, first observed several years ago at SLAC, has lead to several related experiments and a number ot theoretical calculations.We have in the past year measured in Hall A, with up to 2.5-GeV photons, cross sections at large angles and the proton polarization at 90cm.Verypreliminary online analysis of the induced polarizations yields the very surprising result that theinduced polarizations apparently vanish starting at about the same energy at whichthe existing cross section data start to scale, to follow the constituent countingrules.Given this result, we propose further measurements to see if this observationholds at other angles.
Polarization recovery and auto-compensation in quantum key distribution network
NASA Astrophysics Data System (ADS)
Ma, Lijun; Xu, Hai; Tang, Xiao
2006-08-01
A Quantum Key Distribution (QKD) network can allow multi-user communication via secure key. Moreover, by actively switching communication nodes, one can achieve high key transmission rate for the selected nodes. However, the polarization properties of different fiber path are different and these properties also randomly drift over time. Therefore, polarization recovery after the switching and auto-compensation during key transmission are critical for the QKD network. In this work, we use programmable polarization controllers to implement polarization recovery and auto-compensation in the QKD network. We will also discuss its time limitation and future improvement.
Gpr125 modulates Dishevelled distribution and planar cell polarity signaling.
Li, Xin; Roszko, Isabelle; Sepich, Diane S; Ni, Mingwei; Hamm, Heidi E; Marlow, Florence L; Solnica-Krezel, Lilianna
2013-07-01
During vertebrate gastrulation, Wnt/planar cell polarity (PCP) signaling orchestrates polarized cell behaviors underlying convergence and extension (C&E) movements to narrow embryonic tissues mediolaterally and lengthen them anteroposteriorly. Here, we have identified Gpr125, an adhesion G protein-coupled receptor, as a novel modulator of the Wnt/PCP signaling system. Excess Gpr125 impaired C&E movements and the underlying cell and molecular polarities. Reduced Gpr125 function exacerbated the C&E and facial branchiomotor neuron (FBMN) migration defects of embryos with reduced Wnt/PCP signaling. At the molecular level, Gpr125 recruited Dishevelled to the cell membrane, a prerequisite for Wnt/PCP activation. Moreover, Gpr125 and Dvl mutually clustered one another to form discrete membrane subdomains, and the Gpr125 intracellular domain directly interacted with Dvl in pull-down assays. Intriguingly, Dvl and Gpr125 were able to recruit a subset of PCP components into membrane subdomains, suggesting that Gpr125 may modulate the composition of Wnt/PCP membrane complexes. Our study reveals a role for Gpr125 in PCP-mediated processes and provides mechanistic insight into Wnt/PCP signaling.
Gpr125 modulates Dishevelled distribution and planar cell polarity signaling
Li, Xin; Roszko, Isabelle; Sepich, Diane S.; Ni, Mingwei; Hamm, Heidi E.; Marlow, Florence L.; Solnica-Krezel, Lilianna
2013-01-01
During vertebrate gastrulation, Wnt/planar cell polarity (PCP) signaling orchestrates polarized cell behaviors underlying convergence and extension (C&E) movements to narrow embryonic tissues mediolaterally and lengthen them anteroposteriorly. Here, we have identified Gpr125, an adhesion G protein-coupled receptor, as a novel modulator of the Wnt/PCP signaling system. Excess Gpr125 impaired C&E movements and the underlying cell and molecular polarities. Reduced Gpr125 function exacerbated the C&E and facial branchiomotor neuron (FBMN) migration defects of embryos with reduced Wnt/PCP signaling. At the molecular level, Gpr125 recruited Dishevelled to the cell membrane, a prerequisite for Wnt/PCP activation. Moreover, Gpr125 and Dvl mutually clustered one another to form discrete membrane subdomains, and the Gpr125 intracellular domain directly interacted with Dvl in pull-down assays. Intriguingly, Dvl and Gpr125 were able to recruit a subset of PCP components into membrane subdomains, suggesting that Gpr125 may modulate the composition of Wnt/PCP membrane complexes. Our study reveals a role for Gpr125 in PCP-mediated processes and provides mechanistic insight into Wnt/PCP signaling. PMID:23821037
Intrinsic transverse momentum and parton correlations from dynamical chiral symmetry breaking
Peter Schweitzer, Mark Strikman, Christian Weiss
2013-01-01
The dynamical breaking of chiral symmetry in QCD is caused by nonperturbative interactions on a distance scale rho ~ 0.3 fm, much smaller than the typical hadronic size R ~ 1 fm. These short-distance interactions influence the intrinsic transverse momentum distributions of partons and their correlations at a low normalization point. We study this phenomenon in an effective description of the low-energy dynamics in terms of chiral constituent quark degrees of freedom, which refers to the large-N_c limit of QCD. The nucleon is obtained as a system of constituent quarks and antiquarks moving in a self-consistent classical chiral field (relativistic mean-field approximation, or chiral quark-soliton model). The calculated transverse momentum distributions of constituent quarks and antiquarks are matched with QCD quarks, antiquarks and gluons at the chiral symmetry--breaking scale rho^{-2}. We find that the transverse momentum distribution of valence quarks is localized at p_T^2 ~ R^{-2} and roughly of Gaussian shape. The distribution of unpolarized sea quarks exhibits a would-be power-like tail ~1/p_T^2 extending up to the chiral symmetry-breaking scale. Similar behavior is observed in the flavor-nonsinglet polarized sea. The high-momentum tails are the result of short-range correlations between sea quarks in the nucleon's light-cone wave function, which are analogous to short-range NN correlations in nuclei. We show that the nucleon's light-cone wave function contains correlated pairs of transverse size rho << R with scalar-isoscalar (Sigma) and pseudoscalar-isovector (Pi) quantum numbers, whose internal wave functions have a distinctive spin structure and become identical at p_T^2 ~ rho^{-2} (restoration of chiral symmetry). These features are model-independent and represent an effect of dynamical chiral symmetry breaking on the nucleon's partonic structure. Our results have numerous implications for the transverse momentum distributions of particles produced in hard
Prompt photon photoproduction at HERA with non-collinear parton dynamics
Lipatov, A. V.; Zotov, N. P.
2011-07-15
We investigate the prompt photon photoproduction at HERA within the framework of the k{sub T}-factorization approach to QCD. Our consideration is based on the off-shell matrix elements for the underlying partonic subprocesses and the Kimber-Martin-Ryskin (KMR) unintegrated parton densities in the proton. We also use the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) unintegrated gluon as well as valence and sea quark distributions.
DETAILED COMPARISON BETWEEN PARTON CASCADE AND HADRONIC CASCADE AT SPS AND RHIC.
NARA,Y.
1998-10-23
The authors study the importance of the partonic phase produced in relativistic heavy ion collision by comparing the parton cascade model and the hadronic cascade model. Hadron yield, baryon stopping and transverse momentum distribution are calculated with JAM and discussions are given comparing with VNI. Both of these models give good description of experimental data. They also discuss the strangeness production mechanism and the directed transverse flow.
NASA Astrophysics Data System (ADS)
Kim, Sang-Hee; Martin, P. G.
1994-08-01
To extract the size distribution of polarizing dust grains from the wavelength dependence of interstellar linear polarization as objectively as possible, we have used the maximum-entropy method (MEM), as in an earlier study of size distributions based on extinction (Kim, Martin, & Hendry). There are additional complications using polarization data since polarization depends on shape and alignment. In this first investigation, we adopted infinite cylinders with perfect spinning alignment. To constrain a wide range of sizes it is necessary to use data from the infrared to the far-ultraviolet. Much of our analysis is based on bare silicate grains. The modified Serkowski law represents interstellar polarization quite well for the wavelength range 0.3 to 2 micrometers using one parameter, lambdamax, the wavelength at which the polarization is maximum. Recent ultraviolet polarimetric observations of eight stars of differing lambdamax indicate that extrapolation of the modified Serkowski curve into the ultraviolet produces a reasonable approximation for larger lambdamax (greater than or approximately 0.55 micrometer), but for smaller lambdamax there is an excess of polarization observed. Therefore, we have investigated how the size distribution of the polarizing grains changes with lambdamax simply by fitting the modified Serkowski curve evaluated for lambdamax = 0.55, 0.615, and 0.68 micrometers. But for HD 25443 (lambdamax = 0.49 micrometer) which shows super-Serkowski behavi or, and for HD 197770 (lambdamax = 0.51 micrometers) which might exhibit a 2175 A polarization bump, we combined the modified Serkowski curve in the infrared and optical with the actual far-ultraviolet data. The size distributions found for silicates bear little resemblance to a power law. Instead, when expressed as contributions to the total mass, they peak roughly at 0.14 micrometer and are skewed, with the relative rate of decrease to larger and smaller sizes depending on lambdamax. For the
QCD constraints on the shape of polarized quark and gluon distributions
NASA Astrophysics Data System (ADS)
Brodsky, Stanley J.; Burkardt, Matthias; Schmidt, Ivan
1995-02-01
We develop simple analytic representations of the polarized quark and gluon distributions in the nucleon at low Q2 which incorporate general constraints obtained from the requirements of color coherence of gluon couplings at x ˜ 0 and the helicity retention properties of perturbative QCD couplings at x ˜ 1. The unpolarized predictions are similar to the Do' distributions given by Martin, Roberts, and Stirling. The predictions for the quark helicity distributions are compared with polarized structure functions measured by the E142 experiment at SLAC and the SMC experiment at CERN.
CARROLL,J.
1999-09-10
The RIKEN-BNL center workshop on ''Hard parton physics in high energy nuclear collisions'' was held at BNL from March 1st-5th! 1999. The focus of the workshop was on hard probes of nucleus-nucleus collisions that will be measured at RHIC with the PHENIX and STAR detectors. There were about 45 speakers and over 70 registered participants at the workshop, with roughly a quarter of the speakers from overseas. About 60% of the talks were theory talks. A nice overview of theory for RHIC was provided by George Sterman. The theoretical talks were on a wide range of topics in QCD which can be classified under the following: (a) energy loss and the Landau-Pomeranchuk-Migdal effect; (b) minijet production and equilibration; (c) small x physics and initial conditions; (d) nuclear parton distributions and shadowing; (e) spin physics; (f) photon, di-lepton, and charm production; and (g) hadronization, and simulations of high pt physics in event generators. Several of the experimental talks discussed the capabilities of the PHENIX and STAR detectors at RHIC in measuring high pt particles in heavy ion collisions. In general, these talks were included in the relevant theory sessions. A session was set aside to discuss the spin program at RHIC with polarized proton beams. In addition, there were speakers from 08, HERA, the fixed target experiments at Fermilab, and the CERN fixed target Pb+Pb program, who provided additional perspective on a range of issues of relevance to RHIC; from jets at the Tevatron, to saturation of parton distributions at HERA, and recent puzzling data on direct photon production in fixed target experiments, among others.
NASA Astrophysics Data System (ADS)
Borka Jovanović, V.; Jovanović, P.; Borka, D.
2017-04-01
We use radio-continuum all-sky surveys at 1420 and 408 MHz with the aim to investigate properties of the Galactic radio source Lupus Loop. The survey data at 1435 MHz, with the linear polarization of the southern sky, are also used. We calculate properties of this supernova remnant: the brightness temperature, surface brightness and radio spectral index. To determine its borders and to calculate its properties, we use the method we have developed. The non-thermal nature of its radiation is confirmed. The distribution of spectral index over its area is also given. A significant correlation between the radio spectral index distribution and the corresponding polarized intensity distribution inside the loop borders is found, indicating that the polarization maps could provide us information about the distribution of the interstellar medium, and thus could represent one additional way to search for new Galactic loops.
NASA Astrophysics Data System (ADS)
Shin, In Hee; Lee, Ji Yong; Lee, Seungrag; Lee, Dong Ju; Kim, Dug Young
2007-02-01
Bio-cells and tissues have intrinsic polarization characteristics, which are changed by external stimulus and internal metamorphosis in cells and tissues and some of the bio-cells and tissues have intrinsic birefringence characteristics, which are also changed by external stimulus and internal metamorphosis in cells and tissues. In this paper, we have developed the polarization microscope for measurement of relative phase which results from birefringence characteristics of materials with improved linear polarizing method and have measured relative phase distribution of onion epidermal cells. From the measurement of the relative phase distribution of onion epidermal cells, decrease of relative phase distribution of onion epidermal cells was investigated as the elapse of time. In decrease of relative phase distribution, relative phase of cell membrane in onion epidermal cells decreased radically as compared with that of cytoplasm because decline of function in cell membrane that takes charge of matter transfer in onion epidermal cells has occurred.
Polarization response of second-harmonic images for different collagen spatial distributions
NASA Astrophysics Data System (ADS)
Ávila, Francisco J.; del Barco, Oscar; Bueno, Juan M.
2016-06-01
The response to polarization of second-harmonic generation (SHG) microscopy images of samples with different collagen distributions (quasialigned, partially organized, and nonorganized) has been analyzed. A linear decay relationship between the external arrangement and polarization sensitivity was found. SHG signal from nonorganized samples presented a large structural dispersion and a weak dependence with incident polarization. Polarization dependence is also associated with the internal organization of the collagen fibers, directly related to the ratio of hyperpolarizabilities ρ. This parameter can experimentally be computed from the modulation of the SHG signal. The results show that both external and internal collagen structures are closely related. This provides a tool to obtain information of internal properties from the polarimetric response of the external spatial distribution of collagen, which might be useful in clinical diagnosis of pathologies related to changes in collagen structure.
Makdisi, Y.
1992-01-01
The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.
Makdisi, Y.
1992-10-01
The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.
Asymmetry distributions and mass effects in dijet events at a polarized HERA
NASA Astrophysics Data System (ADS)
Maul, M.; Schäfer, A.; Mirkes, E.; Rädel, G.
1998-09-01
The asymmetry distributions for several kinematic variables are considered for finding a systematic way to maximize the signal for the extraction of the polarized gluon density. The relevance of mass effects for the corresponding dijet cross section is discussed and the different approximations for including mass effects are compared. We also compare via the programs Pepsi and Mepjet two different Monte Carlo (MC) approaches for simulating the expected signal in the dijet asymmetry at a polarized HERA.
Alim, K; Frey, E
2010-10-01
The dynamic patterning of the plant hormone auxin and its efflux facilitator the PIN protein are the key regulators for the spatial and temporal organization of plant development. In particular auxin induces the polar localization of its own efflux facilitator. Due to this positive feedback, auxin flow is directed and patterns of auxin and PIN arise. During the earliest stage of vein initiation in leaves auxin accumulates in a single cell in a rim of epidermal cells from which it flows into the ground meristem tissue of the leaf blade. There the localized auxin supply yields the successive polarization of PIN distribution along a strand of cells. We model the auxin and PIN dynamics within cells with a minimal canalization model. Solving the model analytically we uncover an excitable polarization front that triggers a polar distribution of PIN proteins in cells. As polarization fronts may extend to opposing directions from their initiation site, we suggest a possible resolution to the puzzling occurrence of bipolar cells, thus we offer an explanation for the development of closed, looped veins. Employing non-linear analysis, we identify the role of the contributing microscopic processes during polarization. Furthermore, we deduce quantitative predictions on polarization fronts establishing a route to determine the up to now largely unknown kinetic rates of auxin and PIN dynamics.
Squark production and decay matched with parton showers at NLO
NASA Astrophysics Data System (ADS)
Gavin, R.; Hangst, C.; Krämer, M.; Mühlleitner, M.; Pellen, M.; Popenda, E.; Spira, M.
2015-01-01
Extending previous work on the predictions for the production of supersymmetric (SUSY) particles at the LHC, we present the fully differential calculation of the next-to-leading order (NLO) SUSY-QCD corrections to the production of squark and squark-antisquark pairs of the first two generations. The NLO cross sections are combined with the subsequent decay of the final state (anti)squarks into the lightest neutralino and (anti)quark at NLO SUSY-QCD. No assumptions on the squark masses are made, and the various subchannels are taken into account independently. In order to obtain realistic predictions for differential distributions the fixed-order calculations have to be combined with parton showers. Making use of the Powheg method we have implemented our results in the Powheg-Box framework and interfaced the NLO calculation with the parton shower Monte Carlo programs Pythia6 and Herwig++. The code is publicly available and can be downloaded from the Powheg-Box webpage. The impact of the NLO corrections on the differential distributions is studied and parton shower effects are investigated for different benchmark scenarios.
NASA Astrophysics Data System (ADS)
Su, Hongxin; Zhao, Ziwei; Feng, Ting; Ding, Dongliang; Li, Zhihong; Yao, X. Steve
2016-11-01
Polarization crosstalk is a phenomenon that the powers of two orthogonal polarization modes propagating in a polarization maintaining (PM) fiber couple into each other. Because there is certain mathematical relationship between the polarization crosstalk signals and external perturbations such as stress and temperature variations, stress and temperature sensing in PM fiber can be simultaneously achieved by measuring the strengths and locations of polarization crosstalk signals. In this paper, we report what we believe the first distributed temperature sensing demonstration using polarization crosstalk analysis in PM fibers. Firstly, by measuring the spacing changes between two crosstalk peaks at different fiber length locations, we obtained the temperature sensing coefficient (TSC) of approximately -0.73 μm/(°C•m), which means that the spacing between two crosstalk peaks induced at two locations changes by 0.73 μm when the temperature changes by 1 °C over a fiber length of 1 meter. Secondly, in order to bring different temperature values at different axial locations along a PM fiber to verify the distributed temperature sensing, four heating-strips are used to heat different fiber sections of the PM fiber under test, and the temperatures measured by the proposed fiber sensing method according to the obtained TSC are almost consistent with those of heating-strips measured by a thermoelectric thermometer. As a new type of distributed fiber temperature sensing technique, we believe that our method will find broad applications in the near future.
Pre-equilibrium parton dynamics: Proceedings
Wang, Xin-Nian
1993-12-31
This report contains papers on the following topics: parton production and evolution; QCD transport theory; interference in the medium; QCD and phase transition; and future heavy ion experiments. This papers have been indexed separately elsewhere on the data base.
Studies of partonic transverse momentum and spin structure of the nucleon
NASA Astrophysics Data System (ADS)
Contalbrigo, M.
2014-06-01
The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. The Thomas Jefferson National Laboratory, after the CEBAF upgrade to 12 GeV, will become the most complete facility for the investigation of the hadron structure in the valence region by scattering of polarized electron off various polarized nucleon targets. A compendium of the planned experiments is here presented.
Radon Transform and Light-Cone Distributions
NASA Astrophysics Data System (ADS)
Teryaev, O. V.
2016-08-01
The relevance of Radon transform for generalized and transverse momentum dependent parton distributions is discussed. The new application for conditional (fracture) parton distributions and dihadron fragmentation functions is suggested.
Multiple parton interaction studies at DØ
Lincoln, D.
2016-04-01
Here, we present the results of studies of multiparton interactions done by the DØ collaboration using the Fermilab Tevatron at a center of mass energy of 1.96 TeV. We also present three analyses, involving three distinct final signatures: (a) a photon with at least 3 jets ( γ + 3jets), (b) a photon with a bottom or charm quark tagged jet and at least 2 other jets ( γ + b/c + 2jets), and (c) two J/ ψ mesons. The fraction of photon + jet events initiated by double parton scattering is about 20%, while the fraction for events inmore » which two J/ ψ mesons were produced is 30 ± 10. While the two measurements are statistically compatible, the difference might indicate differences in the quark and gluon distribution within a nucleon. Finally, this speculation originates from the fact that photon + jet events are created by collisions with quarks in the initial states, while J/ ψ events are produced preferentially by a gluonic initial state.« less
Multiple parton interaction studies at DØ
Lincoln, D.
2016-04-01
Here, we present the results of studies of multiparton interactions done by the DØ collaboration using the Fermilab Tevatron at a center of mass energy of 1.96 TeV. We also present three analyses, involving three distinct final signatures: (a) a photon with at least 3 jets ( γ + 3jets), (b) a photon with a bottom or charm quark tagged jet and at least 2 other jets ( γ + b/c + 2jets), and (c) two J/ ψ mesons. The fraction of photon + jet events initiated by double parton scattering is about 20%, while the fraction for events in which two J/ ψ mesons were produced is 30 ± 10. While the two measurements are statistically compatible, the difference might indicate differences in the quark and gluon distribution within a nucleon. Finally, this speculation originates from the fact that photon + jet events are created by collisions with quarks in the initial states, while J/ ψ events are produced preferentially by a gluonic initial state.
Transverse force on transversely polarized quarks in longitudinally polarized nucleons
NASA Astrophysics Data System (ADS)
Abdallah, Manal; Burkardt, Matthias
2016-11-01
We study the semiclassical interpretation of the x3 and x4 moments of twist-3 parton distribution functions (PDFs). While no semiclassical interpretation for the higher moments of gT(x ) and e (x ) was found, the x3 moment of the chirally odd spin-dependent twist-3 PDF hL3(x ) can be related to the longitudinal gradient of the transverse force on transversely polarized quarks in longitudinally polarized nucleons in a deep-inelastic scattering experiment. We discuss how this result relates to the torque acting on a quark in the same experiment. This has further implications for comparisons between the Jaffe-Manohar and the Ji decompositions of the nucleon spin.
A linear optical protocol of random quantum key distribution by using polarization entangled photons
NASA Astrophysics Data System (ADS)
Cao, Wen-Zhen; Wu, Yan-Hua; Jiang, Hui-Juan; Li, Chong
2010-02-01
Utilized polarization entangled photons, a linear optical protocol for generating random quantum key distribution (QKD) is proposed, which is made up of EPR-source, linear optical elements, and conventional photon detectors. It is shown that total efficiency of QKD η=100% in theory.
Parton shower Monte Carlo event generators
NASA Astrophysics Data System (ADS)
Webber, Bryan
2011-12-01
A parton shower Monte Carlo event generator is a computer program designed to simulate the final states of high-energy collisions in full detail down to the level of individual stable particles. The aim is to generate a large number of simulated collision events, each consisting of a list of final-state particles and their momenta, such that the probability to produce an event with a given list is proportional (approximately) to the probability that the corresponding actual event is produced in the real world. The Monte Carlo method makes use of pseudorandom numbers to simulate the event-to-event fluctuations intrinsic to quantum processes. The simulation normally begins with a hard subprocess, shown as a black blob in Figure 1, in which constituents of the colliding particles interact at a high momentum scale to produce a few outgoing fundamental objects: Standard Model quarks, leptons and/or gauge or Higgs bosons, or hypothetical particles of some new theory. The partons (quarks and gluons) involved, as well as any new particles with colour, radiate virtual gluons, which can themselves emit further gluons or produce quark-antiquark pairs, leading to the formation of parton showers (brown). During parton showering the interaction scale falls and the strong interaction coupling rises, eventually triggering the process of hadronization (yellow), in which the partons are bound into colourless hadrons. On the same scale, the initial-state partons in hadronic collisions are confined in the incoming hadrons. In hadron-hadron collisions, the other constituent partons of the incoming hadrons undergo multiple interactions which produce the underlying event (green). Many of the produced hadrons are unstable, so the final stage of event generation is the simulation of the hadron decays.
Predicting 21st-century polar bear habitat distribution from global climate models
Durner, G.M.; Douglas, D.C.; Nielson, R.M.; Amstrup, Steven C.; McDonald, T.L.; Stirling, I.; Mauritzen, Mette; Born, E.W.; Wiig, O.; Deweaver, E.; Serreze, M.C.; Belikov, Stanislav; Holland, M.M.; Maslanik, J.; Aars, J.; Bailey, D.A.; Derocher, A.E.
2009-01-01
Projections of polar bear (Ursus maritimus) sea ice habitat distribution in the polar basin during the 21st century were developed to understand the consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellitecollared polar bears and environmental data (e.g., bathymetry, distance to coastlines, and sea ice) collected from 1985 to 1995 to build resource selection functions (RSFs). RSFs described habitats that polar bears preferred in summer, autumn, winter, and spring. When applied to independent data from 1996 to 2006, the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st-century sea ice concentration projected by 10 general circulation models (GCMs) used in the Intergovernmental Panel of Climate Change Fourth Assessment Report, under the A1B greenhouse gas forcing scenario. Despite variation in their projections, all GCMs indicated habitat losses in the polar basin during the 21st century. Losses in the highest-valued RSF habitat (optimal habitat) were greatest in the southern seas of the polar basin, especially the Chukchi and Barents seas, and least along the Arctic Ocean shores of Banks Island to northern Greenland. Mean loss of optimal polar bear habitat was greatest during summer; from an observed 1.0 million km2 in 1985-1995 (baseline) to a projected multi-model mean of 0.32 million km2 in 2090-2099 (-68% change). Projected winter losses of polar bear habitat were less: from 1.7 million km2 in 1985-1995 to 1.4 million km2 in 2090-2099 (-17% change). Habitat losses based on GCM multi-model means may be conservative; simulated rates of habitat loss during 1985-2006 from many GCMs were less than the actual observed rates of loss. Although a reduction in the total amount of optimal habitat will likely reduce polar bear populations, exact relationships between habitat losses and population demographics remain unknown. Density and energetic
NASA Astrophysics Data System (ADS)
Day, Donal; Keller, Dustin; Zhang, Jixie
2016-09-01
Wide angle compton scattering from polarized protons holds great promise: access to the generalized parton distribution functions H and E with different weighting and moments than in other hard exclusive processes, emphasizing the u-quarks and the valence region. Previously, experiments were proposed using bremsstrahlung from polarized electrons striking a radiator. Unfortunately the mixed electron- γ beam limits the polarized target performance due to radiation damage and restricted luminosity owing to the heat load. We have designed a pure photon beam line by placing a dipole magnet after the radiator which deflects the electrons away from the target and into a beam dump. This approach has many benefits which include an order of magnitude increase in the photon luminosity and unrestricted use of transversely polarized targets while preserving robust target performance. We will discuss the physics motivation, the design (of two different options) as well as the G4beamline simulation results of the source.
NASA Astrophysics Data System (ADS)
Ntarlagiannis, D.; Ustra, A.; Slater, L. D.; Zhang, C.; Mendonça, C. A.
2015-12-01
In this work we present an alternative formulation of the Debye Decomposition (DD) of complex conductivity spectra, with a new set of parameters that are directly related to the continuous Debye relaxation model. The procedure determines the relaxation time distribution (RTD) and two frequency-independent parameters that modulate the induced polarization spectra. The distribution of relaxation times quantifies the contribution of each distinct relaxation process, which can in turn be associated with specific polarization processes and characterized in terms of electrochemical and interfacial parameters as derived from mechanistic models. Synthetic tests show that the procedure can successfully fit spectral induced polarization (SIP) data and accurately recover the RTD. The procedure was applied to different data sets, focusing on environmental applications. We focus on data of sand-clay mixtures artificially contaminated with toluene, and crude oil-contaminated sands experiencing biodegradation. The results identify characteristic relaxation times that can be associated with distinct polarization processes resulting from either the contaminant itself or transformations associated with biodegradation. The inversion results provide information regarding the relative strength and dominant relaxation time of these polarization processes.
The distribution of polarized radio sources >15 μJy IN GOODS-N
Rudnick, L.; Owen, F. N.
2014-04-10
We present deep Very Large Array observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.''6 and 10''. At 1.''6, we find that the peak flux cumulative number count distribution is N(> p) ∼ 45*(p/30 μJy){sup –0.6} per square degree above a detection threshold of 14.5 μJy. This represents a break from the steeper slopes at higher flux densities, resulting in fewer sources predicted for future surveys with the Square Kilometer Array and its precursors. It provides a significant challenge for using background rotation measures (RMs) to study clusters of galaxies or individual galaxies. Most of the polarized sources are well above our detection limit, and they are also radio galaxies that are well-resolved even at 10'', with redshifts from ∼0.2-1.9. We determined a total polarized flux for each source by integrating the 10'' polarized intensity maps, as will be done by upcoming surveys such as POSSUM. These total polarized fluxes are a factor of two higher, on average, than the peak polarized flux at 1.''6; this would increase the number counts by ∼50% at a fixed flux level. The detected sources have RMs with a characteristic rms scatter of ∼11 rad m{sup –2} around the local Galactic value, after eliminating likely outliers. The median fractional polarization from all total intensity sources does not continue the trend of increasing at lower flux densities, as seen for stronger sources. The changes in the polarization characteristics seen at these low fluxes likely represent the increasing dominance of star-forming galaxies.
Bell, Marcus G; Dale, Robert E; van der Heide, Uulke A; Goldman, Yale E
2002-01-01
The method of polarized fluorescence depletion (PFD) has been applied to enhance the resolution of orientational distributions and dynamics obtained from fluorescence polarization (FP) experiments on ordered systems, particularly in muscle fibers. Previous FP data from single fluorescent probes were limited to the 2(nd)- and 4(th)-rank order parameters,
and
, of the probe angular distribution (beta) relative to the fiber axis and
, a coefficient describing the extent of rapid probe motions. We applied intense 12-micros polarized photoselection pulses to transiently populate the triplet state of rhodamine probes and measured the polarization of the ground-state depletion using a weak interrogation beam. PFD provides dynamic information describing the extent of motions on the time scale between the fluorescence lifetime (e.g., 4 ns) and the duration of the photoselection pulse and it potentially supplies information about the probe angular distribution corresponding to order parameters above rank 4. Gizzard myosin regulatory light chain (RLC) was labeled with the 6-isomer of iodoacetamidotetramethylrhodamine and exchanged into rabbit psoas muscle fibers. In active contraction, dynamic motions of the RLC on the PFD time scale were intermediate between those observed in relaxation and rigor. The results indicate that previously observed disorder of the light chain region in contraction can be ascribed principally to dynamic motions on the microsecond time scale. PMID:12124286
Polarization-basis tracking scheme for quantum key distribution using revealed sifted key bits.
Ding, Yu-Yang; Chen, Wei; Chen, Hua; Wang, Chao; Li, Ya-Ping; Wang, Shuang; Yin, Zhen-Qiang; Guo, Guang-Can; Han, Zheng-Fu
2017-03-15
The calibration of the polarization basis between the transmitter and receiver is an important task in quantum key distribution. A continuously working polarization-basis tracking scheme (PBTS) will effectively promote the efficiency of the system and reduce the potential security risk when switching between the transmission and calibration modes. Here, we proposed a single-photon level continuously working PBTS using only sifted key bits revealed during an error correction procedure, without introducing additional reference light or interrupting the transmission of quantum signals. We applied the scheme to a polarization-encoding BB84 QKD system in a 50 km fiber channel, and obtained an average quantum bit error rate (QBER) of 2.32% and a standard derivation of 0.87% during 24 h of continuous operation. The stable and relatively low QBER validates the effectiveness of the scheme.
Davies, Alexander; Formstone, Caroline; Mason, Ivor; Lewis, Julian
2005-07-01
Hair cells of the vertebrate inner ear are directional mechanosensors: they have a polarity, defined by a vector in the plane of the sensory epithelium. It has been suggested that this polarity might be controlled by genes homologous to those that control planar cell polarity (PCP) in Drosophila, and vertebrate homologues of the Drosophila PCP genes Van Gogh/strabismus and flamingo/starry night are indeed essential for normal hair cell PCP. The underlying molecular mechanism is unclear, however. Although the PCP protein Flamingo shows a polarized intracellular distribution in the fly, it is unknown whether this is necessary for its function. Here, we describe the expression pattern of a flamingo homologue, c-flamingo-1 (c-fmi-1), in the developing chick ear and show that its protein product, like that of flamingo in the fly, has a polarized distribution in each hair cell, defining an axis that corresponds to the structural PCP axis. This conservation between fly and vertebrate suggests that the polarized protein localization is functionally important. In the basilar papilla, the same localization is seen in supporting cells also, suggesting that supporting cells are cryptically polarized, despite having no overt structural polarity; they may thus participate in PCP signal transmission across the sensory patch.
APFELgrid : A high performance tool for parton density determinations
NASA Astrophysics Data System (ADS)
Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P.
2017-03-01
We present a new software package designed to reduce the computational burden of hadron collider measurements in Parton Distribution Function (PDF) fits. The APFELgrid package converts interpolated weight tables provided by APPLgrid files into a more efficient format for PDF fitting by the combination with PDF and αs evolution factors provided by APFEL. This combination significantly reduces the number of operations required to perform the calculation of hadronic observables in PDF fits and simplifies the structure of the calculation into a readily optimised scalar product. We demonstrate that our technique can lead to a substantial speed improvement when compared to existing methods without any reduction in numerical accuracy.
Parton Propagation and Fragmentation in QCD Matter
Alberto Accardi, Francois Arleo, William Brooks, David D'Enterria, Valeria Muccifora
2009-12-01
We review recent progress in the study of parton propagation, interaction and fragmentation in both cold and hot strongly interacting matter. Experimental highlights on high-energy hadron production in deep inelastic lepton-nucleus scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan processes in hadron-nucleus collisions are presented. The existing theoretical frameworks for describing the in-medium interaction of energetic partons and the space-time evolution of their fragmentation into hadrons are discussed and confronted to experimental data. We conclude with a list of theoretical and experimental open issues, and a brief description of future relevant experiments and facilities.
Evolution of parton fragmentation functions at finitetemperature
Osborne, Jonathan; Wang, Enke; Wang, Xin-Nian
2002-06-12
The first order correction to the parton fragmentation functions in a thermal medium is derived in the leading logarithmic approximation in the framework of thermal field theory. The medium-modified evolution equations of the parton fragmentation functions are also derived. It is shown that all infrared divergences, both linear and logarithmic, in the real processes are canceled among themselves and by corresponding virtual corrections. The evolution of the quark number and the energy loss (or gain) induced by the thermal medium are investigated.
LaRue, Michelle A.; Stapleton, Seth P.; Porter, Claire; Atkinson, Stephen N.; Atwood, Todd C.; Dyck, Markus; Lecomte, Nicolas
2015-01-01
High-resolution satellite imagery is a promising tool for providing coarse information about polar species abundance and distribution, but current applications are limited. With polar bears (Ursus maritimus), the technique has only proven effective on landscapes with little topographic relief that are devoid of snow and ice, and time-consuming manual review of imagery is required to identify bears. Here, we evaluated mechanisms to further develop methods for satellite imagery by examining data from Rowley Island, Canada. We attempted to automate and expedite detection via a supervised spectral classification and image differencing to expedite image review. We also assessed what proportion of a region should be sampled to obtain reliable estimates of density and abundance. Although the spectral signature of polar bears differed from nontarget objects, these differences were insufficient to yield useful results via a supervised classification process. Conversely, automated image differencing—or subtracting one image from another—correctly identified nearly 90% of polar bear locations. This technique, however, also yielded false positives, suggesting that manual review will still be required to confirm polar bear locations. On Rowley Island, bear distribution approximated a Poisson distribution across a range of plot sizes, and resampling suggests that sampling >50% of the site facilitates reliable estimation of density (CV <15%). Satellite imagery may be an effective monitoring tool in certain areas, but large-scale applications remain limited because of the challenges in automation and the limited environments in which the method can be effectively applied. Improvements in resolution may expand opportunities for its future uses.
NASA Technical Reports Server (NTRS)
Mishchenko, M. I.; Travis, L. D.
1993-01-01
Calculations of light scattering by small particles are important in many diverse fields of science and engineering. In many cases of practical interest, scattering particles are nonspherical and are distributed over sizes and orientations. However, accurate light scattering computations for ensembles of nonspherical particles are difficult and time-consuming, and the literature in which such calculations are reported is rather scarce. In this paper, the T-matrix approach, as extended recently to randomly oriented particles, is used to calculate rigorously light scattering by size distributions of randomly oriented axially symmetric particles. To model the variation of particle sizes in real ensembles, we use a power law distribution typical of some terrestrial aerosols. Contour plots of intensity and degree of linear polarization for polydisperse prolate and oblate spheroids of different aspect ratios and effective equivalent-sphere size parameters from 0 to 10 are calculated and compared with calculations for equivalent spheres. The angular scattering behavior of nonspherical polydispersions is found to be greatly different from that of spheres, while the scattering properties of oblate and prolate spheroids of the same aspect ratio are similar. With increasing particle size, both intensity and polarization become more shape-dependent. In general, nonspherical particles are stronger side scatterers and weaker backscatterers than equivalent spheres. With increasing aspect ratio of nonspherical particles polarization tends to be predominantly positive. Possible effects of particle nonsphericity on optical remote sensing of atmospheric aerosols are discussed.
Fragmentation of parton jets at small x
Kirschner, R.
1985-08-01
The parton fragmentation function is calculated in the region of small x in the doubly logarithmic approximation of QCD. For this, the method of separating the softest particle, which has hitherto been applied only in the Regge kinematic region, is developed. Simple arguments based on unitarity and gauge invariance are used to derive the well known condition of ordering of the emission angles.
QCD parton model at collider energies
Ellis, R.K.
1984-09-01
Using the example of vector boson production, the application of the QCD improved parton model at collider energies is reviewed. The reliability of the extrapolation to SSC energies is assessed. Predictions at ..sqrt..S = 0.54 TeV are compared with data. 21 references.
Systematic Improvement of QCD Parton Showers
Winter, Jan; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna; Schumann, Steffen; Siegert, Frank; /Freiburg U.
2012-05-17
In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.
Investigating GPDs in the framework of the double distribution model
NASA Astrophysics Data System (ADS)
Nazari, F.; Mirjalili, A.
2016-06-01
In this paper, we construct the generalized parton distribution (GPD) in terms of the kinematical variables x, ξ, t, using the double distribution model. By employing these functions, we could extract some quantities which makes it possible to gain a three-dimensional insight into the nucleon structure function at the parton level. The main objective of GPDs is to combine and generalize the concepts of ordinary parton distributions and form factors. They also provide an exclusive framework to describe the nucleons in terms of quarks and gluons. Here, we first calculate, in the Double Distribution model, the GPD based on the usual parton distributions arising from the GRV and CTEQ phenomenological models. Obtaining quarks and gluons angular momenta from the GPD, we would be able to calculate the scattering observables which are related to spin asymmetries of the produced quarkonium. These quantities are represented by AN and ALS. We also calculate the Pauli and Dirac form factors in deeply virtual Compton scattering. Finally, in order to compare our results with the existing experimental data, we use the difference of the polarized cross-section for an initial longitudinal leptonic beam and unpolarized target particles (ΔσLU). In all cases, our obtained results are in good agreement with the available experimental data.
Nachtmann, O.
2014-11-15
We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell–Yan process and soft photon production in hadron–hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell–Yan reaction. Also for Higgs-boson production in pp collisions via gluon–gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell–Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.
Non-dipolar Wilson Links for Parton Densities
NASA Astrophysics Data System (ADS)
Li, Hsiang-nan
We propose a new definition of a transverse-momentum-dependent wave function with simpler soft subtraction. The unsubtracted wave function involves two pieces of non-light-like Wilson links oriented in different directions, so that the rapidity singularity appearing in usual kT factorization is regularized, and the pinched singularity from Wilson-link self-energy corrections is alleviated to a logarithmic one. We show explicitly at one-loop level that the simpler definition with the non-dipolar Wilson links exhibits the same infrared behavior as the one with the dipolar Wilson links. The non-dipolar Wilson links are also introduced to the quasi-parton distribution function (QPDF) with an equal-time correlator in the large momentum limit, which can remove the involved linear divergence, and allow perturbative matching to the standard light-cone parton distribution function. The latter can then be extracted reliably from Euclidean lattice data for the QPDF with the non-dipolar Wilson links.
An O({alpha}{sub s}) Monte Carlo for W production with parton showering
Baer, H.A.
1991-12-31
We construct an event generator for p{bar p}{yields}W{sup +}X{yields}e{sup +}{nu}X including complete O({alpha}{sub s}) corrections, and interface with initial and final state parton showers. Problems with negative weights and with double counting higher order parton radiation are averted. We present results for W+n-jet production, and compare with results from complete tree-level calculations, and shower calculations off of the lowest order 2{yields}2 sub-process. We also compute the {sub qT}(W) distribution, and compare with data.
An O([alpha][sub s]) Monte Carlo for W production with parton showering
Baer, H.A.
1991-01-01
We construct an event generator for p[bar p][yields]W[sup +]X[yields]e[sup +][nu]X including complete O([alpha][sub s]) corrections, and interface with initial and final state parton showers. Problems with negative weights and with double counting higher order parton radiation are averted. We present results for W+n-jet production, and compare with results from complete tree-level calculations, and shower calculations off of the lowest order 2[yields]2 sub-process. We also compute the [sub qT](W) distribution, and compare with data.
Zhang, Shukui; Poelker, Matthew; Stutzman, Marcy L.; Chen, Yiqiao; Moy, Aaron
2015-09-01
Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.
NASA Astrophysics Data System (ADS)
Kley, D.; Smit, H. G. J.; Duhnke, K.
The region of the polar jet stream plays an important role in exchange processes be- tween stratosphere and troposphere. In a statistical study ozone and water vapor mea- surements obtained from the MOZAIC (=Measurement of Ozone and Water Vapor by Airbus In Service Aircraft) project were used to investigate atmospheric dynamics in the region of the polar jet over the North-Atlantic. From a one year record of more than 1000 transatlantic MOZAIC-flights cross- sectional distributions of ozone and relative humidity inside the polar jet stream are composed and analyzed. A synoptical approach is employed, using daily weather anal- ysis maps of the European Centre for Medium Range Weather Forecast, to develop a coordinate transformation method which enables to position MOZAIC water vapor and ozone data relative to the jet-axis. Inside the jet the cross sections of ozone and humidity show a local circulation pattern across the tropopause with an indication of a net downward flux which is most pro- nounced in spring and has a minimum in autumn. The paper will discuss the observed circulation pattern inside the polar jet in terms of transport across the tropopause and its implications on the budget of ozone and water vapor in the UT/LS-region.
2016-06-02
is derived to facilitate use of secondary polarization. The model is supported by exper- imental MFOV lidar measurements carried out in a controlled ...Retrieval of droplet-size density distribution from multiple-field-of- view cross-polarized lidar signals: theory and experimental validation...Gilles Roy, Luc Bissonnette, Christian Bastille, and Gilles Vallee Multiple-field-of- view (MFOV) secondary-polarization lidar signals are used to
Effects produced by multi-parton interactions and color reconnection in small systems
NASA Astrophysics Data System (ADS)
Cuautle, Eleazar; Ortiz, Antonio; Paić, Guy
2016-12-01
Multi-parton interactions and color reconnection can produce QGP-like effects in small systems, specifically, radial flow-like patterns. For pp collisions simulated with Pythia 8.212, in this work we investigate their effects on different observables like event multiplicity, event shapes and transverse momentum distributions.
NASA Astrophysics Data System (ADS)
Tang, Zhiyuan; Liao, Zhongfa; Xu, Feihu; Qi, Bing; Qian, Li; Lo, Hoi-Kwong
2014-05-01
We demonstrate the first implementation of polarization encoding measurement-device-independent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks. Active phase randomization of each individual pulse is implemented to protect against attacks on imperfect sources. By optimizing the parameters in the decoy state protocol, we show that it is feasible to implement polarization encoding MDI-QKD with commercial off-the-shelf devices. A rigorous finite key analysis is applied to estimate the secure key rate. Our work paves the way for the realization of a MDI-QKD network, in which the users only need compact and low-cost state-preparation devices and can share complicated and expensive detectors provided by an untrusted network server.
NASA Astrophysics Data System (ADS)
Gao, Cheng-Yan; Wang, Guan-Yu; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo
2017-03-01
Hyperentanglement is a significant resource for high-capacity quantum communication. Here we present a robust spatial-polarization hyperentanglement distribution scheme for two-photon systems. The error on the polarization states of two-photon systems transmitted from two paths can be corrected resorting to the robust time-bin entanglement which suffers little from the channel noise. The spatial bit-flip error takes place with a very small probability and the spatial phase-flip error can be precluded by adjusting the path-length of spatial modes. Using this scheme, the two parties in quantum communication can share a maximally hyperentangled state of two-photon systems in a deterministic way, which will improve the efficiency of quantum communication largely.
NASA Astrophysics Data System (ADS)
Freda, W.; Piskozub, J.; Toczek, H.
2015-12-01
This article describes a method for determining the angular distribution of light polarization over a roughened surface of the sea. Our method relies on measurements of the Stokes vector elements using a polarization imaging camera that operates using the Division of Focal Plane (DoFP) method. It uses special monochrome CCD array in which the neighbouring cells, instead of recording different colours (red green and blue), are equipped with micropolarizers of four directions (0, 45, 90 and 135 degrees). We combined the camera with a fish-eye lens of Field of View (FoV) > 180 deg. Such a large FoV allowed us to crop out the fragment of the frame along the circular horizon, showing a view covering all directions of the hemisphere. Because of complicated optical design of the fish-eye lens (light refraction on surfaces of parts of the lens) connected to the sensor we checked the accuracy of the measurement system. A method to determine the accuracy of measured polarization is based on comparison of the experimentally obtained rotation matrix with its theoretical form. Such a comparison showed that the maximum error of Stokes vector elements depended on zenith angle and reached as much as 24% for light coming from just above the horizon, but decreased rapidly with decreasing zenith angle to the value of 12% for the angles 10Â° off the edge of FoV. Moreover we present the preliminary results prepared over rough sea surface. These results include total intensity of light, Degree of Linear Polarization (DoLP) and their standard deviations. The results have been averaged over one thousand frames of a movie. These results indicate that the maximum polarization is observed near the reflection of the sun, and the signal coming from below the surface may be observed at zenith angles far from the vertical direction.
Interannual variability of monthly sea-ice distributions in the north polar region
Parkinson, C.L.
1992-03-01
Passive-microwave data from the Nimbus 5 and Nimbus 7 satellites have been used to determine and map, by month, the interannual variability of the spatial distribution of north polar sea ice over the period 1973-1987. Results are illustrated for the months of January and July, during the winter ice growth and summer ice decay seasons, respectively. In January, the greatest interannual variability in the distribution of the ice occurs in the Sea of Okhotsk, whereas the portions of the ice edge exhibiting the least interannual variability lie in the southern Greenland Sea and immediately to the southwest of Svalbard. In July, spatial variability is high in Hudson Bay, Baffin Bay, the southern Kara Sea, and the northern Barents Sea. The monthly maps are meant to allow ready comparison with past and future sea ice distributions and aid in the assessment of whether specific changes are climatically important.
The influence of subsurface flow on lake formation and north polar lake distribution on Titan
NASA Astrophysics Data System (ADS)
Horvath, David G.; Andrews-Hanna, Jeffrey C.; Newman, Claire E.; Mitchell, Karl L.; Stiles, Bryan W.
2016-10-01
Observations of lakes, fluvial dissection of the surface, rapid variations in cloud cover, and lake shoreline changes indicate that Saturn's moon Titan is hydrologically active, with a hydrocarbon-based hydrological cycle dominated by liquid methane. Here we use a numerical model to investigate the Titan hydrological cycle - including surface, subsurface, and atmospheric components - in order to investigate the underlying causes of the observed distribution and sizes of lakes in the north polar region. The hydrocarbon-based hydrological cycle is modeled using a numerical subsurface flow model and analytical runoff scheme, driven by a general circulation model with an active methane-cycle. This model is run on synthetically generated topography that matches the fractal character of the observed topography, without explicit representation of the effects of erosion and deposition. At the scale of individual basins, intermediate to high permeability (10-8-10-6 cm2) aquifers are required to reproduce the observed large stable lakes. However, at the scale of the entire north polar lake district, a high permeability aquifer results in the rapid flushing of methane through the aquifer from high polar latitudes to dry lower polar latitudes, where methane is removed by evaporation, preventing large lakes from forming. In contrast, an intermediate permeability aquifer slows the subsurface flow from high polar latitudes, allowing greater lake areas. The observed distribution of lakes is best matched by either a uniform intermediate permeability aquifer, or a combination of a high permeability cap at high latitudes surrounded by an intermediate permeability aquifer at lower latitudes, as could arise due to karstic processes at the north pole. The stability of Kraken Mare further requires reduction of the evaporation rate over the sea to 1% of the value predicted by the general circulation model, likely as a result of dissolved ethane, nitrogen, or organic solutes, and/or a
NASA Technical Reports Server (NTRS)
Hairston, Marc R.; Heelis, Roderick A.; Rich, Frederick J.
1995-01-01
During the time from December 1991 through March 1992, there were four operational DMSP satellites in polar orbit. All four satellites carried the Special Sensor-Ions, Electrons, Scintillation (SSIES) plasma package which included an ion drift meter. Data from the drift meter, combined with the magnetic field data, allowed the calculation of the electrostatic potential in the ionosphere along the satellite's path. Simultaneous polar coverage by four satellites was unprecedented, providing researchers with almost continuous monitoring of the potential distribution in both hemispheres for the four month period. Combining the magnitude and location of the potential data from each of the four satellites in order to examine the varying potential distribution pattern in both hemispheres presented a major challenge in data visualization. The problem was solved by developing a three-dimensional presentation of the data where the potentials are color coded and represented by the vertical dimension. This paper presents examples from a computer animation of several days of data demonstrating evolution of the size and shape of the potential distribution, along with how these changes correspond to variations in other geophysical parameters, such as the IMF orientation and the K(sub p) index.
Pulsar magnetospheres, braking index, polar caps, and period-pulse-width distribution.
NASA Technical Reports Server (NTRS)
Roberts, D. H.; Sturrock, P. A.
1973-01-01
An investigation is conducted concerning the trapping of gas and its effect on the structure of the magnetic field. The aligned and orthogonal cases are discussed in detail. In each case, there are small collection zones which are both microscopically and macroscopically stable. By determining where macroscopic stability changes to instability, the separatrix between closed and open field lines is investigated together with the sizes and shapes of the polar caps. This information makes it possible to reexamine the period-pulse-width distribution and to compare it with observational data.
Galimov, A.A.; Glazov, N.P.; Ivanov, V.T.
1985-08-01
The protection of metallic structures from corrosion is effected by cathodic polarization and protective coatings. At sites of damage extending through the insulation an intense corrosion process, which causes the formation of corrosion pits, in which signifiant redistribution of the protective current occurs, takes place. Considered in this paper is the distribution of the current on an electrode with a corrosion pit of arbitrary shape in the example of an electrochemical system consisting of disk electrodes located in a cylindrical bath with a lateral insulator surface. The overall analysis of the numerical results points out the significant redistribution of the current on a protected metallic surface when corrosion pits appear.
Cilia distribution and polarity in the epithelial lining of the mouse middle ear cavity
Luo, Wenwei; Yi, Hong; Taylor, Jeannette; Li, Jian-dong; Chi, Fanglu; Todd, N. Wendell; Lin, Xi; Ren, Dongdong; Chen, Ping
2017-01-01
The middle ear conducts sound to the cochlea for hearing. Otitis media (OM) is the most common illness in childhood. Moreover, chronic OM with effusion (COME) is the leading cause of conductive hearing loss. Clinically, COME is highly associated with Primary Ciliary Dyskinesia, implicating significant contributions of cilia dysfunction to COME. The understanding of middle ear cilia properties that are critical to OM susceptibility, however, is limited. Here, we confirmed the presence of a ciliated region near the Eustachian tube orifice at the ventral region of the middle ear cavity, consisting mostly of a lumen layer of multi-ciliated and a layer of Keratin-5-positive basal cells. We also found that the motile cilia are polarized coordinately and display a planar cell polarity. Surprisingly, we also found a region of multi-ciliated cells that line the posterior dorsal pole of the middle ear cavity which was previously thought to contain only non-ciliated cells. Our study provided a more complete understanding of cilia distribution and revealed for the first time coordinated polarity of cilia in the epithelium of the mammalian middle ear, thus illustrating novel structural features that are likely critical for middle ear functions and related to OM susceptibility. PMID:28358397
QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING.
SHIMIZU, H.; STERMAN, G.; VOGELSANG, W.; YOKOYA, H.
2005-10-02
We present a recent study of the QCD corrections to dilepton production near partonic threshold in transversely polarized {bar p}p scattering, We analyze the role of the higher-order perturbative QCD corrections in terms of the available fixed-order contributions as well as of all-order soft-gluon resummations for the kinematical regime of proposed experiments at GSI-FAIR. We find that perturbative corrections are large for both unpolarized and polarized cross sections, but that the spin asymmetries are stable. The role of the far infrared region of the momentum integral in the resummed exponent and the effect of the NNLL resummation are briefly discussed.
NASA Technical Reports Server (NTRS)
Comiso, Joey C.
1995-01-01
Surface temperature is one of the key variables associated with weather and climate. Accurate measurements of surface air temperatures are routinely made in meteorological stations around the world. Also, satellite data have been used to produce synoptic global temperature distributions. However, not much attention has been paid on temperature distributions in the polar regions. In the polar regions, the number of stations is very sparse. Because of adverse weather conditions and general inaccessibility, surface field measurements are also limited. Furthermore, accurate retrievals from satellite data in the region have been difficult to make because of persistent cloudiness and ambiguities in the discrimination of clouds from snow or ice. Surface temperature observations are required in the polar regions for air-sea-ice interaction studies, especially in the calculation of heat, salinity, and humidity fluxes. They are also useful in identifying areas of melt or meltponding within the sea ice pack and the ice sheets and in the calculation of emissivities of these surfaces. Moreover, the polar regions are unique in that they are the sites of temperature extremes, the location of which is difficult to identify without a global monitoring system. Furthermore, the regions may provide an early signal to a potential climate change because such signal is expected to be amplified in the region due to feedback effects. In cloud free areas, the thermal channels from infrared systems provide surface temperatures at relatively good accuracies. Previous capabilities include the use of the Temperature Humidity Infrared Radiometer (THIR) onboard the Nimbus-7 satellite which was launched in 1978. Current capabilities include the use of the Advance Very High Resolution Radiometer (AVHRR) aboard NOAA satellites. Together, these two systems cover a span of 16 years of thermal infrared data. Techniques for retrieving surface temperatures with these sensors in the polar regions have
Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS
Silvia Niccolai
2012-04-01
This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH{sub 3}) and deuterons (ND{sub 3}) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.
Why do sand furrow distributions vary in the North Polar latitudes on Mars?
NASA Astrophysics Data System (ADS)
Bourke, Mary; McGaley-Towle, Zoe
2014-05-01
Sand dunes on Mars display geomorphic evidence of an active and dynamic sediment flux. Barchan dunes migrate, ripples move and the slipface morphology changes annually. Aeolian sediment transport is seasonally constrained and linked to cryogenic processes. Sand furrows are geomorphic features that are eroded into the surface of dunes. They form during sublimation of the seasonal carbon dioxide deposit which moves gas and sand through vents in the ice (cryo-venting) (Bourke, 2013). They are visible on the surface of dunes using the highest resolution images available for Mars. Previous work has noted that the distribution of furrows varies spatially both on individual dunes and at different Polar locations. Here we report on the preliminary findings of a mapping project that seeks to confirm this previous qualitative observation. In addition, we aim to explain the observed spatial and temporal variation in sand furrows on North Polar dunes. Ten polar sites that reflect a latitudinal range of 9.5º are being analysed. The HiRISE images were acquired between 16/2/2012 and 31/05/2012, over a period of 105 Earth days or 102 Sols. We have completed mapping of 1711 sand furrows in an 84 km2 area of sand dunes, i.e. at four of the ten sites. The data confirm that there is variability in the distribution of sand furrows in the Polar Region. While data from all ten sites will be required to fully test the assertion of a latitudinal control, it is worth noting that the two most northerly sites have a significantly higher density of furrows compared to the two lower latitude sites. As the seasonal ice thickness is known to increases pole-ward on Mars, our data suggest that effective furrow formation may be linked to ice deposit thickness. In particular, it suggests that a threshold in ice thickness must be crossed in order for effective cryo-venting to occur. Bourke, M.C., 2013. Sand Furrows: A new surface feature on Martian dunes, EGU, EGU2013-11859, Vienna.
NASA Astrophysics Data System (ADS)
Estévez, Irene; Lizana, Angel; Zheng, Xuejie; Peinado, Alba; Ramírez, Claudio; Martínez, Jose Luis; Márquez, Andrés.; Moreno, Ignacio; Campos, Juan
2015-06-01
Liquid Crystals on Silicon (LCOS) displays are a type of LCDs that work in reflection. Such devices, due to the double pass that the light beam performs through the LC cells, lead to larger phase modulation than transmissive LCDs with the same thickness. By taking advantage of this modulation capability exhibited by LCOS displays, we propose a new experimental set-up which is able to provide customized state of polarization spatial distributions just by means of a single LCOS display. To this aim, a double reflection on different halves of the display is properly performed. This fact is achieved by including a compact optical system that steers the light and performs a proper polarization plane rotation. The set-up has been experimentally implemented and some experimental concerns are discussed. The suitability of the system is provided by generating different experimental spatial distributions of polarization. In this regard, well-known polarization distributions, as axial, azimuthal or spiral linear polarization patterns are here provided. Based on the excellent results obtained, the suitability of the system to generate different spatially variant distributions of polarization is validated.
Adamczyk, L.
2015-08-26
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, ALL, in polarized pp collisions at center-of-mass energy √s = 200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. Lastly, the measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x > 0.05 .
Adamczyk, L.
2015-08-26
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, A_{LL}, in polarized pp collisions at center-of-mass energy √s = 200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. Lastly, the measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x > 0.05 .
NASA Astrophysics Data System (ADS)
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cudd, A. B.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration
2015-08-01
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, AL L, in polarized p p collisions at center-of-mass energy √{s }=200 GeV . The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC p p data. The measured asymmetries provide evidence at the 3 σ level for positive gluon polarization in the Bjorken-x region x >0.05 .
Theoretical estimate on tensor-polarization asymmetry in proton-deuteron Drell-Yan process
NASA Astrophysics Data System (ADS)
Kumano, S.; Song, Qin-Tao
2016-09-01
Tensor-polarized parton distribution functions are new quantities in spin-1 hadrons such as the deuteron, and they could probe new quark-gluon dynamics in hadron and nuclear physics. In charged-lepton deep inelastic scattering, they are studied by the twist-2 structure functions b1 and b2. The HERMES Collaboration found unexpectedly large b1 values compared to a naive theoretical expectation based on the standard deuteron model. The situation should be significantly improved in the near future by an approved experiment to measure b1 at Thomas Jefferson National Accelerator Facility (JLab). There is also an interesting indication in the HERMES result that finite antiquark tensor polarization exists. It could play an important role in solving a mechanism on tensor structure in the quark-gluon level. The tensor-polarized antiquark distributions are not easily determined from the charged-lepton deep inelastic scattering; however, they can be measured in a proton-deuteron Drell-Yan process with a tensor-polarized deuteron target. In this article, we estimate the tensor-polarization asymmetry for a possible Fermilab Main-Injector experiment by using optimum tensor-polarized parton distribution functions to explain the HERMES measurement. We find that the asymmetry is typically a few percent. If it is measured, it could probe new hadron physics, and such studies could create an interesting field of high-energy spin physics. In addition, we find that a significant tensor-polarized gluon distribution should exist due to Q2 evolution, even if it were zero at a low Q2 scale. The tensor-polarized gluon distribution has never been observed, so it is an interesting future project.
Large-momentum distribution of a polarized Fermi gas and p -wave contacts
NASA Astrophysics Data System (ADS)
Peng, Shi-Guo; Liu, Xia-Ji; Hu, Hui
2016-12-01
We present a derivation of the adiabatic energy relations as well as the large momentum distribution of a polarized Fermi gas near p -wave Feshbach resonances. The leading asymptotic behavior k-2 and subleading behavior k-4 of the large momentum distribution have recently been predicted by Z. Yu et al. [Phys. Rev. Lett. 115, 135304 (2015), 10.1103/PhysRevLett.115.135304] and by M. Y. He et al. [Phys. Rev. Lett. 116, 045301 (2016), 10.1103/PhysRevLett.116.045301] using two different approaches. Here, we show that the subleading asymptotic behavior (˜k-4 ) cannot fully be captured by the contact defined from the adiabatic energy relation related to the p -wave effective range, and there should be an extra term resulting from the center-of-mass motion of the pairs. The omission of this extra term is perhaps a reasonable approximation at zero temperature. However, it should be taken into account at finite temperature and should have significant importance to understand the recently measured momentum distribution in a resonant p -wave Fermi gas of ultracold 40K atoms [C. Luciuk et al., Nat. Phys. 12, 599 (2016), 10.1038/nphys3670].
Polarization in the land distribution, land use and land cover change in the Amazon
D'ANTONA, Alvaro; VANWEY, Leah; LUDEWIGS, Thomas
2013-01-01
The objective of this article is to present Polarization of Agrarian Structure as a single, more complete representation than models emphasizing rural exodus and consolidation of land into large agropastoral enterprises of the dynamics of changing land distribution, land use / cover, and thus the rural milieu of Amazonia. Data were collected in 2003 using social surveys on a sample of 587 lots randomly selected from among 5,086 lots on a cadastral map produced in the 1970s. Georeferencing of current property boundaries in the location of these previously demarcated lots allows us to relate sociodemographic and biophysical variables of the surveyed properties to the changes in boundaries that have occurred since the 1970s. As have other authors in other Amazonian regions, we found concentration of land ownership into larger properties. The approach we took, however, showed that changes in the distribution of land ownership is not limited to the appearance of larger properties, those with 200 ha or more; there also exists substantial division of earlier lots into properties with fewer than five hectares, many without any agropastoral use. These two trends are juxtaposed against the decline in establishments with between five and 200 ha. The variation across groups in land use / land cover and population distribution shows the necessity of developing conceptual models, whether from socioeconomic, demographic or environmental perspectives, look beyond a single group of people or properties. PMID:24639597
Simulation of particle size distributions in Polar Mesospheric Clouds from Microphysical Models
NASA Astrophysics Data System (ADS)
Thomas, G. E.; Merkel, A.; Bardeen, C.; Rusch, D. W.; Lumpe, J. D.
2009-12-01
The size distribution of ice particles is perhaps the most important observable aspect of microphysical processes in Polar Mesospheric Cloud (PMC) formation and evolution. A conventional technique to derive such information is from optical observation of scattering, either passive solar scattering from photometric or spectrometric techniques, or active backscattering by lidar. We present simulated size distributions from two state-of-the-art models using CARMA sectional microphysics: WACCM/CARMA, in which CARMA is interactively coupled with WACCM3 (Bardeen et al, 2009), and stand-alone CARMA forced by WACCM3 meteorology (Merkel et al, this meeting). Both models provide well-resolved size distributions of ice particles as a function of height, location and time for realistic high-latitude summertime conditions. In this paper we present calculations of the UV scattered brightness at multiple scattering angles as viewed by the AIM Cloud Imaging and Particle Size (CIPS) satellite experiment. These simulations are then considered discretely-sampled “data” for the scattering phase function, which are inverted using a technique (Lumpe et al, this meeting) to retrieve particle size information. We employ a T-matrix scattering code which applies to a wide range of non-sphericity of the ice particles, using the conventional idealized prolate/oblate spheroidal shape. This end-to-end test of the relatively new scattering phase function technique provides insight into both the retrieval accuracy and the information content in passive remote sensing of PMC.
The Distribution of Ozone in the Early Stages of Polar Vortex Development
NASA Technical Reports Server (NTRS)
Kawa, S. R.; Newman, P. A.; Schoeberl, M. R.; Bevilacqua, R.; Bhartia, P. K. (Technical Monitor)
2002-01-01
Previous analysis has shown that the distribution of O3 at high northern latitudes in the lower-to-middle stratosphere at the beginning of the winter season, 1999-2000 has a characteristic distribution, which is consistent between in situ and satellite measurements [Kawa et al., The Interaction Between Dynamics and Chemistry of Ozone in the Set-up Phase of the Northern Hemisphere Polar Vortex, submitted manuscript, 2001 ]. Initial O3 profiles in the vortex are similar to each other and are quite different from outside the vortex at the same latitude and also from a zonal mean climatology. In the vortex, O3 is nearly constant from 500 to above 800 K with a value at 3 ppmv +/- approx.10%. Values outside the vortex are up to a factor of 2 higher and increase significantly with potential temperature. The seasonal time series of POAM data shows that relatively low O3 mixing ratios, which characterize the vortex in late fall, are already present at high latitudes at the end of summer in September before the vortex circulation sets up. This suggests a possible feedback role between O3 chemistry and the formation of the vortex, which is dominated by the seasonal radiation balance. Here we show that these characteristic O3 distributions are consistent from year to year and between the hemispheres. We will attempt to determine whether variations in fall vortex O3 are related in any way to O3 abundances and vortex structure later during winter and into spring.
Zhang, D.S.; Wei, G.W.; Kouri, D.J. ); Hoffman, D.K. ); Gorman, M.; Palacios, A. ); Gunaratne, G.H. The Institute of Fundamental Studies, Kandy )
1999-09-01
An algorithm is presented to integrate nonlinear partial differential equations, which is particularly useful when accurate estimation of spatial derivatives is required. It is based on an analytic approximation method, referred to as distributed approximating functionals (DAF[close quote]s), which can be used to estimate a function and a finite number of derivatives with a specified accuracy. As an application, the Kuramoto-Sivashinsky (KS) equation is integrated in polar coordinates. Its integration requires accurate estimation of spatial derivatives, particularly close to the origin. Several stationary and nonstationary solutions of the KS equation are presented, and compared with analogous states observed in the combustion front of a circular burner. A two-ring, nonuniform counter-rotating state has been obtained in a KS model simulation of such a burner. [copyright] [ital 1999] [ital The American Physical Society
Implementation of polarization-coded free-space BB84 quantum key distribution
NASA Astrophysics Data System (ADS)
Kim, Y.-S.; Jeong, Y.-C.; Kim, Y.-H.
2008-06-01
We report on the implementation of a Bennett-Brassard 1984 quantum key distribution protocol over a free-space optical path on an optical table. Attenuated laser pulses and Pockels cells driven by a pseudorandom number generator are employed to prepare polarization-encoded photons. The sifted key generation rate of 23.6 kbits per second and the quantum bit error rate (QBER) of 3% have been demonstrated at the average photon number per pulse μ = 0.16. This QBER is sufficiently low to extract final secret keys from shared sifted keys via error correction and privacy amplification. We also tested the long-distance capability of our system by adding optical losses to the quantum channel and found that the QBER remains the same regardless of the loss.
NASA Astrophysics Data System (ADS)
Bradley, C. L.; Kupinski, M.; Xu, F.; Diner, D. J.; Chipman, R. A.
2015-12-01
Remote sensing algorithms for aerosol retrieval rely on surface reflectance models for the extraction of path radiance of aerosol scattering in top of atmosphere measurements. A well-defined surface boundary condition is necessary due to the variability in the surface albedo and bidirectional reflectance distribution function. Polarization measurements can help constrain the surface model. Prior work features polarization measurements taken by Jet Propulsion Laboratory's Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI). This work has shown that an analytical model that assumes singly reflected light from a rough surface comprised of microfacets sufficiently represents the polarized reflectance of natural surfaces (such as grass), but is less successful for manmade objects. For the linear Stokes parameters (I, Q, U), a single reflection of unpolarized light will result in a null U Stokes parameter relative to the scattering plane. However, some GroundMSPI measurements exhibit a non-zero U Stokes parameter. We show that multiple reflections may be a cause for this discrepancy by using a polarization ray trace (PRT) routine to calculate the polarized Bidirectional Reflectance Distribution Function (pBRDF) for a microfaceted surface. While the effect of multiple reflections, particularly for double reflections, is an order of magnitude smaller compared to single reflections, we show non-zero U Stokes parameters generated from multiple reflections. Furthermore, we have found that for illumination-view geometries with scattering angles less than ~45 degrees, Q and U parameters can have similar magnitude. We report on the magnitude of this effect and compare the PRT simulations to non-zero U measurements from GroundMSPI.
Excited nucleon as a van der Waals system of partons
Jenkovszky, L. L.; Muskeyev, A. O. Yezhov, S. N.
2012-06-15
Saturation in deep inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) is associated with a phase transition between the partonic gas, typical of moderate x and Q{sup 2}, and partonic fluid appearing at increasing Q{sup 2} and decreasing Bjorken x. We suggest the van der Waals equation of state to describe properly this phase transition.
Alexandru, Andrei; Draper, Terrence; Horvath, Ivan; Streuer, Thomas
2011-08-15
Highlights: > We propose a method to compute the polarization for a multi-dimensional random distribution. > We apply the method to the eigenemodes of the Dirac operator in pure glue QCD. > We compute the chiral polarization for these modes and study its scale dependence. > We find that in a finite volume there is a scale where the polarization tendency changes. > We study the continuum limit of this chiral polarization scale. - Abstract: We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left-right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of 'low' and 'high' Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD.
Dynamics of hot and dense nuclear and partonic matter
Bratkovskaya, E. L.; Cassing, W.; Linnyk, O.; Konchakovski, V. P.; Voronyuk, V.; Ozvenchuk, V.
2012-06-15
The dynamics of hot and dense nuclear matter is discussed from the microscopic transport point of view. The basic concepts of the Hadron-String-Dynamical transport model (HSD)-derived from Kadanoff-Baym equations in phase phase-are presented as well as 'highlights' of HSD results for different observables in heavy-ion collisions from 100 A MeV (SIS) to 21 A TeV(RHIC) energies. Furthermore, a novel extension of the HSD model for the description of the partonic phase-the Parton-Hadron-String-Dynamics (PHSD) approach-is introduced. PHSD includes a nontrivial partonic equation of state-in line with lattice QCD-as well as covariant transition rates from partonic to hadronic degrees of freedom. The sensitivity of hadronic observables to the partonic phase is demonstrated for relativistic heavy-ion collisions from the FAIR/NICA up to the RHIC energy regime.
Polarized 3He target and Final State Interactions in SiDIS
Del Dotto, Alessio; Kaptari, Leonid; Pace, Emanuele; ...
2017-01-03
Jefferson Lab is starting a wide experimental program aimed at studying the neutron’s structure, with a great emphasis on the extraction of the parton transverse-momentum distributions (TMDs). To this end, Semi-inclusive deep-inelastic scattering (SiDIS) experiments on polarized $^3$He will be carried out, providing, together with proton and deuteron data, a sound flavor decomposition of the TMDs. Here, given the expected high statistical accuracy, it is crucial to disentangle nuclear and partonic degrees of freedom to get an accurate theoretical description of both initial and final states. In this contribution, a preliminary study of the Final State Interaction (FSI) in themore » standard SiDIS, where a pion (or a Kaon) is detected in the final state is presented, in view of constructing a realistic description of the nuclear initial and final states.« less
Polarized ^{\\varvec{3}}He Target and Final State Interactions in SiDIS
NASA Astrophysics Data System (ADS)
Del Dotto, Alessio; Kaptari, Leonid; Pace, Emanuele; Salmè, Giovanni; Scopetta, Sergio
2017-01-01
Jefferson Lab is starting a wide experimental program aimed at studying the neutron's structure, with a great emphasis on the extraction of the parton transverse-momentum distributions (TMDs). To this end, Semi-inclusive deep-inelastic scattering (SiDIS) experiments on polarized ^3He will be carried out, providing, together with proton and deuteron data, a sound flavor decomposition of the TMDs. Given the expected high statistical accuracy, it is crucial to disentangle nuclear and partonic degrees of freedom to get an accurate theoretical description of both initial and final states. In this contribution, a preliminary study of the Final State Interaction (FSI) in the standard SiDIS, where a pion (or a Kaon) is detected in the final state is presented, in view of constructing a realistic description of the nuclear initial and final states.
NASA Astrophysics Data System (ADS)
Yuan, Kai-Jun; Chelkowski, Szczepan; Bandrauk, André D.
2016-05-01
We theoretically investigate molecular photoelectron momentum distributions (MPMDs) by bichromatic [frequencies (ω1,ω2)] circularly polarized attosecond UV laser pulses. Simulations performed on aligned single-electron H2+ by numerically solving the corresponding three-dimensional time-dependent Schrödinger equation within a static nucleus frame show that MPMDs exhibit a spiral structure for both co-rotating and counter-rotating schemes. Results are analyzed by attosecond perturbation ionization models. Coherent electron wave packets created, respectively, by the two color pulses in the continuum interfere with each other. Photoionization distributions are functions of the photoelectron momentum p and the ejection angle θ , thus leading to spiral MPMDs. The dependence of spiral MPMDs on the time delay between the bicircular pulses and their relative phases is also presented. The spiral interference patterns are determined by the helicities and frequencies (ω1,ω2 ) of the bicircular fields. It is also found that the spiral patterns are sensitive to the molecular alignment and suppressed by two-center ionization interference, thus offering new tools for imaging molecular geometry.
Terazulene Isomers: Polarity Change of OFETs through Molecular Orbital Distribution Contrast.
Yamaguchi, Yuji; Takubo, Maki; Ogawa, Keisuke; Nakayama, Ken-Ichi; Koganezawa, Tomoyuki; Katagiri, Hiroshi
2016-09-07
Intermolecular orbital coupling is fundamentally important to organic semiconductor performance. Recently, we reported that 2,6':2',6″-terazulene (TAz1) exhibited excellent performance as an n-type organic field-effect transistor (OFET) via molecular orbital distribution control. To validate and develop this concept, here we present three other terazulene regioisomers, which have three azulene molecules connected at the 2- or 6-position along the long axis of the azulene, thus constructing a linear expanded π-conjugation system: 2,2':6',2″-terazulene (TAz2), 2,2':6',6″-terazulene (TAz3), and 6,2':6',6″-terazulene (TAz4). TAz2 and TAz3 exhibit ambipolar characteristics; TAz4 exhibits clear n-type transistor behavior as an OFET. The lowest unoccupied molecular orbitals (LUMOs) of all terazulenes are fully delocalized over the entire molecule. In contrast, the highest occupied molecular orbitals (HOMOs) of TAz2 and TAz3 are delocalized over the 2,2'-biazulene units; the HOMOs of TAz4 are localized at one end of the azulene unit. These findings confirm that terazulene isomers which are simple hydrocarbon compounds are versatile materials with a tunable-polarity FET characteristic that depends on the direction of the azulene unit and the related contrast of the molecular orbital distribution in the terazulene backbone.
Hussain, S.; Marchand, R.
2014-07-15
We discuss sheath and kinetic effects on ion and electron distribution functions at the aperture of enhanced Polar Outflow Probe particle sensors. For this purpose, the interaction between the CASSIOPE spacecraft and space environment is simulated fully kinetically using the electrostatic Particle In Cell code PTetra. The simulations account for the geometry of the main features of the spacecraft body, the booms, and the sensors. In addition to the background plasma, the model also accounts for Earth magnetic field. The plasma parameters assumed in the simulations are obtained from the latest version of the International Reference Ionosphere (IRI) model and the value of magnetic field is obtained from the International Geophysical Reference Field model. Our analysis shows significant distortions in the ion distribution function in the plane of the sensor aperture, as well as in the direction along the boom holding the sensor. We argue that significant distortions and asymmetries should also occur at the aperture of the suprathermal electron imager when suprathermal electrons are detected, with energies of 5 eV or more.
NASA Technical Reports Server (NTRS)
Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.
2004-01-01
The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).
Barco-Bonilla, Nieves; Romero-González, Roberto; Plaza-Bolaños, Patricia; Garrido Frenich, Antonia; Martínez Vidal, José Luis
2010-12-10
The analysis of a wide range of pesticides in wastewaters (WWs) undergoing different treatments (both modern and conventional) has been studied. The need for optimizing specific extraction methods for each WW effluent based on their physico-chemical characteristics has been considered. A distribution study was performed to establish if the filtration step before extraction is a correct procedure since pesticides can be more prone to be in the aqueous or the solid phase, depending on their hydrophobicity. This evaluation demonstrated that pesticides are distributed between the aqueous phase and the suspended particulate matter (SPM; e.g. pyrethroids are only found in the SPM). The proposed methodologies involved the determination of 39 polar and 139 non-polar pesticides using solid-phase extraction (SPE) and pressurized-liquid extraction (PLE) for the extraction of the aqueous phase and the SPM, respectively. Ultra high pressure liquid chromatography and gas chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS, GC-MS/MS) were used in the determination stage. WW samples from four different technologies were evaluated: membrane bioreactor, extended aeration, maturation pond and anaerobic pond. Validation data for the four effluents studied were generated, obtaining adequate precision values (estimated as % relative standard deviation, RSD) in almost all cases (<25%). The methods showed limits of detection at 0.01-0.20μgL(-1) and limits of quantification from 0.02 to 0.50μgL(-1). The proposed methods were applied to the analysis of real samples collected from an experimental WW treatment plant, detecting non-polar and polar pesticides at concentrations in the range 0.02-1.94μgL(-1) and 0.02-0.33μgL(-1), respectively.
Adare, A.
2016-03-23
In this article, we present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from W±/Z decays, produced in longitudinally polarized p+p collisions at center of mass energies of √s=500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the W-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb-1, which exceeds previous PHENIX published results by a factor of more than 27.more » In addition, these high Q2 data probe the parton structure of the proton at W mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken x value of roughly MW/√s=0.16.« less
Zhou, Rihong; Guo, Zhen; Watson, Charles; Chen, Emily; Kong, Rong; Wang, Wenxian; Yao, Xuebiao
2003-01-01
Actin cytoskeleton plays an important role in the establishment of epithelial cell polarity. Cdc42, a member of Rho GTPase family, modulates actin dynamics via its regulators, such as IQGAP proteins. Gastric parietal cells are polarized epithelial cells in which regulated acid secretion occurs in the apical membrane upon stimulation. We have previously shown that actin isoforms are polarized to different membrane domains and that the integrity of the actin cytoskeleton is essential for acid secretion. Herein, we show that Cdc42 is preferentially distributed to the apical membrane of gastric parietal cells. In addition, we revealed that two Cdc42 regulators, IQGAP1 and IQGAP2, are present in gastric parietal cells. Interestingly, IQGAP2 is polarized to the apical membrane of the parietal cells, whereas IQGAP1 is mainly distributed to the basolateral membrane. An IQGAP peptide that competes with full-length IQGAP proteins for Cdc42-binding in vitro also inhibits acid secretion in streptolysin-O-permeabilized gastric glands. Furthermore, this peptide disrupts the association of IQGAP and Cdc42 with the apical actin cytoskeleton and prevents the apical membrane remodeling upon stimulation. We propose that IQGAP2 forms a link that associates Cdc42 with the apical cytoskeleton and thus allows for activation of polarized secretion in gastric parietal cells. PMID:12631726
A model for autumn pelagic distribution of adult female polar bears in the Chukchi Seas, 1987-1994
Durner, G.M.; Douglas, D.C.; Nielson, R.M.; Amstrup, Steven C.
2006-01-01
We made predictions of polar bear (Ursus maritimus) autumn distribution in the Chukchi Sea with a Resource Selection Function (RSF) developed from 1198 satellite radio-collar locations on 124 adult female polar bears, 1987 – 1994. The RSF was created to assist in an aerial survey design for polar bears proposed by the U.S. Fish and Wildlife Service. The RSF was based on bathymetry and daily sea ice covariates extracted from passive microwave satellite imagery within the pelagic region > 25 km from shore. The RSF indicated that polar bears selected habitats with intermediate amounts (~50%) of ice cover in close proximity to higher ice concentrations, and over relatively shallow waters. The RSF showed good predictive abilities for the years of its construct, worked best in October, and was robust to inter-annual variability. When evaluated with recent (1997 – 2005) data, the RSF performed well for October and November but poorly in September. This loss of predictive abilities appeared to be related to recent changes in habitat due to longer melt seasons and younger sea ice, and testing the retrospective model with a small sample of recent polar bears locations from a limited region of the Chukchi Sea. Contemporary applications of this RSF must consider three factors that could limit its utility: 1) 2 different sea ice phenology; 2) distributions of males and sub-adults; and 3) occupancy in nearshore habitats.
A polarized neutron study of the magnetization distribution in Co₂FeSi.
Brown, P J; Kainuma, R; Kanomata, T; Neumann, K-U; Okubo, A; Umetsu, R Y; Ziebeck, K R A
2013-05-22
The magnetization distribution in Co2FeSi which has the largest moment per formula unit ∼6 μB of all Heusler alloys, has been determined using polarized neutron diffraction. The experimentally determined magnetization has been integrated over spheres centred on the three sites of the L12 structure giving μ Fe = 3.10(3) μB and μ Co = 1.43(2) μB, results which are slightly lower than the moments in atomic spheres of similar radii obtained in recent LDA + U band structure calculations (Li et al 2010 Chin. Phys. B 19 097102). Approximately 50% of the magnetic carriers at the Fe sites were found to be in orbitals with eg symmetry. This was higher, ≃65%, at the Co sites. Both Fe and Co were found to have orbital moments that are larger than those predicted. Comparison with similar results obtained for related alloys suggests that there must be a finite density of states in both spin bands at the Fermi energy indicating that Co2FeSi is not a perfect half-metallic ferromagnet.
Estimating Fiber Orientation Distribution Functions in 3D-Polarized Light Imaging
Axer, Markus; Strohmer, Sven; Gräßel, David; Bücker, Oliver; Dohmen, Melanie; Reckfort, Julia; Zilles, Karl; Amunts, Katrin
2016-01-01
Research of the human brain connectome requires multiscale approaches derived from independent imaging methods ideally applied to the same object. Hence, comprehensible strategies for data integration across modalities and across scales are essential. We have successfully established a concept to bridge the spatial scales from microscopic fiber orientation measurements based on 3D-Polarized Light Imaging (3D-PLI) to meso- or macroscopic dimensions. By creating orientation distribution functions (pliODFs) from high-resolution vector data via series expansion with spherical harmonics utilizing high performance computing and supercomputing technologies, data fusion with Diffusion Magnetic Resonance Imaging has become feasible, even for a large-scale dataset such as the human brain. Validation of our approach was done effectively by means of two types of datasets that were transferred from fiber orientation maps into pliODFs: simulated 3D-PLI data showing artificial, but clearly defined fiber patterns and real 3D-PLI data derived from sections through the human brain and the brain of a hooded seal. PMID:27147981
Double parton scattering in pair production of J /ψ mesons at the LHC revisited
NASA Astrophysics Data System (ADS)
Borschensky, Christoph; Kulesza, Anna
2017-02-01
Double parton scattering (DPS) is studied for the example of J /ψ pair production in the LHCb and ATLAS experiments of the Large Hadron Collider (LHC) at center-of-mass energies of √{S }=7 , 8, and 13 TeV. We report theoretical predictions delivered to the LHCb and ATLAS Collaborations adjusted for the fiducial volumes of the corresponding measurements during run I, and we provide new predictions at 13 TeV collision energy. It is shown that DPS can lead to noticeable contributions in the distributions of longitudinal variables of the di-J /ψ system, especially at 13 TeV. The increased DPS rate in double J /ψ production at high energies will open up more possibilities for the separation of single parton scattering and DPS contributions in future studies.
NASA Astrophysics Data System (ADS)
Becker, Maik; Bredemeyer, Niels; Tenhumberg, Nils; Turek, Thomas
2016-03-01
Potential probes are applied to vanadium redox-flow batteries for determination of effective felt resistance and current density distribution. During the measurement of polarization curves in 100 cm2 cells with different carbon felt compression rates, alternating potential steps at cell voltages between 0.6 V and 2.0 V are applied. Polarization curves are recorded at different flow rates and states of charge of the battery. Increasing compression rates lead to lower effective felt resistances and a more uniform resistance distribution. Low flow rates at high or low state of charge result in non-linear current density distribution with high gradients, while high flow rates give rise to a nearly linear behavior.
Collins, John; Rogers, Ted
2015-04-01
There is considerable controversy about the size and importance of non-perturbative contributions to the evolution of transverse momentum dependent (TMD) parton distribution functions. Standard fits to relatively high-energy Drell-Yan data give evolution that when taken to lower Q is too rapid to be consistent with recent data in semi-inclusive deeply inelastic scattering. Some authors provide very different forms for TMD evolution, even arguing that non-perturbative contributions at large transverse distance bT are not needed or are irrelevant. Here, we systematically analyze the issues, both perturbative and non-perturbative. We make a motivated proposal for the parameterization of the non-perturbative part ofmore » the TMD evolution kernel that could give consistency: with the variety of apparently conflicting data, with theoretical perturbative calculations where they are applicable, and with general theoretical non-perturbative constraints on correlation functions at large distances. We propose and use a scheme- and scale-independent function A(bT) that gives a tool to compare and diagnose different proposals for TMD evolution. We also advocate for phenomenological studies of A(bT) as a probe of TMD evolution. The results are important generally for applications of TMD factorization. In particular, they are important to making predictions for proposed polarized Drell- Yan experiments to measure the Sivers function.« less
Collins, John; Rogers, Ted
2015-04-01
There is considerable controversy about the size and importance of non-perturbative contributions to the evolution of transverse momentum dependent (TMD) parton distribution functions. Standard fits to relatively high-energy Drell-Yan data give evolution that when taken to lower Q is too rapid to be consistent with recent data in semi-inclusive deeply inelastic scattering. Some authors provide very different forms for TMD evolution, even arguing that non-perturbative contributions at large transverse distance bT are not needed or are irrelevant. Here, we systematically analyze the issues, both perturbative and non-perturbative. We make a motivated proposal for the parameterization of the non-perturbative part of the TMD evolution kernel that could give consistency: with the variety of apparently conflicting data, with theoretical perturbative calculations where they are applicable, and with general theoretical non-perturbative constraints on correlation functions at large distances. We propose and use a scheme- and scale-independent function A(bT) that gives a tool to compare and diagnose different proposals for TMD evolution. We also advocate for phenomenological studies of A(bT) as a probe of TMD evolution. The results are important generally for applications of TMD factorization. In particular, they are important to making predictions for proposed polarized Drell- Yan experiments to measure the Sivers function.
Hierarchical model of fibrillar collagen distribution for polarization-resolved SHG microscopy
NASA Astrophysics Data System (ADS)
Tuer, Adam E.; Akens, Margarete K.; Krouglov, Serguei; Sandkuijl, Daaf; Wilson, Brian C.; Whyne, Cari M.; Barzda, Virginijus
2013-02-01
A hierarchical model of the organization of fibrillar collagen is developed and its implications on polarization-resolved second harmonic generation (SHG) microscopy are investigated. A "ground-up" approach is employed to develop the theory for understanding of the origin of SHG from fibrillar collagen. The effects of fibril ultrastructure and fibril macroscopic organization on the second-order polarization properties of fibrillar collagen are presented in conjunction with recent ab initio results performed on a collagen triple-helix model (-GLY-PRO-HYP-)n. Various tissues containing fibrillar collagen are quantified using a polarization-resolved SHG technique, termed polarization-in, polarization-out (PIPO) and interpreted in light of the aforementioned theory. The method involves varying the incident laser polarization, while monitoring the SHG intensity through an analyzer. From the SHG polarization data the orientation of the fibers, in biological tissue, can be deduced. Unique PIPO signatures are observed for different rat tissues and interpreted in terms of the collagen composition, fibril ultrastructure, and macroscopic organization. Similarities and discrepancies in the second-order polarization properties of different collagen types and ultrastructures will be presented. PIPO SHG microscopy shows promise in its ability to quantify the organization of collagen in various tissues. The ability to characterize the structure of collagen in various tissue microenvironments will aid in the study of numerous collagen related biological process, including tissue diseases, wound repair, and tumor development and progression.
Ardavan, Houshang; Ardavan, Arzhang; Singleton, John
2003-11-01
We investigate the spectral features of the emission from a superluminal polarization current whose distribution pattern rotates (with an angular frequency omega) and oscillates (with a frequency omega > omega differing from an integral multiple of omega) at the same time. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. Although all of the processes involved are linear, we find that the broadband emission contains frequencies that are higher than omega by a factor of the order of (omega/omega)2. This generation of frequencies not required for the creation of the source stems from mathematically rigorous consequences of the familiar classical expression for the retarded potential. The results suggest practical applications for superluminal polarization currents as broadband radio-frequency and infrared sources.
NASA Technical Reports Server (NTRS)
Conrad, A. H.; Stephens, A. P.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)
1994-01-01
Some effects of gravity on early morphogenesis are correlated with microtubule locations within cells. During first cleavage in Ilyanassa obsoleta embryos, a transitory polar lobe constriction forms and then relaxes, allowing the polar lobe to merge with one daughter cell. If the polar lobe is equally divided or removed, morphogenesis is severely disrupted. To examine microtuble locations during early Ilyanassa development, eggs were fixed and stained for polymerized alpha-tubulin during first cleavage. The mitotic apparatus assembles at the animal pole. The cleavage furrow forms between the asters, constricting to a stabilized intercellular bridge encircling midbody-bound microtubules, whereas the polar lobe constriction forms below and parallel to the spindle, constricting to a transitory intercellular bridge encircling no detectable microtubules. At metaphase an alpha-tubulin epitope is distributed throughout the spindle, whereas a beta-tubulin epitope is present predominantly in the asters. Incubation in hexylene glycol, a drug that increases microtubule polymerization, during mitosis causes the polar lobe constriction to tighten around polymerized alpha-tubulin and remain stably constricted. If hexylene glycol is removed, alpha-tubulin staining disappears from the polar lobe constriction, which relaxes, whereas microtubules remain in the cleavage furrow, which remains constricted. These observations suggest that asymmetric distribution of microtubules affects early Ilyanassa cleavage patterns, and that continued presence of microtubules extending through an intercellular bridge is important for stabilization of the bridge constriction prior to completion of cytokinesis. These data provide the basis for further analysis of the role of microtubules in possible microgravity disruptions of Ilyanassa development.
NASA Astrophysics Data System (ADS)
Lee, Jae-Ok; Moon, Y.-J.; Lee, Jin-Yi; Lee, Kyoung-Sun; Kim, R.-S.
2016-04-01
We determine coronal electron density distributions (CEDDs) by analyzing decahectometric (DH) type II observations under two assumptions. DH type II bursts are generated by either (1) shocks at the leading edges of coronal mass ejections (CMEs) or (2) CME shock-streamer interactions. Among 399 Wind/WAVES type II bursts (from 1997 to 2012) associated with SOHO/LASCO (Large Angle Spectroscopic COronagraph) CMEs, we select 11 limb events whose fundamental and second harmonic emission lanes are well identified. We determine the lowest frequencies of fundamental emission lanes and the heights of leading edges of their associated CMEs. We also determine the heights of CME shock-streamer interaction regions. The CEDDs are estimated by minimizing the root-mean-square error between the heights from the CME leading edges (or CME shock-streamer interaction regions) and DH type II bursts. We also estimate CEDDs of seven events using polarized brightness (pB) measurements. We find the following results. Under the first assumption, the average of estimated CEDDs from 3 to 20 Rs is about 5-fold Saito's model (NSaito(r)). Under the second assumption, the average of estimated CEDDs from 3 to 10 Rs is 1.5-fold NSaito(r). While the CEDDs obtained from pB measurements are significantly smaller than those based on the first assumption and CME flank regions without streamers, they are well consistent with those on the second assumption. Our results show that not only about 1-fold NSaito(r) is a proper CEDD for analyzing DH type II bursts but also CME shock-streamer interactions could be a plausible origin for generating DH type II bursts.
NASA Astrophysics Data System (ADS)
Kourtchev, Ivan
Terrestrial vegetation releases substantial amounts of reactive volatile organic compounds (VOCs; e.g., isoprene, monoterpenes) into the atmosphere. The VOCs can be rapidly photooxidized under conditions of high solar radiation, yielding products that can participate in new particle formation and growth processes above forests. This thesis focuses on the characterization, identification and quantification of oxidation products of biogenic VOC (BVOCs) as well as other species (tracer compounds) that provide information on aerosol sources and source processes. Atmospheric aerosols from various forested sites (i.e., Hyytiala, southern Finland; Rondonia, Brazil; K-Puszta, Hungary and Julich, Germany) were analyzed with Gas Chromotography/Mass Spectrometry (GC/MS) using analytical procedure that targets polar organic compounds. The study demonstrated that isoprene (i.e., 2-methyerythritol, 2-methylthreitol, 2-methylglyceric acid and C5-alkene triols (2-methyl-1,3,4-trihydroxy-l-butene (cis and trans) and 3 methyl-2,3,4-trihydroxy-1-butene)) and monoterpene (pinic acid, norpinic acid, 3-hydroxyglutaric acid and 3-methyl-1,2,3-butanetricarboxylic acid) oxidation products were present in substantial concentrations in atmospheric aerosols suggesting that oxidation of BVOC from the vegetation is an important process in all studied sites. On the other hand, presence of levoglucosan, biomass burning marker, especially in Amazonian rain forest site at Rondonia, Brazil, pointed that all sites were affected by anthropogenic activities, namely biomass burning. Other identified compounds included plyols, arabitol, mannitol and erythritol, which are marker compounds for fungal spores and monosacharides, glucose and fructose, markers for plant polens. Temporal variations as well as mass size distributions of the detected species confirmed the possible formation mechanisms of marker compounds.
Gerchikov, L.G.; Aulenbacher, K.; Clendenin, J.E.; Kuz'michev, V.V.; Mamaev, Yu.A.; Maruyama, T.; Mikhrin, V.S.; Roberts, J.S.; Utstinov, V.M.; Vasiliev, D.A.; Vasiliev, A.P.; Yashin, Yu.P.; Zhukov, A.E.; /St. Petersburg Polytechnic Inst. /Mainz U., Inst. Kernphys. /SLAC /Ioffe Phys. Tech. Inst. /Sheffield U.
2007-11-28
Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these photocathodes for spin-polarized electron sources.
Gerchikov, L. G.; Kuz'michev, V. V.; Mamaev, Yu. A.; Vasiliev, D. A.; Yashin, Yu. P.; Aulenbacher, K.; Clendenin, J. E.; Maruyama, T.; Mikhrin, V. S.; Ustinov, V. M.; Vasiliev, A. P.; Zhukov, A. E.; Roberts, J. S.
2008-02-06
Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these photocathodes for spin-polarized electron sources.
Nonlinear dust acoustic waves with polarization force effects in Kappa distribution plasma
NASA Astrophysics Data System (ADS)
Chen, Hui; Zhou, Suyun; Luo, Rongxiang; Liu, Sanqiu
2017-01-01
The propagation characteristics of dust acoustic solitary waves (DASWs) in dusty plasmas with the effects of polarization force and superthermal ions are studied. First, the polarization force induced by superthermal ions is obtained. It is shown that the superthermality of background ions affect the Debye screening of dust grains as well as the polarization force significantly. Then for small amplitude solitary waves, the KdV equation is obtained by applying the reductive perturbation technique. And for the arbitrary amplitude solitary waves, the Sagdeev potential method is employed and the Sagdeev potential is analyzed. In both case, the effects of the polarization force associated the ions’ superthermality on the characteristic of the DASWs are analyzed.
Backward dilepton production in color dipole and parton models
Gay Ducati, Maria Beatriz; Graeve de Oliveira, Emmanuel
2010-03-01
The Drell-Yan dilepton production at backward rapidities is studied in proton-nucleus collisions at Relativistic Heavy Ion Collider and LHC energies by comparing two different approaches: the k{sub T} factorization at next-to-leading order with intrinsic transverse momentum and the same process formulated in the target rest frame, i.e., the color dipole approach. Our results are expressed in terms of the ratio between p(d)-A and p-p collisions as a function of transverse momentum and rapidity. Three nuclear parton distribution functions are used: EKS (Eskola, Kolhinen, and Ruuskanen), EPS08, and EPS09 and, in both approaches, dileptons show sensitivity to nuclear effects, specially regarding the intrinsic transverse momentum. Also, there is room to discriminate between formalisms: the color dipole approach lacks soft effects introduced by the intrinsic k{sub T}. Geometric scaling GBW (Golec-Biernat and Wusthoff) and BUW (Boer, Utermann, and Wessels) color dipole cross section models and also a DHJ (Dumitru, Hayashigaki, and Jalilian-Marian) model, which breaks geometric scaling, are used. No change in the ratio between collisions is observed, showing that this observable is not changed by the particular shape of the color dipole cross section. Furthermore, our k{sub T} factorization results are compared with color glass condensate results at forward rapidities: the results agree at Relativistic Heavy Ion Collider although disagree at LHC, mainly due to the different behavior of target gluon and quark shadowing.
NASA Astrophysics Data System (ADS)
Voschula, I. V.; Dlugunovich, V. A.; Zhumar, A. Yu.
2013-05-01
Stokes parameters were measured for radiation reflected in the range 5° to 80° by silver-colored, white, and black thermal control coatings deposited on an aluminum alloy substrate, by green paint on a phenolic plastic surface, and by uncoated carbon-fiber reinforced plastic illuminated by linearly polarized He-Ne laser radiation at an incident angle of -5°. The bidirectional reflectance distribution function of the investigated samples was determined as a function of the view zenith angle.
Dumitru, Adrian; Lappi, Tuomas; Skokov, Vladimir
2015-12-17
In this study, we determine the distribution of linearly polarized gluons of a dense target at small x by solving the Balitsky–Jalilian-Marian–Iancu–McLerran–Weigert–Leonidov–Kovner rapidity evolution equations. From these solutions, we estimate the amplitude of cos2Φ azimuthal asymmetries in deep inelastic scattering dijet production at high energies. We find sizable long-range in rapidity azimuthal asymmetries with a magnitude in the range of v_{2}=
Dumitru, Adrian; Lappi, Tuomas; Skokov, Vladimir
2015-12-17
In this study, we determine the distribution of linearly polarized gluons of a dense target at small x by solving the Balitsky–Jalilian-Marian–Iancu–McLerran–Weigert–Leonidov–Kovner rapidity evolution equations. From these solutions, we estimate the amplitude of cos2Φ azimuthal asymmetries in deep inelastic scattering dijet production at high energies. We find sizable long-range in rapidity azimuthal asymmetries with a magnitude in the range of v2=~10%.
Hussain, Tariq; Kaialy, Waseem; Deng, Tong; Bradley, Mike S A; Nokhodchi, Ali; Armour-Chélu, David
2013-01-30
Electrostatic charge is generated during powder handling due to particle-particle and particle-wall collisions, rubbing, sliding, and rolling. In case of bipolar charge generation, the electrostatic forces may significantly change the inner forces and increase powder adhesion and cause a serious problem in material handling process. Therefore, the knowledge of distribution of charge across the individual particles is helpful to identify the role of triboelectrification and the effects of various relevant variables especially change in the contact materials, environmental conditions during processing, etc. A novel approach based on inductive sensor has been developed to detect the either polarity of charged particle and to characterise the bipolar charge distribution in the population of particulate material. To achieve this, an amplification unit configured as a pure integrator and signal processing techniques has been used to de-noise and correct the baseline of signal and MATLAB algorithm developed for peak detection. The polarity of charged particles obtained by this method is calibrated with Faraday pail method and the results are promising. Experimental study has been carried out by using two distinct populations of oppositely charged particles (glass beads-PVC, olivine sand, and silica sand). The obtained results indicate that the method is able to detect the distribution of polarities of charged particles.
NASA Astrophysics Data System (ADS)
Alexandru, Andrei; Draper, Terrence; Horváth, Ivan; Streuer, Thomas
2011-08-01
We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left-right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of "low" and "high" Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD.
Application of composite flow laws to grain size distributions derived from polar ice cores
NASA Astrophysics Data System (ADS)
Binder, Tobias; de Bresser, Hans; Jansen, Daniela; Weikusat, Ilka; Garbe, Christoph; Kipfstuhl, Sepp
2014-05-01
Apart from evaluating the crystallographic orientation, focus of microstructural analysis of natural ice during the last decades has been to create depth-profiles of mean grain size. Several ice flow models incorporated mean grain size as a variable. Although such a mean value may coincide well with the size of a large proportion of the grains, smaller/larger grains are effectively ignored. These smaller/larger grains, however, may affect the ice flow modeling. Variability in grain size is observed on centimeter, meter and kilometer scale along deep polar ice cores. Composite flow laws allow considering the effect of this variability on rheology, by weighing the contribution of grain-size-sensitive (GSS, diffusion/grain boundary sliding) and grain-size-insensitive (GSI, dislocation) creep mechanisms taking the full grain size distribution into account [1]. Extraction of hundreds of grain size distributions for different depths along an ice core has become relatively easy by automatic image processing techniques [2]. The shallow ice approximation is widely adopted in ice sheet modeling and approaches the full-Stokes solution for small ratios of vertical to horizontal characteristic dimensions. In this approximation shear stress in the vertical plain dominates the strain. This assumption is not applicable at ice divides or dome structures, where most deep ice core drilling sites are located. Within the upper two thirds of the ice column longitudinal stresses are not negligible and ice deformation is dominated by vertical strain. The Dansgaard-Johnsen model [3] predicts a dominating, constant vertical strain rate for the upper two thirds of the ice sheet, whereas in the lower ice column vertical shear becomes the main driver for ice deformation. We derived vertical strain rates from the upper NEEM ice core (North-West Greenland) and compared them to classical estimates of strain rates at the NEEM site. Assuming intervals of constant accumulation rates, we found a
Zhang, Rong; Wang, Xiangzhao; Cheng, Xin; Qiu, Zicheng
2010-11-01
When propagating in free space, the transversal distribution of the degree of polarization of an anisotropic electromagnetic Gaussian-Schell model (AEGSM) beam will generally undergo a complex evolution process. We find that this transversal distribution of the degree of polarization of an AEGSM beam can be controlled by exploiting the partial correlation properties of the source. The main research of our paper falls into two parts. First, the concept of analogical propagation of the transversal distribution of the degree of polarization is proposed, and the condition for an AEGSM beam having an analogical propagation is obtained. When an AEGSM beam is on analogical propagation, the distribution of the degree of polarization on any cross section of the beam is always similar to that on the source plane, except that the size of the distribution pattern will expand continuously as the propagation distance increases. Second, the far-field transversal distribution of the degree of polarization is considered, and the condition for the far-field transversal polarization distribution of an AEGSM beam to be always of circularly symmetric shape, no matter how complicated it is on the source, is obtained. Our research is expected to find applications in areas that make use of the polarization properties of random electromagnetic beams.
McGreevy, Erica M.; Vijayraghavan, Deepthi; Davidson, Lance A.; Hildebrand, Jeffrey D.
2015-01-01
ABSTRACT Neural tube closure is a critical developmental event that relies on actomyosin contractility to facilitate specific processes such as apical constriction, tissue bending, and directional cell rearrangements. These complicated processes require the coordinated activities of Rho-Kinase (Rock), to regulate cytoskeletal dynamics and actomyosin contractility, and the Planar Cell Polarity (PCP) pathway, to direct the polarized cellular behaviors that drive convergent extension (CE) movements. Here we investigate the role of Shroom3 as a direct linker between PCP and actomyosin contractility during mouse neural tube morphogenesis. In embryos, simultaneous depletion of Shroom3 and the PCP components Vangl2 or Wnt5a results in an increased liability to NTDs and CE failure. We further show that these pathways intersect at Dishevelled, as Shroom3 and Dishevelled 2 co-distribute and form a physical complex in cells. We observed that multiple components of the Shroom3 pathway are planar polarized along mediolateral cell junctions in the neural plate of E8.5 embryos in a Shroom3 and PCP-dependent manner. Finally, we demonstrate that Shroom3 mutant embryos exhibit defects in planar cell arrangement during neural tube closure, suggesting a role for Shroom3 activity in CE. These findings support a model in which the Shroom3 and PCP pathways interact to control CE and polarized bending of the neural plate and provide a clear illustration of the complex genetic basis of NTDs. PMID:25596276
NASA Astrophysics Data System (ADS)
Fanelli, C.; Cisbani, E.; Hamilton, D. J.; Salmé, G.; Wojtsekhowski, B.; Ahmidouch, A.; Annand, J. R. M.; Baghdasaryan, H.; Beaufait, J.; Bosted, P.; Brash, E. J.; Butuceanu, C.; Carter, P.; Christy, E.; Chudakov, E.; Danagoulian, S.; Day, D.; Degtyarenko, P.; Ent, R.; Fenker, H.; Fowler, M.; Frlez, E.; Gaskell, D.; Gilman, R.; Horn, T.; Huber, G. M.; de Jager, C. W.; Jensen, E.; Jones, M. K.; Kelleher, A.; Keppel, C.; Khandaker, M.; Kohl, M.; Kumbartzki, G.; Lassiter, S.; Li, Y.; Lindgren, R.; Lovelace, H.; Luo, W.; Mack, D.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.; Maxwell, J.; Mbianda, G.; Meekins, D.; Meziane, M.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Mulholland, J.; Nelyubin, V.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Prok, Y.; Puckett, A. J. R.; Punjabi, V.; Shabestari, M.; Shahinyan, A.; Slifer, K.; Smith, G.; Solvignon, P.; Subedi, R.; Wesselmann, F. R.; Wood, S.; Ye, Z.; Zheng, X.
2015-10-01
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70 ° . The longitudinal transfer KLL, measured to be 0.645 ±0.059 ±0.048 , where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ˜3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
Fanelli, C; Cisbani, E; Hamilton, D J; Salmé, G; Wojtsekhowski, B; Ahmidouch, A; Annand, J R M; Baghdasaryan, H; Beaufait, J; Bosted, P; Brash, E J; Butuceanu, C; Carter, P; Christy, E; Chudakov, E; Danagoulian, S; Day, D; Degtyarenko, P; Ent, R; Fenker, H; Fowler, M; Frlez, E; Gaskell, D; Gilman, R; Horn, T; Huber, G M; de Jager, C W; Jensen, E; Jones, M K; Kelleher, A; Keppel, C; Khandaker, M; Kohl, M; Kumbartzki, G; Lassiter, S; Li, Y; Lindgren, R; Lovelace, H; Luo, W; Mack, D; Mamyan, V; Margaziotis, D J; Markowitz, P; Maxwell, J; Mbianda, G; Meekins, D; Meziane, M; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Mulholland, J; Nelyubin, V; Pentchev, L; Perdrisat, C F; Piasetzky, E; Prok, Y; Puckett, A J R; Punjabi, V; Shabestari, M; Shahinyan, A; Slifer, K; Smith, G; Solvignon, P; Subedi, R; Wesselmann, F R; Wood, S; Ye, Z; Zheng, X
2015-10-09
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
NASA Astrophysics Data System (ADS)
Sargsian, Misak; Cosyn, Wim; Weiss, Christian
2015-10-01
For the past several years there have been an intensive research and development for the possible electron-ion collider that will be able to probe deep inelastic processes at unprecedentedly high energies in eA channel. One of the important advantages of the collider kinematics in DIS processes is the possibility for an unambiguous separation of hadrons emerging from DIS and hadrons fragmenting from the target nucleus. This creates a unique possibility for tagging the interacting nucleon with the recoil slow fragments in the DIS process. The situation is most clean for the deuteron target in which case the recoil particle is a nucleon. In addition, the possibility of having polarized deuteron beams will create unprecedented opportunities in probing polarization degrees of freedom for parton distributions in the interacting bound nucleon. In this work we develop a theoretical framework for the polarized electron-polarized deuteron deep inelastic scattering in which the recoil nucleon is detected in the target fragmentation region. Two main contributions for which theoretical models are developed are the plane-wave impulse approximation, in which no reinteractions are taking place between the final state products of DIS and the recoil nucleon.
Hayward, R.K.
2011-01-01
The Mars Global Digital Dune Database (MGD3) now extends from 90??N to 65??S. The recently released north polar portion (MC-1) of MGD3 adds ~844 000km2 of moderate- to large-size dark dunes to the previously released equatorial portion (MC-2 to MC-29) of the database. The database, available in GIS- and tabular-format in USGS Open-File Reports, makes it possible to examine global dune distribution patterns and to compare dunes with other global data sets (e.g. atmospheric models). MGD3 can also be used by researchers to identify areas suitable for more focused studies. The utility of MGD3 is demonstrated through three example applications. First, the uneven geographic distribution of the dunes is discussed and described. Second, dune-derived wind direction and its role as ground truth for atmospheric models is reviewed. Comparisons between dune-derived winds and global and mesoscale atmospheric models suggest that local topography may have an important influence on dune-forming winds. Third, the methods used here to estimate north polar dune volume are presented and these methods and estimates (1130km3 to 3250km3) are compared with those of previous researchers (1158km3 to 15 000km3). In the near future, MGD3 will be extended to include the south polar region. ?? 2011 by John Wiley and Sons, Ltd.
Photon parton distributions in nuclei and the EMC effect
Frankfurt, L.; Strikman, M.
2010-12-15
Photons, as well as quarks and gluons, are constituents of the infinite momentum frame (IMF) wave function of an energetic particle. They are mostly equivalent photons whose amplitude follows from the Lorentz transformation of the particle rest frame Coulomb field into the IMF and from the conservation of the electromagnetic current. We evaluate in a model independent way the dominant photon contribution {proportional_to}{alpha}{sub em}(Z{sup 2}/A{sup 4/3})ln(1/R{sub A}m{sub N}x) to the nuclear structure functions as well as the term {proportional_to}{alpha}{sub em}Z/A. In addition we show that the definition of x consistent with the exact kinematics of eA scattering (with exact sum rules) works in the same direction as the nucleus field of equivalent photons. Combined, these effects account for the bulk of the hadronic European Muon Collaboration (EMC) effect for x{<=}0.5 where Fermi motion effects are small. In particular, for these x the hadronic mechanism contribution to the EMC effect does not exceed {approx}3% for all nuclei. Also, the A dependence of the hadronic mechanism of the EMC effect for x>0.5 is significantly modified.
Parton distributions with the combined HERA charm production cross sections
Bertone, Valerio; Rojo, Juan
2013-04-15
Heavy quark structure functions from HERA provide a direct handle on the medium and small-x gluon PDF. In this contribution, we discuss ongoing progress on the implementation of the FONLL General-Mass scheme with running heavy quark masses, and of its benchmarking with the HOPPET and OpenQCDrad codes, and then present the impact of the recently released combined HERA charm production cross sections in the NNPDF 2.3 analysis. We find that the combined charm data contribute to constraining the gluon and quarks at small values of Bjorken-x.
Photon parton distributions in nuclei and the EMC effect
Frankfurt, Leonid; Strikman, Mark
2010-12-01
Photons as well as quarks and gluons are constituents of the infinite momentum frame (IMF) wave function of an energetic particle. They are mostly equivalent photons whose amplitude follows from the Lorentz transformation of the particle rest frame Coulomb field into the IMF and from the conservation of the electromagnetic current. We evaluate in a model independent way the dominant photon contribution \\propto \\alpha_{em}(Z^2/A^{4/3})\\ln(1/R_{A}m_{N}x) to the nuclear structure functions as well as the term \\propto \\alpha_{em}Z/A. In addition we show that the definition of x consistent with the exact kinematics of eA scattering (with exact sum rules) works in the same direction as the nucleus field of equivalent photons. Combined, these effects account for the bulk of the EMC effect for x\\le 0.5 where Fermi motion effects are small. In particular for these x the hadronic mechanism contribution to the EMC effect does not exceed \\sim 3% for all nuclei. Also the A-dependence of the hadronic mechanism of the EMC effect for x > 0.5 is significantly modified.
The actin cytoskeleton may control the polar distribution of an auxin transport protein
NASA Technical Reports Server (NTRS)
Muday, G. K.; Hu, S.; Brady, S. R.; Davies, E. (Principal Investigator)
2000-01-01
The gravitropic bending of plants has long been linked to the changes in the transport of the plant hormone auxin. To understand the mechanism by which gravity alters auxin movement, it is critical to know how polar auxin transport is initially established. In shoots, polar auxin transport is basipetal (i.e., from the shoot apex toward the base). It is driven by the basal localization of the auxin efflux carrier complex. One mechanism for localizing this efflux carrier complex to the basal membrane may be through attachment to the actin cytoskeleton. The efflux carrier protein complex is believed to consist of several polypeptides, including a regulatory subunit that binds auxin transport inhibitors, such as naphthylphthalamic acid (NPA). Several lines of experimentation have been used to determine if the NPA binding protein interacts with actin filaments. The NPA binding protein has been shown to partition with the actin cytoskeleton during detergent extraction. Agents that specifically alter the polymerization state of the actin cytoskeleton change the amount of NPA binding protein and actin recovered in these cytoskeletal pellets. Actin-affinity columns were prepared with polymers of actin purified from zucchini hypocotyl tissue. NPA binding activity was eluted in a single peak from the actin filament column. Cytochalasin D, which fragments the actin cytoskeleton, was shown to reduce polar auxin transport in zucchini hypocotyls. The interaction of the NPA binding protein with the actin cytoskeleton may localize it in one plane of the plasma membrane, and thereby control the polarity of auxin transport.
NASA Astrophysics Data System (ADS)
Nefedov, M. A.; Saleev, V. A.
2015-11-01
The hadroproduction of prompt isolated photon pairs at high energies is studied in the framework of the parton Reggeization approach. The real part of the NLO corrections is computed (the NLO⋆ approximation), and the procedure for the subtraction of double counting between real parton emissions in the hard-scattering matrix element and unintegrated parton distribution function is constructed for the amplitudes with Reggeized quarks in the initial state. The matrix element of the important next-to-next-to-leading-order subprocess R R →γ γ with full dependence on the transverse momenta of the initial-state Reggeized gluons is obtained. We compare obtained numerical results with diphoton spectra measured at the Tevatron and the LHC and find a good agreement of our predictions with experimental data at the high values of diphoton transverse momentum, pT, and especially at the pT larger than the diphoton invariant mass, M . In this multi-Regge kinematics region, the NLO correction is strongly suppressed, demonstrating the self-consistency of the parton Reggeization approach.
NASA Technical Reports Server (NTRS)
Zhu, P. Y.
1991-01-01
The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.
MacIas-Perez, J. F.; Mayet, F.; Aumont, J.
2010-03-01
Within the framework of the Planck satellite polarization calibration, we present a study of the Crab Nebula spectral energy distribution (SED) over more than six decades in frequency ranging from 1 to 10{sup 6} GHz (from 299 to 2.99 x 10{sup -4} mm). The Planck satellite mission observes the sky from 30 to 857 GHz (from 9.99 to 0.3498 mm) and therefore we focus on the millimeter region. We use radio and submillimeter data from the WMAP satellite between 23 and 94 GHz (from 13 to 3.18 mm), from the Archeops balloon experiment between 143 (2.1 mm) and 545 GHz (0.55 mm), and a compendium of other Crab Nebula observations. The Crab SED is compared to models including three main components: synchrotron that is responsible for the emission at low and high frequencies, dust that explains the excess of flux observed by the IRAS satellite, and an extra component on the millimeter regime. From this analysis, we conclude that the unpolarized emission of the Crab Nebula at microwave and millimeter wavelengths is the same synchrotron emission as the one observed in the radio domain. Therefore, we expect the millimeter emission of the Crab Nebula to be polarized with the same degree of polarization and orientation as the radio emission. We set upper limits on the possible errors induced by any millimeter extra component on the reconstruction of the degree and angle of polarization at the percent level as a maximum. This result strongly supports the choice by the Planck collaboration of the Crab Nebula emission for performing polarization cross-checks in the range 30 (299 mm) to 353 GHz (0.849 mm).
Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography
Boer, Daniel; Diehl, Markus; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; /more authors..
2012-06-07
This report on the science case for an Electron-Ion Collider (EIC) is the result of a ten-week program at the Institute for Nuclear Theory (INT) in Seattle (from September 13-November 19, 2010), motivated by the need to develop a strong case for the continued study of the QCD description of hadron structure in the coming decades. Hadron structure in the valence quark region will be studied extensively with the Jefferson Lab 12 GeV science program, the subject of an INT program the previous year. The focus of the INT program was on understanding the role of gluons and sea quarks, the important dynamical degrees of freedom describing hadron structure at high energies. Experimentally, the most direct and precise way to access the dynamical structure of hadrons and nuclei at high energies is with a high luminosity lepton probe in collider mode. An EIC with optimized detectors offers enormous potential as the next generation accelerator to address many of the most important, open questions about the fundamental structure of matter. The goal of the INT program, as captured in the writeups in this report, was to articulate these questions and to identify golden experiments that have the greatest potential to provide definitive answers to these questions. At resolution scales where quarks and gluons become manifest as degrees of freedom, the structure of the nucleon and of nuclei is intimately connected with unique features of QCD dynamics, such as confinement and the self-coupling of gluons. Information on hadron sub-structure in DIS is obtained in the form of 'snapshots' by the 'lepton microscope' of the dynamical many-body hadron system, over different momentum resolutions and energy scales. These femtoscopic snapshots, at the simplest level, provide distribution functions which are extracted over the largest accessible kinematic range to assemble fundamental dynamical insight into hadron and nuclear sub-structure. For the proton, the EIC would be the brightest
Roy, G; Bissonnette, L; Bastille, C; Vallée, G
1999-08-20
Multiple-field-of-view (MFOV) secondary-polarization lidar signals are used to calculate the particle-size density distribution (PSD) at the base of a cloud. At the cloud base, multiple scattering is weak and single backscattering is predominant by many orders of magnitude. Because secondary polarization is a direct measure of multiple scattering, it is therefore advantageous to use secondary polarization. A mathematical relation among the PSD, the lidar fields of view, the scattering angles, and the angular depolarization is derived to facilitate use of secondary polarization. The model is supported by experimental MFOV lidar measurements carried out in a controlled environment, and its limitations and restrictions are discussed.
Maltoni, Fabio; Mawatari, Kentarou; Zaro, Marco
Vector-boson fusion and associated production at the LHC can provide key information on the strength and structure of the Higgs couplings to the Standard Model particles. Using an effective field theory approach, we study the effects of next-to-leading order (NLO) QCD corrections matched to a parton shower on selected observables for various spin-0 hypotheses. We find that inclusion of NLO corrections is needed to reduce the theoretical uncertainties on the total rates as well as to reliably predict the shapes of the distributions. Our results are obtained in a fully automatic way via FeynRules and MadGraph5_aMC@NLO.
Ultraviolet observations of the Saturnian north aurora and polar haze distribution with the HST-FOC
NASA Technical Reports Server (NTRS)
Gerard, J. C.; Dols, V.; Grodent, D.; Waite, J. H.; Gladstone, G. R.; Prange, R.
1995-01-01
Near simultaneous observations of the Saturnian H2 north ultraviolet aurora and the polar haze were made at 153 nm and 210 nm respectively with the Faint Object Camera on board the Hubble Space Telescope. The auroral observations cover a complete rotation of the planet and, when co-added, reveal the presence of an auroral emission near 80 deg N with a peak brightness of about 150 kR of total H2 emission. The maximum optical depth of the polar haze layer is found to be located approximately 5 deg equatorward of the auroral emission zone. The haze particles are presumably formed by hydrocarbon aerosols initiated by H2+ auroral production. In this case, the observed haze optical depth requires an efficiency of aerosol formation of about 6 percent, indicating that auroral production of hydrocarbon aerosols is a viable source of high-latitude haze.
Water on Mars: Inventory, distribution, and possible sources of polar ice
NASA Technical Reports Server (NTRS)
Clifford, S. M.
1992-01-01
Theoretical considerations and various lines of morphologic evidence suggest that, in addition to the normal seasonal and climatic exchange of H2O that occurs between the Martian polar caps, atmosphere, and mid to high latitude regolith, large volumes of water have been introduced into the planet's long term hydrologic cycle by the sublimation of equatorial ground ice, impacts, catastrophic flooding, and volcanism. Under the climatic conditions that are thought to have prevailed on Mars throughout the past 3 to 4 b.y., much of this water is expected to have been cold trapped at the poles. The amount of polar ice contributed by each of the planet's potential crustal sources is discussed and estimated. The final analysis suggests that only 5 to 15 pct. of this potential inventory is now in residence at the poles.
Hybrid mode-locked erbium-doped all-fiber soliton laser with a distributed polarizer.
Chernykh, D S; Krylov, A A; Levchenko, A E; Grebenyukov, V V; Arutunyan, N R; Pozharov, A S; Obraztsova, E D; Dianov, E M
2014-10-10
A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.
NASA Astrophysics Data System (ADS)
Yang, Haifeng; Yang, Xiaoping; Sun, Xuna; Liu, Jun; Yang, Yong
2016-09-01
Parallel processing is the forefront of femtosecond laser micro-nano processing. The key to parallel processing is obtaining multichannel parallel femtosecond laser beams. A method of spatial parallel pulse splitting based on birefringence properties of polarizing splitting prism is proposed for obtaining multichannel parallel ultra-short pulse trains. The generated sub-pulses have the characteristics of equal energy and high similarity. More than that, the compact structure of the polarizing splitting prism makes it easier to be implemented. The accurate relationship between the space interval of pulse sequences and the structural angle, dimension and the distance between the two prisms is mathematically derived. The realizable array form of sub-pulse sequences is theoretically analyzed. The feasibility of the proposed method of femtosecond laser parallel processing is analyzed by software simulation and numerical calculation. The results will provide a new research direction for application of ultrashort pulse in parallel processing.
1992-01-01
We compared the surface envelope glycoprotein distribution and the budding polarity of four RNA viruses in Fischer rat thyroid (FRT) cells and in CaCo-2 cells derived from a human colon carcinoma. Whereas both FRT and CaCo-2 cells sort similarly influenza hemagglutinin and vesicular stomatitis virus (VSV) G protein, respectively, to apical and basolateral membrane domains, they differ in their handling of two togaviruses, Sindbis and Semliki Forest virus (SFV). By conventional EM Sindbis virus and SFV were shown to bud apically in FRT cells and basolaterally in CaCo-2 cells. Consistent with this finding, the distribution of the p62/E2 envelope glycoprotein of SFV, assayed by immunoelectronmicroscopy and by domain-selective surface biotinylation was predominantly apical on FRT cells and basolateral on CaCo-2 cells. We conclude that a given virus and its envelope glycoprotein can be delivered to opposite membrane domains in epithelial cells derived from different tissues. The tissue specificity in the polarity of virus budding and viral envelope glycoprotein distribution indicate that the sorting machinery varies considerably between different epithelial cell types. PMID:1572895
Polarity-dependent distribution of angiomotin localizes Hippo signaling in preimplantation embryos
Hirate, Yoshikazu; Hirahara, Shino; Inoue, Ken-ichi; Suzuki, Atsushi; Alarcon, Vernadeth B.; Akimoto, Kazunori; Hirai, Takaaki; Hara, Takeshi; Adachi, Makoto; Chida, Kazuhiro; Ohno, Shigeo; Marikawa, Yusuke; Nakao, Kazuki; Shimono, Akihiko; Sasaki, Hiroshi
2013-01-01
Summary Background In preimplantation mouse embryos, the first cell fate specification to the trophectoderm or inner cell mass occurs by the early blastocyst stage. The cell fate is controlled by cell position-dependent Hippo signaling, although the mechanisms underlying position-dependent Hippo signaling are unknown. Results We showed that a combination of cell polarity and cell–cell adhesion establishes position-dependent Hippo signaling, where the outer and inner cells are polar and nonpolar, respectively. The junction-associated proteins angiomotin (Amot) and Amotl2 are essential for Hippo pathway activation and appropriate cell fate specification. In the nonpolar inner cells, Amot localizes to adherens junctions (AJs) and cell–cell adhesion activates the Hippo pathway. In the outer cells, the cell polarity sequesters Amot from basolateral AJs to apical domains, thereby suppressing Hippo signaling. The N-terminal domain of Amot is required for actin binding, Nf2/Merlin-mediated association with the E-cadherin complex, and interaction with Lats protein kinase. In AJs, Ser176 in the N-terminal domain of Amot is phosphorylated by Lats, which inhibits the actin-binding activity, thereby stabilizing the Amot–Lats interaction to activate the Hippo pathway. Conclusion We propose that the phosphorylation of S176 in Amot is a critical step for activation of the Hippo pathway in AJs and that cell polarity disconnects the Hippo pathway from cell–cell adhesion by sequestering Amot from AJ. This mechanism converts positional information into differential Hippo signaling, thereby leading to differential cell fates. PMID:23791731
Interference effect in elastic parton energy loss in a finitemedium
Wang, Xin-Nian
2005-04-18
Similar to the radiative parton energy loss due to gluonbremsstrahlung, elastic energy loss of a parton undergoing multiplescattering in a finite medium is demonstrated to be sensitive tointerference effect. The interference between amplitudes of elasticscattering via a gluon exchange and that of gluon radiation reduces theeffective elastic energy loss in a finite medium and gives rise to anon-trivial length dependence. The reduction is most significant for apropagation length L<4/\\pi T in a medium with a temperature T. Thoughthe finite size effect is not significant for the average partonpropagation in the most central heavy-ion collisions, it will affect thecentrality dependence of its effect on jet quenching.
Double Parton Interactions in pp and pA Collisions
NASA Astrophysics Data System (ADS)
Treleani, Daniele; Calucci, Giorgio; Salvini, Simona
2016-11-01
As a consequence of the increasingly large flux of partons at small x, Double Parton Interactions (DPI) play an increasingly important role at high energies. A detail understanding of DPI dynamics is therefore mandatory, for a reliable subtraction of the background in the search of new physics. On the other hand, DPI are an interesting topic of research by themselves, as DPI probe the hadron structure in a rather different way, as compared with the large pt processes usually considered. In this note we will make a short illustration of some of the main features characterizing DPI in pp and in pA collisions.
Dong Li; Xiu Xiaoming; Gao Yajun; Yi, X. X.
2011-10-15
Using three-photon polarization-entangled GHZ states or W states, we propose controlled quantum key distribution protocols for circumventing two main types of collective noise, collective dephasing noise, or collective rotation noise. Irrespective of the number of controllers, a three-photon state can generate a one-bit secret key. The storage technique of quantum states is dispensable for the controller and the receiver, and it therefore allows performing the process in a more convenient mode. If the photon cost in a security check is disregarded, then the efficiency theoretically approaches unity.
Dong, Yongkang; Bao, Xiaoyi; Chen, Liang
2009-09-01
We demonstrate a time-domain distributed temperature sensing based on birefringence effect on transient Brillouin grating (TBG) in a polarization-maintaining photonic crystal fiber (PM-PCF), which uses two short pump pulses (2 ns) to excite a TBG and a long probe pulse (6 ns) to map the transient Brillouin grating spectrum (TBGS) associated with the birefringence. The 2 ns pump pulses defines a spatial resolution of 20 cm and a temperature measurement range of a few hundred degrees Celsius, and the long probe pulse provides a narrow TBGS with a temperature resolution of 0.07 degrees C.
Ling, G N; Niu, Z; Ochsenfeld, M
1993-01-01
We determined the equilibrium distribution of twenty-one nonmetabolized nonelectrolytes in frog muscle cells. In all cases, plots of the equilibrium intracellular concentrations of a solute in the cell water against the external concentrations of the solute yielded straight lines in agreement with the prediction of such a rectilinear plot by the polarized multilayer (PM) theory. The slopes of these straight lines yield the equilibrium distribution coefficients or q-value of that solute. It was shown that, again in agreement with the PM theory, the q-values of fourteen nonelectrolytes vary with the molecular volumes of the nonelectrolytes, obeying the "size rule", i.e., the larger the solute, the lower its q-value. The q-values of the remaining seven nonelectrolytes also decrease with their molecular volumes but on a separate curve. These q-value vs. molecular volume plots (q-v plots) show strong resemblance to similar q-v plots of solutes in dialysis sacs containing proteins and polymers assuming the fully-extended conformation (extrovert models) but no, or only weak, resemblance to q-v plots of solutions containing native globular proteins (introvert models). These findings also support the PM theory, according to which some protein(s) pervasively present in cells are in the fully-extended conformation; and that these fully extended cell protein(s) polarize(s) in multilayers all or virtually all cell water. The relationship between the q-values of the nonelectrolytes and the solutes' respective molecular volume are described by two sets of theoretical curves, calculated from an equation introduced in the preceding paper. Both curves were computed on the basis of the same exclusion intensity (Uvp = 126 cal/mole). This factor measures the extra water-to-water interaction of the polarized water which acts to keep solute out of the cell water in degree according to the size of the solute. The two curves are computed on the basis of two different values of U(s), which
Bechshøft, T Ø; Jakobsen, J; Sonne, C; Dietz, R
2011-08-15
Vitamins A and E content of inner organs, among these the kidneys, are increasingly being used as an indicator of adverse effects caused to the organism by e.g. environmental contaminants. In general, only a renal sub sample is used for analyses, and it is thus essential to know which part of the organ to sample in order to get a representative value for this important biomarker. The aim here was to assess the distribution of vitamins A (retinol) and E (α-tocopherol) within the polar bear multireniculate kidney (i.e. polar vs. medial position) and also within the cortex vs. medulla of each separate renculi. The results showed no significant difference between the medial and polar renculi with regards to either retinol (p=0.44) or α-tocopherol (p=0.75). There were, however, significant differences between cortex and medulla for both vitamins (retinol, p=0.0003; α-tocopherol, p<0.0001). The kidney cortex contained higher values of both vitamins than the medulla; on average 29% more retinol and 57% more α-tocopherol. Mean concentrations in the medulla was 2.7 mg/kg for retinol and 116 mg/kg for α-tocopherol, and in the cortex 3.5 mg/kg for retinol and 182 mg/kg for α-tocopherol. These results clearly indicate that one should take precautions when analyzing retinol and α-tocopherol in polar bear kidneys. Prior to analysis, the renculi should be separated into medulla and cortex. The results indicated no significant differences between renculi from different parts of the kidney.
Xin Qian
2012-06-01
Parton distribution functions, which represent the flavor and spin structure of the nucleon, provide invaluable information in illuminating quantum chromodynamics in the confinement region. Among various processes that measure such parton distribution functions, semi-inclusive deep inelastic scattering is regarded as one of the golden channels to access transverse momentum dependent parton distribution functions, which provide a 3-D view of the nucleon structure in momentum space. The Jefferson Lab experiment E06-010 focuses on measuring the target single and double spin asymmetries in the 3He(e, e'pi+,-)X reaction with a transversely polarized 3He target in Hall A with a 5.89 GeV electron beam. A leading pion and the scattered electron are detected in coincidence by the left High-Resolution Spectrometer at 16{sup o} and the BigBite spectrometer at 30{sup o} beam right, respectively. The kinematic coverage concentrates in the valence quark region, x {approx} 0.1-0.4, at Q2 {approx}1-3 Gev{sub 2}. The Collins and Sivers asymmetries of 3He and neutron are extracted. In this review, an overview of the experiment and the final results are presented. Furthermore, an upcoming 12-GeV program with a large acceptance solenoidal device and the future possibilities at an electron-ion collider are discussed.
NASA Astrophysics Data System (ADS)
von Neumann-Cosel, Peter
2012-02-01
Small-angle polarized proton scattering including 0° at incident energies of a few 100 MeV/nucleon is established as a new spectrospcopic tool for the study of E1 and M1 strength distributions. Experiments of this type have been realized recently at RCNP, Osaka, Japan with high energy resolution of the order 25 - 30 keV (FWHM). Using 208Pb as an example, the physics potential of such data is discussed. It includes information on the properties of the Pygmy Dipole Resonance but also on complete E1 and M1 strength distributions and thus the gamma strength function. The E1 polarizability can be extracted with a precision of about 4% providing important experimental constraints on the neutron skin thickness in 208Pb.
Polarized cells, polar actions.
Maddock, J R; Alley, M R; Shapiro, L
1993-11-01
The recognition of polar bacterial organization is just emerging. The examples of polar localization given here are from a variety of bacterial species and concern a disparate array of cellular functions. A number of well-characterized instances of polar localization of bacterial proteins, including the chemoreceptor complex in both C. crescentus and E. coli, the maltose-binding protein in E. coli, the B. japonicum surface attachment proteins, and the actin tail of L. monocytogenes within a mammalian cell, involve proteins or protein complexes that facilitate bacterial interaction with the environment, either the extracellular milieux or that within a plant or mammalian host. The significance of this observation remains unclear. Polarity in bacteria poses many problems, including the necessity for a mechanism for asymmetrically distributing proteins as well as a mechanism by which polar localization is maintained. Large structures, such as a flagellum, are anchored at the pole by means of the basal body that traverses the peptidoglycan wall. But for proteins and small complexes, whether in the periplasm or the membrane, one must invoke a mechanism that prevents the diffusion of these proteins away from the cell pole. Perhaps the periplasmic proteins are retained at the pole by the presence of the periseptal annulus (35). The constraining features for membrane components are not known. For large aggregates, such as the clusters of MCP, CheA, and CheW complexes, perhaps the size of the aggregate alone prevents displacement. In most cases of cellular asymmetry, bacteria are able to discriminate between the new pole and the old pole and to utilize this information for localization specificity. The maturation of new pole to old pole appears to be a common theme as well. Given numerous examples reported thus far, we propose that bacterial polarity displays specific rules and is a more general phenomenon than has been previously recognized.
Effects of the Sea Ice Floe Size Distribution on Polar Ocean Properties and Air-Sea Exchange
NASA Astrophysics Data System (ADS)
Horvat, C.; Tziperman, E.
2014-12-01
Recent scientific studies have demonstrated that sub-mesoscale ocean eddies, motions characterized by Rossby and Richardson numbers around 1, are important in determining the vertical density structure of the ocean, particularly in the mixed layer. Instabilities excited at the sub-mesoscale have timescales of days and length scales of less than 10 kilometers, and enhance ocean restratification by slumping lateral density gradients. In the polar oceans, a unique mechanism exists that may generate motions on these scales. Individual floes of sea ice may create lateral gradients in the ocean surface heat flux and wind stress curl, acting as an insulator and physical barrier between the ocean and the atmospheric processes that destabilize it. The "floe size distribution" describes the fraction of the ocean surface area covered by sea ice floes, as a function of the sea ice floe size, and determines the length scales over which gradients in atmospheric forcing are transmitted to the ocean. It may therefore play a significant role in exciting or inhibiting sub-mesoscale eddies, and consequently in restratification and air-sea exchange. Current GCMs simulate ice cover using grid-scale ice fraction alone, and lack information about the floe size distribution and of ice length scales that may be important in setting the larger-scale statistics of these motions. An important factor in determining the properties of the upper polar oceans might therefore be missing from modern GCMs. We consider this possibility by examining sub-mesoscale resolving ocean GCM experiments coupled to an energy-balanced atmosphere and idealized model of floes of sea ice. Varying the floe size distribution with a fixed sea ice fraction, we find that the length scales of individual floes and the floe size distribution itself play an important role in setting the steady-state ocean stratification, temperature, and air-sea exchange.
Norstrom, R.J.; Simon, M.; Muir, D.C.G.; Schweinsburg, R.E.
1988-09-01
Contamination of Canadian arctic and subarctic marine ecosystems by organochlorine (OC) compounds was measured by analysis of polar bear (Ursus maritimus) tissues collected from 12 zones between 1982 and 1984. PCB congeners (S-PCB), chlordanes, DDT and metabolites, chlorobenzenes (S-CBz), hexachlorocyclohexane isomers (S-HC-H), and dieldrin were identified by high-resolution gas chromatography-mass spectrometry. Nonachlor-III, a nonachlor isomer in technical chlordane, was positively identified for the first time as an environmental contaminant. S-PCB and S-CHLOR accounted for >80% of the total organochlorines in adipose tissue. Six PCB congeners constituted approximately 93% of S-PCB in polar bears. Levels of most OCs were lowest in the high Arctic, intermediate in Baffin Bay, and highest in Hudson Bay. Levels of ..cap alpha..-HCH were evaluated in zones influenced by surface runoff. Levels of S-CHLOR were four times higher and levels of the other OCs were two times higher in adipose tissue of bears from Hudson Bay and Baffin Bay in 1984 than in adipose tissue archived since 1969 from these areas; levels of S-DDT did not change.
In-Medium Parton Branching Beyond Eikonal Approximation
NASA Astrophysics Data System (ADS)
Apolinário, Liliana
2017-03-01
The description of the in-medium modifications of partonic showers has been at the forefront of current theoretical and experimental efforts in heavy-ion collisions. It provides a unique laboratory to extend our knowledge frontier of the theory of the strong interactions, and to assess the properties of the hot and dense medium (QGP) that is produced in ultra-relativistic heavy-ion collisions at RHIC and the LHC. The theory of jet quenching, a commonly used alias for the modifications of the parton branching resulting from the interactions with the QGP, has been significantly developed over the last years. Within a weak coupling approach, several elementary processes that build up the parton shower evolution, such as single gluon emissions, interference effects between successive emissions and corrections to radiative energy loss of massive quarks, have been addressed both at eikonal accuracy and beyond by taking into account the Brownian motion that high-energy particles experience when traversing a hot and dense medium. In this work, by using the setup of single gluon emission from a color correlated quark-antiquark pair in a singlet state (qbar{q} antenna), we calculate the in-medium gluon radiation spectrum beyond the eikonal approximation. The results show that we are able to factorize broadening effects from the modifications of the radiation process itself. This constitutes the final proof that a probabilistic picture of the parton shower evolution holds even in the presence of a QGP.
Chang, You Min; Lee, Junsu; Lee, Ju Han
2010-09-13
Proposed herein is an alternative photonic scheme for the generation of a doublet UWB pulse, which is based on the nonlinear polarization rotation of an elliptically polarized probe beam. The proposed scheme is a modified optical-fiber Kerr shutter that uses an elliptically polarized probe beam together with a linearly polarized control beam. Through theoretical analysis, it was shown that the optical-fiber-based Kerr shutter is capable of producing an ideal transfer function for the successful conversion of input Gaussian pulses into doublet pulses under special elliptical polarization states of the probe beam. An experimental verification was subsequently carried out to verify the working principle. Finally, the system performance of the generated UWB doublet pulses was assessed by propagating them over a 25-km-long standard single-mode fiber link, followed by wireless transmission. Error-free transmission was successfully achieved.
Investigation of Nuclear Partonic Structure. Final Report
Crawford, Henry J.; Engelage, J. M.
2016-08-30
Our research program had two primary goals during the period of this grant, to search for new and rare particles produced in high-energy nuclear collisions and to understand the internal structure of nuclear matter. We have developed electronics to pursue these goals at the Relativistic Heavy Ion Collider (RHIC) in the Solenoidal Tracker at RHIC (STAR) experiment and the AnDY experiment. Our results include discovery of the anti-hyper-triton, anti- ^{3}_{Λ-bar}H, which opened a new branch on the chart of the nuclides, and the anti-alpha, anti- ^{4}He, the heaviest form of anti-matter yet seen, as well as uncovering hints of gluon saturation in cold nuclear matter and observation of jets in polarized proton-proton collisions that will be used to probe orbital motion inside protons.
NASA Astrophysics Data System (ADS)
Bailey, Scott M.; Thomas, Gary E.; Hervig, Mark E.; Lumpe, Jerry D.; Randall, Cora E.; Carstens, Justin N.; Thurairajah, Brentha; Rusch, David W.; Russell, James M.; Gordley, Larry L.
2015-05-01
Nadir viewing observations of Polar Mesospheric Clouds (PMCs) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft are compared to Common Volume (CV), limb-viewing observations by the Solar Occultation For Ice Experiment (SOFIE) also on AIM. CIPS makes multiple observations of PMC-scattered UV sunlight from a given location at a variety of geometries and uses the variation of the radiance with scattering angle to determine a cloud albedo, particle size distribution, and Ice Water Content (IWC). SOFIE uses IR solar occultation in 16 channels (0.3-5 μm) to obtain altitude profiles of ice properties including the particle size distribution and IWC in addition to temperature, water vapor abundance, and other environmental parameters. CIPS and SOFIE made CV observations from 2007 to 2009. In order to compare the CV observations from the two instruments, SOFIE observations are used to predict the mean PMC properties observed by CIPS. Initial agreement is poor with SOFIE predicting particle size distributions with systematically smaller mean radii and a factor of two more albedo and IWC than observed by CIPS. We show that significantly improved agreement is obtained if the PMC ice is assumed to contain 0.5% meteoric smoke by mass, in agreement with previous studies. We show that the comparison is further improved if an adjustment is made in the CIPS data processing regarding the removal of Rayleigh scattered sunlight below the clouds. This change has an effect on the CV PMC, but is negligible for most of the observed clouds outside the CV. Finally, we examine the role of the assumed shape of the ice particle size distribution. Both experiments nominally assume the shape is Gaussian with a width parameter roughly half of the mean radius. We analyze modeled ice particle distributions and show that, for the column integrated ice distribution, Log-normal and Exponential distributions better represent the range
NASA Astrophysics Data System (ADS)
Liu, Wei; Chen, Yiqiao; Lu, Wentao; Moy, Aaron; Poelker, Matthew; Stutzman, Marcy; Zhang, Shukui
2016-12-01
Photocathodes that provide high electron-spin polarization (ESP) and high quantum efficiency (QE) can significantly enhance the physics capabilities of electron accelerators. We report record-level QE from a high-polarization strained GaAs/GaAsP superlattice photocathode fabricated with a Distributed Bragg Reflector (DBR). The DBR photocathode technique enhances the absorption of incident laser light thereby enhancing QE, but as literature suggests, it is very challenging to optimize all of the parameters associated with the fabrication of complicated photocathode structures composed of many distinct layers. Past reports of DBR photocathodes describe high polarization but typically QE of only ˜1%, which is comparable to QE of high polarization photocathodes grown without a DBR structure. This work describes a strained GaAs/GaAsP superlattice DBR photocathode exhibiting a high polarization of 84% and significantly enhanced QE of 6.4%.
Liu, Wei; Chen, Yiqiao; Lu, Wentao; ...
2016-12-19
Photocathodes that provide high polarization and high quantum efficiency (QE) can significantly enhance the physics capabilities of electron accelerators. We report record-level QE from a high-polarization strained GaAs/GaAsP superlattice photocathode fabricated with a Distributed Bragg Reflector (DBR). The DBR photocathode technique enhances the absorption of incident laser light thereby enhancing QE, but as literature suggests, it is very challenging to optimize all of the parameters associated with the fabrication of complicated photocathode structures composed of many distinct layers. Past reports of DBR photocathodes describe high polarization but typically QE of only ~ 1%, which is comparable to QE of highmore » polarization photocathodes grown without a DBR structure. As a result, this work describes a new strained GaAs/GaAsP superlattice DBR photocathode exhibiting polarization of 84% and QE of 6.4%.« less
Liu, Wei; Chen, Yiqiao; Lu, Wentao; Moy, Aaron; Poelker, Matthew; Stutzman, Marcy; Zhang, Shukui
2016-12-19
Photocathodes that provide high polarization and high quantum efficiency (QE) can significantly enhance the physics capabilities of electron accelerators. We report record-level QE from a high-polarization strained GaAs/GaAsP superlattice photocathode fabricated with a Distributed Bragg Reflector (DBR). The DBR photocathode technique enhances the absorption of incident laser light thereby enhancing QE, but as literature suggests, it is very challenging to optimize all of the parameters associated with the fabrication of complicated photocathode structures composed of many distinct layers. Past reports of DBR photocathodes describe high polarization but typically QE of only ~ 1%, which is comparable to QE of high polarization photocathodes grown without a DBR structure. As a result, this work describes a new strained GaAs/GaAsP superlattice DBR photocathode exhibiting polarization of 84% and QE of 6.4%.
Cornwall, C.; Titus, T.N.
2009-01-01
In the 1970s, Mariner and Viking observed features in the Mars northern polar region that were a few hundred kilometers in diameter with 20 fj,m brightness temperatures as low as 130 K (considerably below C02 ice sublimation temperatures). Over the past decade, studies have shown that these areas (commonly called "cold spots") are usually due to emissivity effects of frost deposits and occasionally to active C02 snowstorms. Three Mars years of Mars Global Surveyor Thermal Emission Spectrometer data were used to observe autumn and wintertime cold spot activity within the polar regions. Many cold spots formed on or near scarps of the perennial cap, probably induced by adiabatic cooling due to orographic lifting. These topographically associated cold spots were often smaller than those that were not associated with topography. We determined that initial grain sizes within the cold spots were on the order of a few millimeters, assuming the snow was uncontaminated by dust or water ice. On average, the half-life of the cold spots was 5 Julian days. The Mars global dust storm in 2001 significantly affected cold spot activity in the north polar region. Though overall perennial cap cold spot activity seemed unaffected, the distribution of cold spots did change by a decrease in the number of topographically associated cold spots and an increase in those not associated with topography. We propose that the global dust storm affected the processes that form cold spots and discuss how the global dust storm may have affected these processes. ?? 2009 by the American Geophysical Union.
NASA Astrophysics Data System (ADS)
Chang, Wen-Chen
2016-02-01
The observation of the violation of Lam-Tung relation in the πN Drell-Yan process triggered many theoretical speculations. The TMD Boer-Mulders functions characterizing the correlation of transverse momentum and transverse spin for partons in unpolarized hadrons could nicely account for the violation. The COMPASS experiment at CERN will measure the angular distributions of dimuons from the unpolarized Drell-Yan process over a wide kinematic region and study the beam particle dependence. Significant statistics is expected from a successful run in 2015 which will bring further understanding of the origin of the violation of Lam-Tung relation and of the partonic transverse spin structure of the nucleon.
NASA Astrophysics Data System (ADS)
Liu, Qing; Zhan, Yong-hong; Yang, Di; Zeng, Chang-e.
2014-11-01
In this paper, we try to find a model that can apply to predict the polarization characteristics of the targets on the ground correctly. In the first place, we give an introduction to several kinds of existing models which are divided into three categories: Empirical models are precise but occupy too much source of computer; Physical-based models can predict the phenomenon of reflection exactly but hardly get the final results; Semi-empirical models have both advantages mentioned above and avoid their disadvantages effectively. Then we make an analysis of the Priest-Germer (PG) pBRDF model, one of semi-empirical models, which is suitable for our study. The methods of parameters inversing and testing are proposed based on this model and the test system from which we can get enough data to verify the accuracy of the model is designed independently. At last, we make a simulation of the whole process of the parameters inversing based on PG pBRDF model. From the analysis of the simulation curves, we briefly know the direction we go in the following work to make an amendment.
Molecular motors are differentially distributed on Golgi membranes from polarized epithelial cells
1994-01-01
Microtubules (MT) are required for the efficient transport of membranes from the trans-Golgi and for transcytosis of vesicles from the basolateral membrane to the apical cytoplasm in polarized epithelia. MTs in these cells are primarily oriented with their plus ends basally near the Golgi and their minus-ends in the apical cytoplasm. Here we report that isolated Golgi and Golgi-enriched membranes from intestinal epithelial cells possess the actin based motor myosin-I, the MT minus- end-directed motor cytoplasmic dynein and its in vitro motility activator dynactin (p150/Glued). The Golgi can be separated into stacks, possessing features of the Golgi cisternae, and small membranes enriched in the trans-Golgi network marker TGN 38/41. Whereas myosin-I is present on all membranes in the Golgi fraction, dynein is present only on the small membrane fraction. Dynein, like myosin-I, is associated with membranes as a cytoplasmic peripheral membrane protein. Dynein and myosin-I coassociate with membranes that bind to MTs and cross-link actin filaments and MTs in a nucleotide-dependent manner. We propose that cytoplasmic dynein moves Golgi membranes along MTs to the cell cortex where myosin-I provides local delivery through the actin- rich cytoskeleton to the apical membrane. PMID:8045931
Gluons and the quark sea at high energies: distributions, polarization, tomography
Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.
2011-09-30
This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.
NASA Astrophysics Data System (ADS)
Warmate, Tamuno-Negiyeofori; Gamberg, Leonard; Prokudin, Alexei
2016-09-01
I have performed a phenomenological analysis of pion production data from Jefferson Laboratory in semi-inclusive deep inelastic scattering of electrons on unpolarized nucleons and deuterium using the transverse momentum dependent (TMD) parton model formalism. We parameterize the data in terms of TMD parton distribution functions that describe the three-dimensional (3-D) partonic structure of the nucleon. One of the main enigmas of data analysis is how to reliably estimate the errors of the parameters that describe some particular physical process. A common method is to use Hessian matrix or vary the delta chi-square of the corresponding fits to the data. In this particular project we use the so-called bootstrap method that is very robust for error estimation. This method has not been extensively used in the description of the TMD distributions that describe the 3-D nucleon structure. The reliable estimate of the errors and thus reliable predictions for future experiments is of great scientific interest. We are using Python and modern methods of data analysis in this project. The results of the project will be useful for understanding the effects of internal motion of quarks and gluons inside of the proton and will be reported in a forthcoming publication.
Zhu, Tongtong; Liu, Yingjun; Ding, Tao; Fu, Wai Yuen; Jarman, John; Ren, Christopher Xiang; Kumar, R. Vasant; Oliver, Rachel A.
2017-01-01
Distributed Bragg reflectors (DBRs) are essential components for the development of optoelectronic devices. For many device applications, it is highly desirable to achieve not only high reflectivity and low absorption, but also good conductivity to allow effective electrical injection of charges. Here, we demonstrate the wafer-scale fabrication of highly reflective and conductive non-polar gallium nitride (GaN) DBRs, consisting of perfectly lattice-matched non-polar (11–20) GaN and mesoporous GaN layers that are obtained by a facile one-step electrochemical etching method without any extra processing steps. The GaN/mesoporous GaN DBRs exhibit high peak reflectivities (>96%) across the entire visible spectrum and wide spectral stop-band widths (full-width at half-maximum >80 nm), while preserving the material quality and showing good electrical conductivity. Such mesoporous GaN DBRs thus provide a promising and scalable platform for high performance GaN-based optoelectronic, photonic, and quantum photonic devices. PMID:28345612
Dietzel, Erik; Anderson, Danielle E; Castan, Alexandre; von Messling, Veronika; Maisner, Andrea
2011-07-01
In paramyxoviruses, the matrix (M) protein mediates the interaction between the envelope and internal proteins during particle assembly and egress. In measles virus (MeV), M mutations, such as those found in subacute sclerosing panencephalitis (SSPE) strains, and differences in vaccine and wild-type M proteins can affect the strength of interaction with the envelope glycoproteins, assembly efficiency, and spread. However, the contribution of the M protein to the replication and pathogenesis of the closely related canine distemper virus (CDV) has not been characterized. To this end this, we generated a recombinant wild-type CDV carrying a vaccine strain M protein. The recombinant virus retained the parental growth phenotype in VerodogSLAMtag cells, but displayed an increased particle-to-infectivity ratio very similar to that of the vaccine strain, likely due to inefficient H protein incorporation. Even though infectious virus was released only from the apical surface, consistent with the release polarity of the wild-type CDV strain, envelope protein distribution in polarized epithelial cells reproduced the bipolar pattern seen in vaccine strain-infected cells. Most notably, the chimeric virus was completely attenuated in ferrets and caused only a mild and transient leukopenia, indicating that the differences in particle infectivity and envelope protein sorting mediated by the vaccine M protein contribute importantly to vaccine strain attenuation.
NASA Technical Reports Server (NTRS)
Fainberg, J.; Hoang, S.; Manning, R.
1985-01-01
An analysis is presented of the system response of a satellite receiver-antenna system to locate a radio source when the satellite is tilted on its axis. The satellite is spin stabilized but experiences a tilt due to either a mechanical misalignment or a shift in the electrical axis caused by parasitic currents in other spacecraft structures. The shorter the antenna, the more significant the effects. Numerical techniques are developed for obtaining the Stokes parameters and the angular parameters of a uniform conical source sensed by a linear antenna in order to derive the average power response of a synthesized dipole to a point on a distributed polarized source. Relative gains are calculated along the antenna at different angles to the source. The techniques are applied to sample ISEE-3 satellite data for Type III solar radio bursts which were sensed by an axial and an equatorial antenna. The two antennas permit localization of the source and quantification of the polarization and angular extent of the source. The resulting high precision in calculations of all three source parameters commends use of the model in analyses of data from the planned ULYSSES mission.
NASA Astrophysics Data System (ADS)
Zahran, M. A.; El-Shewy, E. K.; Abdelwahed, H. G.; Abdelwahed
2013-10-01
The nonlinear propagation of small but finite-amplitude dust-acoustic solitary waves in an unmagnetized, collisionless dusty plasma has been investigated. The fluid model is a generalization to the model of Mamun and Shukla to a more realistic space dusty plasma in different regions of space, viz., cometary tails, mesosphere, and Jupiter's magnetosphere, by considering a four-component dusty plasma consisting of the charged dusty plasma of opposite polarity, isothermal electrons and vortex-like ion distributions in the ambient plasma. A reductive perturbation method was employed to obtain a modified Korteweg-de Vries equation for the first-order potential. The effect of the presence of a positively charged dust fluid, the specific charge ratio μ, the temperature of the positively charged dust fluid, the ratio of constant temperature of free hot ions and the constant temperature of trapped ions, and ion temperature on the soliton properties and dusty grains energy are discussed.
Pisano, S.; Biselli, A.; Niccolai, S.; Seder, E.; Guidal, M.; Mirazita, M.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bosted, P.; Briscoe, B.; Brock, J.; Brooks, W. K.; Burkert, V. D.; Carlin, C.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crabb, D. G.; Crede, V.; D' Angelo, A.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garcon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hanretty, C.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, X.; Jo, H. S.; Joo, K.; Joosten, S.; Keith, C. D.; Keller, D.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacCormick, M.; MacGregor, Ian J. D.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Meyer, C. A.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Munoz Camacho, C.; Nadel-Turonski, P.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Phelps, W.; Phillips, J. J.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatie, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Skorodumina, I.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Turisini, M.; Ungaro, M.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.
2015-03-19
Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton e→p→e'p'γ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ^{14}NH_{3} target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. As a result, the measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the H and H~ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.
Measurements of global distributions of polar mesospheric clouds during 2005-2012 by MIPAS/Envisat
NASA Astrophysics Data System (ADS)
García-Comas, Maya; López-Puertas, Manuel; Funke, Bernd; Aythami Jurado-Navarro, Á.; Gardini, Angela; Stiller, Gabriele P.; von Clarmann, Thomas; Höpfner, Michael
2016-06-01
We have analysed MIPAS (Michelson Interferometer for Passive Atmopheric Sounding) infrared measurements of PMCs for the summer seasons in the Northern (NH) and Southern (SH) hemispheres from 2005 to 2012. Measurements of PMCs using this technique are very useful because they are sensitive to the total ice volume and independent of particle size. For the first time, MIPAS has provided coverage of the PMC total ice volume from midlatitudes to the poles. MIPAS measurements indicate the existence of a continuous layer of mesospheric ice, extending from about ˜ 81 km up to about 88-89 km on average and from the poles to about 50-60° in each hemisphere, increasing in concentration with proximity to the poles. We have found that the ice concentration is larger in the Northern Hemisphere than in the Southern Hemisphere. The ratio between the ice water content (IWC) in both hemispheres is also latitude-dependent, varying from a NH / SH ratio of 1.4 close to the poles to a factor of 2.1 around 60°. This also implies that PMCs extend to lower latitudes in the NH. A very clear feature of the MIPAS observations is that PMCs tend to be at higher altitudes with increasing distance from the polar region (in both hemispheres), particularly equatorwards of 70°, and that they are about 1 km higher in the SH than in the NH. The difference between the mean altitude of the PMC layer and the mesopause altitude increases towards the poles and is larger in the NH than in the SH. The PMC layers are denser and wider when the frost-point temperature occurs at lower altitudes. The layered water vapour structure caused by sequestration and sublimation of PMCs is present at latitudes northwards of 70° N and more pronounced towards the pole. Finally, MIPAS observations have also shown a clear impact of the migrating diurnal tide on the diurnal variation of the PMC volume ice density.
Four-jet production in single- and double-parton scattering within high-energy factorization
NASA Astrophysics Data System (ADS)
Kutak, Krzysztof; Maciula, Rafal; Serino, Mirko; Szczurek, Antoni; van Hameren, Andreas
2016-04-01
We perform a first study of 4-jet production in a complete high-energy factorization (HEF) framework. We include and discuss contributions from both single-parton scattering (SPS) and double-parton scattering (DPS). The calculations are performed for kinematical situations relevant for two experimental measurements (ATLAS and CMS) at the LHC. We compare our results to those reported by the ATLAS and CMS collaborations for different sets of kinematical cuts. The results of the HEF approach are compared with their counterparts for collinear factorization. For symmetric cuts the DPS HEF result is considerably smaller than the one obtained with collinear factorization. The mechanism leading to this difference is of kinematical nature. We conclude that an analysis of inclusive 4-jet production with asymmetric p T -cuts below 50 GeV would be useful to enhance the DPS contribution relative to the SPS contribution. In contrast to the collinear approach, the HEF approach nicely describes the distribution of the Δ S variable, which involves all four jets and their angular correlations.
Large-pT production of D mesons at the LHCb in the parton Reggeization approach
NASA Astrophysics Data System (ADS)
Karpishkov, A. V.; Saleev, V. A.; Shipilova, A. V.
2016-12-01
The production of D mesons in proton-proton collisions at the LHCb detector is studied. We consider the single production of D0/D¯0, D±, D*±, and Ds± mesons and correlation spectra in the production of D D ¯ and D D pairs at the √{S }=7 TeV and √{S }=13 TeV . In case of the single D -meson production we calculate differential cross sections over transverse momentum pT while in the pair D D ¯ , D D -meson production the cross sections are calculated over the azimuthal angle difference Δ φ , rapidity difference Δ y , invariant mass of the pair M and over the pT of the one meson from a pair. The cross sections are obtained at the leading order of the parton Reggeization approach using Kimber-Martin-Ryskin unintegrated parton distribution functions in a proton. To describe the D -meson production we use universal scale-dependent c -quark and gluon fragmentation functions fitted to e+e- annihilation data from CERN LEP1. Our predictions find a good agreement with the LHCb Collaboration data within uncertainties and without free parameters.
Polarised Parton Densities from the Fits to the Deep Inelastic Spin Asymmetries on Nucleons
NASA Astrophysics Data System (ADS)
Bartelski, Jan; Tatur, Stanislaw
2001-07-01
We have updated our next to leading order QCD fit for polarised parton densities [S. Tatur, J. Bartelski, M. Kurzela, Acta Phys. Pol. B31, 647 (2000)] using recent experimental data on the deep inelastic spin asymmetries on nucleons. Our distributions have functional form inspired by the unpolarised ones given by MRST (Martin, Roberts, Stirling and Thorne) fit. In addition to usually used data sample (averaged over variable Q2 for the same value of x variable) we have also considered the points with the same x and different Q2. Our fits to both groups of data give very similar results with substantial antiquark contribution in the measured region of x. In the first case we get rather small (Δ G=0.31) gluon polarisation. For the non averaged data the best fit is obtained when gluon contribution vanishes at Q2=1GeV2. Our new parametrisation of parton densities and additional experimental data taken into account do not change much our previous results.
Nuclear effects on tetraquark production by double parton scattering
NASA Astrophysics Data System (ADS)
Carvalho, F.; Navarra, F. S.
2017-03-01
In this work we study the nuclear effects in exotic meson production. We estimate the total cross section as a function of the energy for pPb scattering using a version of the color evaporation model (CEM) adapted to Double Parton Scattering (DPS). We fond that the cross section grows significantly with the atomic number, indicating that the hypothesis of tetraquark states can be tested in pA collisions at LHC.
Mamun, A A; Shukla, P K
2009-09-01
Effects of the nonthermal distribution of electrons as well as the polarity of the net dust-charge number density on nonplanar (viz. cylindrical and spherical) dust-ion-acoustic solitary waves (DIASWs) are investigated by employing the reductive perturbation method. It is found that the basic features of the DIASWs are significantly modified by the effects of nonthermal electron distribution, polarity of net dust-charge number density, and nonplanar geometry. The implications of our results in some space and laboratory dusty plasma environments are briefly discussed.
NASA Technical Reports Server (NTRS)
Pommereau, J. P.; Piquard, J.
1994-01-01
A light, relatively cheap and easy to operate balloonborne UV-visible spectrometer was designed for investigating ozone photochemistry in the Arctic winter. The instrument was flown 11 times during the European Arctic Stratospheric Ozone Experiment (EASOE) in winter 1991-92 in Northern Scandinavia. The first simultaneous measurements of vertical distributions of aerosols, PSC's, O3, NO2 and OClO inside the vortex during flight no. 6 on 16 January, in cold conditions are reported, which show that nitrogen oxides were almost absent (lower than 100 ppt) in the stratosphere below 22 km, while a layer of relatively large OClO concentration (15 ppt) was present at the altitude of the minimum temperature.
Yu, Zhangjun; Yang, Jun; Yuan, Yonggui; Li, Chuang; Liang, Shuai; Hou, Lu; Peng, Feng; Wu, Bing; Zhang, Jianzhong; Liu, Zhihai; Yuan, Libo
2016-01-25
A white light temporal interferometric technique for measurement of the quasi-distributed birefringence dispersion (BD) in a polarization maintain (PM) device with high accuracy based on weighted least square (WLS) method is presented. It is verified theoretically and experimentally that the accuracy of WLS method and the conventional ordinary least square (OLS) method both are proportional to the signal-to-noise ratio (SNR) of interferogram, whereas the WLS method holds a higher scaling factor because it is more suitable for heteroscedastic model that has unequal error variance. The experiment results show a repeatability of ~4.6 × 10(-5) ps/nm @ 1550 nm with WLS method for 100 sets of data, and ~4.3 × 10(-4) ps/nm with OLS method, for an interferogram with SNR of 30 dB. Besides, WLS method without iterative operation is carried out by using power spectrum of interferogram as weight value. The feasibility of this technique is demonstrated by distinguishing the quasi-distributed BD of every part for a packaged Y-waveguide with two 1m-long PM pigtails.
Adare, A.
2016-03-23
In this article, we present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from W^{±}/Z decays, produced in longitudinally polarized p+p collisions at center of mass energies of √s=500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the W-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb^{-1}, which exceeds previous PHENIX published results by a factor of more than 27. In addition, these high Q^{2} data probe the parton structure of the proton at W mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken x value of roughly M_{W}/√s=0.16.
Methods comparison, transport and distribution of polar herbicides in the Baltic Sea.
Skeff, Wael; Orlikowska, Anna; Schulz-Bull, Detlef E
2017-01-30
Two LC-MS/MS methods including different sample preparation and quantitative processes showed a good agreement for analysis of the herbicides MCPA, mecoprop, isoproturon, bentazon and chloridazon, and the metabolite chloridazon-methyl-desphenyl (CMD) in estuarine waters. Due to different sensitivity of the methods only one could be used to analyze marine samples. The transport of these compounds to the Baltic Sea via ten German estuaries and their distribution between coastal water and sediments was studied. The results showed that all selected compounds can be transported to the Baltic Sea (0.9-747ng/L). Chloridazon, bentazon, isoproturon and CMD were detected (0.9-8.9ng/L) in the coastal waters and chloridazon and isorproturon in the sediments (5-136pg/g d.w.). Levels of contaminants in the sediments could be influenced by the total organic carbon content. Concentrations observed in the Baltic Sea are most likely not high enough to cause acute effects, but long term effect studies are strongly recommended.
Ito, Yosuke; Sato, Daichi; Kamada, Keigo; Kobayashi, Tetsuo
2016-07-11
An optically pumped K-Rb hybrid atomic magnetometer can be a useful tool for biomagnetic measurements due to the high spatial homogeneity of its sensor property inside a cell. However, because the property varies depending on the densities of potassium and rubidium atoms, optimization of the densities is essential. In this study, by using the Bloch equations of K and Rb and considering the spatial distribution of the spin polarization, we confirmed that the calculation results of spin polarization behavior are in good agreement with the experimental data. Using our model, we calculated the spatial distribution of the spin polarization and found that the optimal density of K atoms is 3 × 10^{19} m^{-3} and the optimal density ratio is n_{K}/n_{Rb} ~ 400 to maximize the output signal and enhance spatial homogeneity of the sensor property.
Lattice study of the Boer-Mulders transverse momentum distribution in the pion
Engelhardt, Michael; Musch, Bernhard; Haegler, Philipp; Negele, John; Schaefer, Andreas
2014-11-01
The Boer-Mulders transverse momentum-dependent parton distribution (TMD) characterizes polarized quark transverse momentum in an unpolarized hadron. Techniques previously developed for lattice calculations of nucleon TMDs are applied to the pion. These techniques are based on the evaluation of matrix elements of quark bilocal operators containing a staple-shaped Wilson connection. Results for the Boer-Mulders transverse momentum shift in the pion, obtained at a pion mass of mπ=518MeV, are presented and compared to corresponding results in the nucleon.
Triple Parton Scatterings in High-Energy Proton-Proton Collisions
NASA Astrophysics Data System (ADS)
d'Enterria, David; Snigirev, Alexander M.
2017-03-01
A generic expression to compute triple parton scattering cross sections in high-energy proton-proton (p p ) collisions is presented as a function of the corresponding single parton cross sections and the transverse parton profile of the proton encoded in an effective parameter σeff,TPS . The value of σeff,TPS is closely related to the similar effective cross section that characterizes double parton scatterings, and amounts to σeff,TPS=12.5 ±4.5 mb . Estimates for triple charm (c c ¯) and bottom (b b ¯) production in p p collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order perturbative calculations for single c c ¯ , b b ¯ cross sections. At √{s }≈100 TeV , about 15% of the p p collisions produce three c c ¯ pairs from three different parton-parton scatterings.
Prompt-photon plus jet associated photoproduction at HERA in the parton Reggeization approach
NASA Astrophysics Data System (ADS)
Kniehl, B. A.; Nefedov, M. A.; Saleev, V. A.
2014-06-01
We study the photoproduction of isolated prompt photons associated with hadron jets in the framework of the parton Reggeization approach. The cross section distributions in the transverse energies and pseudorapidities of the prompt photon and the jet as well as the azimuthal-decorrelation variables measured by the H1 and ZEUS collaborations at DESY HERA are nicely described by our predictions. The main improvements with respect to previous studies in the kT-factorization framework include the application of the Reggeized-quark formalism, the generation of exactly gauge-invariant amplitudes with off-shell initial-state quarks, and the exact treatment of the γR→γg box contribution with off-shell initial-state gluons.
NASA Astrophysics Data System (ADS)
Yuan, Kai-Jun; Bandrauk, André D.
2013-10-01
Photoionization of an aligned molecular ion H? has been investigated with two colour circularly polarized ultrashort UV laser pulses by numerically solving the corresponding time dependent Schrödinger equation. Photoelectron angular distributions (PADs) in molecular above threshold ionization (MATI) exhibit: (i) asymmetry resulting from interference of coherent electron wave packets from multiple pathway ionization, which depends critically on the relative carrier envelope phase (CEP) ? between the two colour laser pulses and photoelectron kinetic energies; (ii) rotation with respect to the molecular symmetry axes due to effects of the nonspherical two center Coulomb potential. Such features are described by multi-photon perturbative theoretical ionization models. The ionization probability is functions of both the CEP ? and the angle ? between the electron emission and the molecular axis. The influence of pulse intensity and ellipticity on PADs in MATI is also investigated. It is found that the asymmetry depends on the pulse intensity whereas the rotation angle is shown to be sensitive to the pulse ellipticity, both reflecting the orientation dependence of molecular ionization probabilities.
Fouka, M.; Ouichaoui, S. E-mail: souichaoui@usthb.dz
2011-12-10
We have derived asymptotic forms for the degree of polarization of the optically thin synchrotron and for synchrotron self-absorption (SSA) spectra assuming a power-law particle distribution of the form N({gamma}) {approx} {gamma}{sup -p} with {gamma}{sub 1} < {gamma} < {gamma}{sub 2}, especially for a finite high-energy limit, {gamma}{sub 2}, in the case of an arbitrary pitch angle. The new results inferred concern more especially the high-frequency range x >> {eta}{sup 2} with parameter {eta} = {gamma}{sub 2}/{gamma}{sub 1}. The calculated SSA spectra concern instantaneous photon emission where cooling effects are not considered. They have been obtained by also ignoring likely effects such as Comptonization, pair creation and annihilation, as well as magnetic photon splitting. To that aim, in addition to the two usual absorption frequencies, a third possible one has been derived and expressed in terms of the Lambert W function based on the analytical asymptotic form of the absorption coefficient, {alpha}{sub {nu}}, for the high-frequency range {nu} >> {nu}{sub 2} (with {nu}{sub 2} the synchrotron frequency corresponding to {gamma}{sub 2}). We have shown that the latter frequency may not have realistic applications in astrophysics, except in the case of an adequate set of parameters allowing one to neglect Comptonization effects. More detailed calculations and discussions are presented.
NASA Astrophysics Data System (ADS)
Fouka, M.; Ouichaoui, S.
2011-12-01
We have derived asymptotic forms for the degree of polarization of the optically thin synchrotron and for synchrotron self-absorption (SSA) spectra assuming a power-law particle distribution of the form N(γ) ~ γ-p with γ1 < γ < γ2, especially for a finite high-energy limit, γ2, in the case of an arbitrary pitch angle. The new results inferred concern more especially the high-frequency range x Gt η2 with parameter η = γ2/γ1. The calculated SSA spectra concern instantaneous photon emission where cooling effects are not considered. They have been obtained by also ignoring likely effects such as Comptonization, pair creation and annihilation, as well as magnetic photon splitting. To that aim, in addition to the two usual absorption frequencies, a third possible one has been derived and expressed in terms of the Lambert W function based on the analytical asymptotic form of the absorption coefficient, αν, for the high-frequency range ν Gt ν2 (with ν2 the synchrotron frequency corresponding to γ2). We have shown that the latter frequency may not have realistic applications in astrophysics, except in the case of an adequate set of parameters allowing one to neglect Comptonization effects. More detailed calculations and discussions are presented.
NASA Astrophysics Data System (ADS)
Wang, J.; Zhang, C.; Zhu, C.; Wei, Y.; Dong, H.; Liu, W.
2011-12-01
Core isoprenoidal glycerol dibiphytanyl dlycerol tetraethers (C-iGDGTs) are the most widespread archaeal lipids in sediments and water, and have been used to construct a molecular proxy, TEX86, for studying past sea surface temperatures. However, recent analyses of intact polar (IP)-iGDGTs that are indicative of living archaea suggest that IP-iGDGTs produced in situ in marine sediments may subsequently convert IP-iGDGTs to C-iGDGTs after the cell death, thus compromising the validity of TEX86 for paleoclimate research. To help address this question, we investigated the distribution and abundance of IP- and C- iGDGTs in suspended particulates and surface sediments from the lower Pearl River and estuary. Our results show a strong positive correlation between the C- and P-iGDGTs pools, especially the iGDGT-0 (R2 = 0.786, p<0.001), iGDGT-1 (R2 = 0.920, p<0.001), and crenarchaeol (R2 = 0.871, p<0.001), suggesting that aquatic archaeal lipids are mostly derived from in situ production in the river water and/or sediments, and a minor fraction of these lipids are terrestrially-sourced. Methanogens (belonging to Euryarchaeota) may be an important source of iGDGTs in water and sediments of Pearl River estuary, which may further complicate the use of TEX86 that is based on planktonic Crenarchaeota.
Beaumier, Michael J.
2016-08-01
This thesis discusses the process of extracting the longitudinal asymmetry, A$W±\\atop{L}$ describing W → μ production in forward kinematic regimes. This asymmetry is used to constrain our understanding of the polarized parton distribution functions characterizing $\\bar{u}$ and $\\bar{d}$ sea quarks in the proton. This asymmetry will be used to constrain the overall contribution of the sea-quarks to the total proton spin. The asymmetry is evaluated over the pseudorapidity range of the PHENIX Muon Arms, 2.1 < |η| 2.6, for longitudinally polarized proton-proton collisions at 510 GeV √s. In particular, I will discuss the statistical methods used to characterize real muonic W decays and the various background processes is presented, including a discussion of likelihood event selection and the Extended Unbinned Maximum Likelihood t. These statistical methods serve estimate the yields of W muonic decays, which are used to calculate the longitudinal asymmetry.
Neufeld, Richard B.; Vitev, Ivan M.
2011-01-01
We derive the distribution of energy and momentumtransmitted from a primary fast parton and its medium-induced bremsstrahlung gluons to a thermalized quark-gluon plasma. Our calculation takes into account the important and thus far neglected effects of quantum interference between the resulting color currents. We use our result to obtain the rate at which energy is absorbed by the medium as a function of time and find that the rate is modified by the quantum interference between the primary parton and secondary gluons. This Landau-Pomeranchuk-Migdal type interference persists for time scales relevant to heavy ion phenomenology. We further couple the newly derived source of energy and momentum deposition to linearized hydrodynamics to obtain the bulk medium response to realistic parton propagation and splitting in the quark-gluon plasma. We find that because of the characteristic large angle in-medium gluon emission and the multiple sources of energy deposition in a parton shower, formation of well defined Mach cones by energetic jets in heavy ion reactions is not likely.
LHAPDF6: parton density access in the LHC precision era
NASA Astrophysics Data System (ADS)
Buckley, Andy; Ferrando, James; Lloyd, Stephen; Nordström, Karl; Page, Ben; Rüfenacht, Martin; Schönherr, Marek; Watt, Graeme
2015-03-01
The Fortran LHAPDF library has been a long-term workhorse in particle physics, providing standardised access to parton density functions for experimental and phenomenological purposes alike, following on from the venerable PDFLIB package. During Run 1 of the LHC, however, several fundamental limitations in LHAPDF's design have became deeply problematic, restricting the usability of the library for important physics-study procedures and providing dangerous avenues by which to silently obtain incorrect results. In this paper we present the LHAPDF 6 library, a ground-up re-engineering of the PDFLIB/LHAPDF paradigm for PDF access which removes all limits on use of concurrent PDF sets, massively reduces static memory requirements, offers improved CPU performance, and fixes fundamental bugs in multi-set access to PDF metadata. The new design, restricted for now to interpolated PDFs, uses centralised numerical routines and a powerful cascading metadata system to decouple software releases from provision of new PDF data and allow completely general parton content. More than 200 PDF sets have been migrated from LHAPDF 5 to the new universal data format, via a stringent quality control procedure. LHAPDF 6 is supported by many Monte Carlo generators and other physics programs, in some cases via a full set of compatibility routines, and is recommended for the demanding PDF access needs of LHC Run 2 and beyond.
Moments of Isovector Quark Distributions in Lattice QCD
W. Detmold; Wally Melnitchouk; A.W. Thomas
2002-06-01
We investigate the connection of lattice calculations of moments of isovector parton distributions to the physical regime through extrapolations in the quark mass. We consider the one pion loop renormalization of the nucleon matrix elements of the corresponding operators and thereby develop formulae with which to extrapolate the moments of the unpolarized, helicity and transversity distributions. There formulae are consistent with chiral perturbation theory in the chiral limit and incorporate the correct heavy quark limits. In the polarized cases, the inclusion of intermediate states involving the Delta isobar is found to be very important. The results of our extrapolations are in general agreement with the phenomenological values of these moments where they are known, and for the first time we perform an extrapolation of the low moments of the isovector transversity distribution which is consistent with chiral symmetry.
Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L
2014-01-01
BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.
NASA Astrophysics Data System (ADS)
Ilyushin, Yaroslaw; Kutuza, Boris
Observations and mapping of the upwelling thermal radiation of the Earth is the very promising remote sensing technique for the global monitoring of the weather and precipitations. For reliable interpretation of the observation data, numerical model of the microwave radiative transfer in the precipitating atmosphere is necessary. In the present work, numerical simulations of thermal microwave radiation in the rain have been performed at three wavelengths (3, 8 and 22 mm). Radiative properties of the rain have been simulated using public accessible T-matrix codes (Mishchenko, Moroz) for non-spherical particles of fixed orientation and realistic raindrop size distributions (Marshall-Palmer) within the range of rain intensity 1-100 mm/h. Thermal radiation of infinite flat slab medium and isolated rain cell of kilometer size has been simulated with finite difference scheme for the vectorial radiative transfer equation (VRTE) in dichroic scattering medium. Principal role of cell structure of the rain field in the formation of angular and spatial distribution of the intensity and polarization of the upwelling thermal radiation has been established. Possible approaches to interpretation of satellite data are also discussed. It is necessary that spatial resolution of microwave radiometers be less than rain cell size. At the present time the resolution is approximately 15 km. It can be considerably improved, for example by two-dimensional synthetic aperture millimeter-wave radiometric interferometer for measuring full-component Stokes vector of emission from hydrometeors. The estimates show that in millimeter band it is possible to develop such equipment with spatial resolution of the order of 1-2 km, which is significantly less than the size of rain cell, with sensitivity 0.3-0.5 K. Under this condition the second Stokes parameter may by successfully measured and may be used for investigation of precipitation regions. Y-shaped phased array antenna is the most promising to
NASA Astrophysics Data System (ADS)
Vigdor, Steven
2006-10-01
Hard-scattering collisions of transversely polarized protons may be preferentially initiated by partons with transverse momentum (kT) directed toward one side of the plane formed by the proton's momentum and spin vectors [1]. Parton orbital angular momentum within the proton is a prerequisite for this so-called Sivers effect. We report the first measurement of the Sivers asymmetry in collisions of transversely polarized proton beams, using di-jet production data acquired with the STAR detector during the 2006 RHIC run. A non-zero Sivers function would be manifested directly by a spin-dependent change in the distribution of the azimuthal opening angle between the two reconstructed jets [2]. We present a preliminary analysis reconstructing the jet thrust axes only from the electromagnetic calorimeter component of the jet energies, recorded online at trigger level for a sample of ˜ 3 million di-jet events. By selecting subsets of events within particular phase space regions, we can emphasize quark- or gluon-dominated Sivers functions. In addition to experimental results, we present model simulations that demonstrate the correlations among various measures of the Sivers asymmetries, and their sensitivity to the shape of the underlying kT distribution. [1] D. Sivers, Phys. Rev. D41, 83 (1990) and Phys. Rev. D43, 261 (1991). [2] D. Boer and W. Vogelsang, Phys. Rev. D69, 094025 (2004).
NASA Astrophysics Data System (ADS)
Weber, G.; Bräuning, H.; Surzhykov, A.; Brandau, C.; Fritzsche, S.; Geyer, S.; Grisenti, R. E.; Hagmann, S.; Hahn, C.; Hess, R.; Hess, S.; Kozhuharov, C.; Kühnel, M.; Märtin, R.; Petridis, N.; Spillmann, U.; Trotsenko, S.; Winters, D. F. A.; Stöhlker, Th
2015-07-01
By applying novel-type position sensitive x-ray detectors as Compton polarimeters we recently performed a study of the linear polarization of Lyman-{{α }1} radiation following radiative electron capture into initially bare uranium ions. It was found that a model-independent determination of the ratio of the E1 and M2 transition amplitudes, and consequently of the corresponding transition rates, is feasible by combining the linear polarization data with a measurement of the angular distribution of the emitted radiation. In this work a detailed description of the underlying experimental technique for combined measurements of the linear polarization and the angular distribution of characteristic transitions in high-Z ions is presented. Special emphasis is given to the application of two, two-dimensional position-sensitive x-ray detectors for Compton polarimetry of hard x-rays. Moreover, we demonstrate the polarimeter efficiency of such detector systems can be significantly improved if events, where the charge is spread over neighboring segments, are reconstructed to be used in the polarization analysis.
Peel, Andrew D; Averof, Michalis
2010-11-01
The localization of maternal mRNAs during oogenesis plays a central role in axial specification in some insects. Here we describe a polar body-associated asymmetry in maternal transcript distribution in pre-blastoderm eggs of the beetle Tribolium castaneum. Since the position of the polar body marks the future dorsal side of the embryo, we have investigated whether this asymmetry in mRNA distribution plays a role in dorsal-ventral axis specification. Whilst our results suggest polar body-associated transcripts do not play a significant role in specifying the DV axis, at least during early embryogenesis, we do find that the polar body is closely associated with a cortical microtubule network (CMN), which may play a role in the localization of transcripts during oogenesis. Transcripts of the gene T.c.pangolin co-localize with the CMN at the time of their anterior localization during oogenesis and their anterior localization is disrupted by the microtubule-depolymerizing agent colcemid.
Carrete, Jesús; Méndez-Morales, Trinidad; Cabeza, Óscar; Lynden-Bell, Ruth M; Gallego, Luis J; Varela, Luis M
2012-05-24
In this work, we used molecular dynamics simulations to analyze in detail the spatial distributions of the different constituents in mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate with three polar molecular species: water and two alcohols of different chain lengths (methanol and ethanol). In particular, we report results regarding the influence of the chosen species and its concentration on the formation of ionic and molecular clusters over the whole miscibility range, as well as on the angular distribution of polar molecules around the anion and the cation in these systems. Both analyses showed that addition of a molecular species breaks down the polar network of the pure ionic liquid in clusters whose mean size decreases progressively as more molecules are added. At very high concentrations of the molecular species, the ions are found to be isolated in mixtures with water and methanol, but they tend to form pairs in ethanol. In mixtures with water we identified large clusters that form a water network at very high water concentrations, while at low water concentrations polar molecules tend to form smaller aggregates. In contrast, in mixtures with alkanols there is no evidence of the formation of large alcohol clusters at any concentration. Spatial order in alcohol was also studied by means of the Kirkwood G factor, reaching the conclusion that the angular correlations which appear in pure alcohols due to dipole interactions are destroyed by the ionic liquid, even when present only in tiny amounts.
NASA Astrophysics Data System (ADS)
Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Aben, R.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. 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H.; Smestad, L.; Smiesko, J.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Song, H. Y.; Sood, A.; Sopczak, A.; Sopko, V.; Sorin, V.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; Denis, R. D. St.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tan, K. G.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teischinger, F. A.; Teixeira-Dias, P.; Temming, K. K.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turgeman, D.; Turra, R.; Tuts, P. M.; Tyndel, M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valdes Santurio, E.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; Van Der Deijl, P. C.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, W.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, M. D.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wolf, T. M. H.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, M.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zwalinski, L.
2016-11-01
Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of √{s}=7 TeV are analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of 37 .3 pb-1, collected with the ATLAS detector at the LHC. The contribution of hard double-parton scattering to the production of four-jet events is extracted using an artificial neural network, assuming that hard double-parton scattering can be approximated by an uncorrelated overlaying of dijet events. For events containing at least four jets with transverse momentum p T ≥ 20 GeV and pseudorapidity | η| ≤ 4 .4, and at least one having p T ≥ 42 .5 GeV, the contribution of hard double-parton scattering is estimated to be f DPS = 0.092 - 0.011 + 0.005 (stat.) - 0.037 + 0.033 (syst.). After combining this measurement with those of the inclusive dijet and four-jet cross-sections in the appropriate phase space regions, the effective cross-section, σ eff , was determined to be σ eff = 14. 9 - 1.0 + 1.2 (stat.) - 3.8 + 5.1 (syst.) mb. This result is consistent within the quoted uncertainties with previous measurements of σ eff , performed at centre-of-mass energies between 63 GeV and 8 TeV using various final states, and it corresponds to 21 - 6 + 7 % of the total inelastic cross-section measured at √{s}=7 TeV. The distributions of the observables sensitive to the contribution of hard double-parton scattering, corrected for detector effects, are also provided. [Figure not available: see fulltext.
NASA Astrophysics Data System (ADS)
Birenbaum, Axiel Yaël; Ederer, Claude
2016-02-01
This work explores the impact of in-plane bi-axial (epitaxial) strain on the cation distribution and electric polarization of the Aurivillius-phase compound Bi5FeTi3O15 using first-principles electronic structure calculations. Our calculations indicate that the site preference of the Fe3+ cation can be controlled via epitaxial strain. Tensile strain enhances the preference for the inner sites within the perovskite-like layers of the Aurivillius-phase structure, whereas compressive strain favors occupation of the outer sites, i.e., the sites close to the Bi2O2 layer. Controlling the distribution of the magnetic cations offers the possibility to control magnetic order in this magnetically dilute system. Furthermore, the magnitude of the electric polarization is strongly strain-dependent, increasing under tensile strain and decreasing under compressive strain. We find strongly anomalous Born effective charges, both of the Bi3+ and the Ti4+ cations.
Gladysiewicz, M. Janicki, L.; Kudrawiec, R.; Siekacz, M.; Cywinski, G.
2015-12-28
Electric field distribution in N-polar GaN(channel)/AlGaN/GaN(buffer) heterostructures was studied theoretically by solving Schrodinger and Poisson equations in a self-consistent manner for various boundary conditions and comparing results of these calculations with experimental data, i.e., measurements of electric field in GaN(channel) and AlGaN layers by electromodulation spectroscopy. A very good agreement between theoretical calculations and experimental data has been found for the Fermi-level located at ∼0.3 eV below the conduction band at N-polar GaN surface. With this surface boundary condition, the electric field distribution and two dimensional electron gas concentration are determined for GaN(channel)/AlGaN/GaN(buffer) heterostructures of various thicknesses of GaN(channel) and AlGaN layers.
Lie, E.; Bernhoft, A.; Riget, F.; Belikov, Stanislav; Boltunov, Andrei N.; Derocher, A.E.; Garner, G.W.; Wiig, O.; Skaare, J.U.
2003-01-01
Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, ??-HCH, ??-HCH and p,p???-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of ??- and ??-HCH. The lowest ??-HCH concentration was found in bears from Kara Sea. In all the bears, ???HCHs was dominated by ??-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p???-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research. ?? 2002 Elsevier Science B.V. All rights reserved.
NASA Technical Reports Server (NTRS)
Craven, P. D.; Gary, G. A.
1972-01-01
The Mie theory of light scattering by spheres was used to calculate the scattered intensity functions resulting from single scattering in a polydispersed collection of spheres. The distribution used behaves according to the inverse fourth power law; graphs and tables for the angular dependence of the intensity and polarization for this law are given. The effects of the particle size range and the integration increment are investigated.
Double parton effects for jets with large rapidity separation
Szczurek, Antoni; Cisek, Anna; Maciuła, Rafal
2015-04-10
We discuss production of four jets pp → jjjjX with at least two jets with large rapidity separation in proton-proton collisions at the LHC through the mechanism of double-parton scattering (DPS). The cross section is calculated in a factorizaed approximation. Each hard subprocess is calculated in LO collinear approximation. The LO pQCD calculations are shown to give a reasonably good descritption of CMS and ATLAS data on inclusive jet production. It is shown that relative contribution of DPS is growing with increasing rapidity distance between the most remote jets, center-of-mass energy and with decreasing (mini)jet transverse momenta. We show also result for angular azimuthal dijet correlations calculated in the framework of k{sub t} -factorization approximation.
PEPSI — a Monte Carlo generator for polarized leptoproduction
NASA Astrophysics Data System (ADS)
Mankiewicz, L.; Schäfer, A.; Veltri, M.
1992-09-01
We describe PEPSI (Polarized Electron Proton Scattering Interactions), a Monte Carlo program for polarized deep inelastic leptoproduction mediated by electromagnetic interaction, and explain how to use it. The code is a modification of the LEPTO 4.3 Lund Monte Carlo for unpolarized scattering. The hard virtual gamma-parton scattering is generated according to the polarization-dependent QCD cross-section of the first order in α S. PEPSI requires the standard polarization-independent JETSET routines to simulate the fragmentation into final hadrons.
Measurement of deeply virtual compton scattering with a polarized-proton target.
Chen, S; Avakian, H; Burkert, V D; Eugenio, P; Adams, G; Amarian, M; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Bonner, B E; Bouchigny, S; Boiarinov, S; Bosted, P; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Cazes, A; Cole, P L; Collins, P; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Crede, V; Cummings, J P; DeMasi, R; DeVita, R; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Forest, T A; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gonenc, A; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hafidi, K; Hakobyan, H; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Juengst, H G; Keith, C; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klusman, M; Kossov, M; Kramer, L H; Kubarovsky, V; Kuhn, J; Kuhn, S E; Kuleshov, S V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Li, Ji; Lima, A C S; Livingston, K; Lu, H; Lukashin, K; MacCormick, M; Markov, N; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Morand, L; Morrow, S A; Moteabbed, M; Mueller, J; Mutchler, G S; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Natasha, N; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Popa, I; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabian, Y G; Shaw, J; Shvedunov, N V; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Thoma, U; Tkabladze, A; Tkachenko, S; Todor, L; Tur, C; Ungaro, M; Vanderhaeghen, M; Vineyard, M F; Vlassov, A V; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J; Zhao, B; Zhao, Z
2006-08-18
The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H.
NASA Astrophysics Data System (ADS)
Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Abdou Ahmed, Marwan
2016-04-01
The efficient generation of a cylindrically (radially or azimuthally) polarized LG01 mode was investigated using a ring-shaped pumping distribution in a high-power Yb:YAG thin-disk laser setup. This was realized by implementing a 300 mm long customized fused silica fiber capillary in the pump beam path of the pumping optics of a thin-disk laser. Furthermore, a grating waveguide mirror based on the leaky-mode coupling mechanism was used as one of the cavity end mirrors to allow sufficient reduction of the reflectivity of the polarization state to be suppressed in the resonator. In order to achieve efficient laser operation, an optimized mode overlap between the ring-shaped pump spot and the excited first order Laguerre-Gaussian doughnut mode is required. This was investigated theoretically by analyzing the intensity distribution generated by different fiber geometries using a commercially raytracing software (Zemax). The output power, polarization state and efficiency of the emitted laser beam were compared to that obtained with a standard flattop pumping distribution. In particular, the thermal behavior of the disk was investigated since the excessive fluorescence caused by the non-saturated excitation in the center of the homogeneously pumped disk leads to a strong heating of the crystal. This considerable heating source is avoided in the case of the ring-shaped pumping and a reduction of the temperature increase on the disk surface of about 21% (at 280 W of pump power) was observed. This should allow higher pump power densities without increasing the risk of damaging the disk or distorting the polarization purity. With a laser efficiency of 41.2% to be as high as in the case of the flattop pumping, a maximum output power of 107 W was measured.
Jet Hadronization via Recombination of Parton Showers in Vacuum and in Medium
NASA Astrophysics Data System (ADS)
Fries, Rainer J.; Han, Kyongchol; Ko, Che Ming
2016-12-01
We introduce a hadronization algorithm for jet parton showers based on a hybrid approach involving recombination of quarks and fragmentation of strings. The algorithm can be applied to parton showers from a shower Monte Carlo generator at the end of their perturbative evolution. The algorithm forces gluon decays and then evaluates the recombination probabilities for quark-antiquark pairs into mesons and (anti)quark triplets into (anti)baryons. We employ a Wigner phase space formulation based on the assumption of harmonic oscillator wave functions for stable hadrons and resonances. Partons too isolated in phase space to find recombination partners are connected by QCD strings to other quarks. Fragmentation of those remnant strings and the decay of all hadron resonances complete the hadronization process. We find that our model applied to parton showers from the PYTHIA Monte Carlo event generator leads to results very similar to pure Lund string fragmentation. We suggest that our algorithm can be readily generalized to jets embedded in quark-gluon plasma by adding sampled thermal partons from the phase transition hypersurface. The recombination of thermal partons and shower partons leads to an enhancement of pions and protons at intermediate momentum at both RHIC and LHC.
Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François
2015-04-20
During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs.
Chatrchyan, S; Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hartl, C; Hörmann, N; Hrubec, J; Jeitler, M; Kiesenhofer, W; Knünz, V; Krammer, M; Krätschmer, I; Liko, D; Mikulec, I; Rabady, D; Rahbaran, B; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Treberer-Treberspurg, W; Waltenberger, W; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Alderweireldt, S; Bansal, M; Bansal, S; Cornelis, T; De Wolf, E A; Janssen, X; Knutsson, A; Luyckx, S; Mucibello, L; Ochesanu, S; Roland, B; Rougny, R; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Van Spilbeeck, A; Blekman, F; Blyweert, S; D'Hondt, J; Heracleous, N; Kalogeropoulos, A; Keaveney, J; Kim, T J; Lowette, S; Maes, M; Olbrechts, A; Strom, D; Tavernier, S; Van Doninck, W; Van Mulders, P; Van Onsem, G P; Villella, I; Caillol, C; Clerbaux, B; De Lentdecker, G; Favart, L; Gay, A P R; Hreus, T; Léonard, A; Marage, P E; Mohammadi, A; Perniè, L; 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Hall-Wilton, R; Herndon, M; Hervé, A; Klabbers, P; Klukas, J; Lanaro, A; Loveless, R; Mohapatra, A; Ojalvo, I; Perry, T; Pierro, G A; Polese, G; Ross, I; Sarangi, T; Savin, A; Smith, W H
2014-05-09
Spin correlations and polarization in the top quark-antiquark system are measured using dilepton final states produced in pp collisions at the LHC at sqrt[s]=7 TeV. The data correspond to an integrated luminosity of 5.0 fb(-1) collected with the CMS detector. The measurements are performed using events with two oppositely charged leptons (electrons or muons), a significant imbalance in transverse momentum, and two or more jets, where at least one of the jets is identified as originating from a b quark. The spin correlations and polarization are measured through asymmetries in angular distributions of the two selected leptons, unfolded to the parton level. All measurements are found to be in agreement with predictions of the standard model.
Polarized light ions and spectator nucleon tagging at EIC
Guzey, Vadim; Higinbotham, Dougas W.; Hyde, Charles; Nadel-Turonski, Pawel A.; Park, Kijun; Sargsian, Misak M.; Strikman, Mark; Weiss, Christian
2014-10-01
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ll 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < p(R) < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.
Virtual photon structure functions and the parton content of the electron
Drees, M. ); Godbole, R.M. )
1994-09-01
We point out that in processes involving the parton content of the photon the usual effective photon approximation should be modified. The reason is that the parton content of virtual photons is logarithmically suppressed compared to real photons. We describe this suppression using several simple, physically motivated [ital Ansa]$[ital uml---tze]. Although the parton content of the electron in general no longer factorizes into an electron flux function and a photon structure function, it can still be expressed as a single integral. Numerical examples are given for the [ital e][sup +][ital e][sup [minus
NASA Astrophysics Data System (ADS)
Planck Collaboration; Aghanim, N.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Burigana, C.; Calabrese, E.; Cardoso, J.-F.; Chiang, H. C.; Colombo, L. P. L.; Combet, C.; Comis, B.; Crill, B. P.; Curto, A.; Cuttaia, F.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Dusini, S.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; Ghosh, T.; Giard, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Herranz, D.; Hivon, E.; Huang, Z.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Levrier, F.; Liguori, M.; Lilje, P. B.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Naselsky, P.; Nørgaard-Nielsen, H. U.; Oxborrow, C. A.; Pagano, L.; Paoletti, D.; Partridge, B.; Patrizii, L.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Plaszczynski, S.; Polenta, G.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, C.; Sirri, G.; Stanco, L.; Suur-Uski, A.-S.; Tauber, J. A.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Vansyngel, F.; Van Tent, F.; Vielva, P.; Wandelt, B. D.; Wehus, I. K.; Zacchei, A.; Zonca, A.
2017-02-01
The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce decorrelations between 217 and 353 GHz data similar to the values we observe in the data.
Bowman, J S; Larose, C; Vogel, T M; Deming, J W
2013-08-01
Frost flowers are highly saline ice structures that grow on the surface of young sea ice, a spatially extensive environment of increasing importance in the Arctic Ocean. In a previous study, we reported organic components of frost flowers in the form of elevated levels of bacteria and exopolymers relative to underlying ice. Here, DNA was extracted from frost flowers and young sea ice, collected in springtime from a frozen lead offshore of Barrow, Alaska, to identify bacteria in these understudied environments. Evaluation of the distribution of 16S rRNA genes via four methods (microarray analysis, T-RFLP, clone library and shotgun metagenomic sequencing) indicated distinctive bacterial assemblages between the two environments, with frost flowers appearing to select for Rhizobiales. A phylogenetic placement approach, used to evaluate the distribution of similar Rhizobiales sequences in other polar marine studies, indicated that some of the observed strains represent widely distributed members of the marine rare biosphere in both the Arctic and Antarctic.
Single perturbative splitting diagrams in double parton scattering
NASA Astrophysics Data System (ADS)
Gaunt, Jonathan R.
2013-01-01
We present a detailed study of a specific class of graph that can potentially contribute to the proton-proton double parton scattering (DPS) cross section. These are the `2v1' or `single perturbative splitting' graphs, in which two `nonperturbatively generated' ladders interact with two ladders that have been generated via a perturbative 1 → 2 branching process. Using a detailed calculation, we confirm the result written down originally by Ryskin and Snigirev — namely, that the 2v1 graphs in which the two nonperturbatively generated ladders do not interact with one another do contribute to the leading order proton-proton DPS cross section, albeit with a different geometrical prefactor to the one that applies to the `2v2'/`zero perturbative splitting' graphs. We then show that 2v1 graphs in which the `nonperturbatively generated' ladders exchange partons with one another also contribute to the leading order proton-proton DPS cross section, provided that this `crosstalk' occurs at a lower scale than the 1 → 2 branching on the other side of the graph. Due to the preference in the 2v1 graphs for the x value at which the branching occurs, and crosstalk ceases, to be very much larger than the x values at the hard scale, the effect of crosstalk interactions is likely to be a decrease in the 2v1 cross section except at exceedingly small x values (≲ 10-6). At moderate x values ≃ 10-3 -10-2, the x value at the splitting is in the region ≃ 10-1 where PDFs do not change much with scale, and the effect of crosstalk interactions is likely to be small. We give an explicit formula for the contribution from the 2v1 graphs to the DPS cross section, and combine this with a suggestion that we made in a previous publication, that the `double perturbative splitting'/`1v1' graphs should be completely removed from the DPS cross section, to obtain a formula for the DPS cross section. It is pointed out that there are two potentially concerning features in this equation, that
Distribution of the K-corona over the polar regions of the solar disk: 1965-1983. Technical note
Fisher, R.; Seagraves, P.
1984-01-01
The goal of this technical note is to present a set of synoptic observations from the Mauna Loa series of K-coronameters in polar projection format. The initial motivation for the production of these plots was the desire to present data that would be useful in the study of the evolution of high-latitude coronal streamers over the solar cycles 20 and 21. It now seems likely that there will be other uses for these data. Possibly the variation of coronal hole area over sunspot cycle can be extracted from the data presented below, and it is anticipated that the POLES plots of the north and south polar regions will provide an interesting adjunct data set for the upcoming ISPM mission, now scheduled for the minimum of the present sunspot cycle. Only east limb data have been used for this project. This choice was dictated by the amount of disk space available at Mauna Loa for the Mk-I and Mk-II data. A synoptic record of both limbs is presently kept for Mk-III data, and the routine used for the polar plot may be applied to either the east limb or west limb data from this current version of the instrument.
Tutt, Lee; Revelli, Joseph F
2008-03-01
The angular distribution of radiation emitted from organic electroluminescent diodes fabricated on substrates with wavelength-scale gratings was measured using an optical Fourier transform instrument. A simple geometrical model is derived that specifies the polar angle of the exiting photon as a function of the azimuth angle, the grating pitch, the wavelength of light, and the effective index of the refraction of the light emitted by the fluorescing excitons. The radiation pattern of the extracted light is shown to fit that predicted by the model if one assumes that it comes from surface plasmon polaritons and bound TE waveguide modes.
Automated parton-shower variations in pythia 8
NASA Astrophysics Data System (ADS)
Mrenna, S.; Skands, P.
2016-10-01
In the era of precision physics measurements at the LHC, efficient and exhaustive estimations of theoretical uncertainties play an increasingly crucial role. In the context of Monte Carlo (MC) event generators, the estimation of such uncertainties traditionally requires independent MC runs for each variation, for a linear increase in total run time. In this work, we report on an automated evaluation of the dominant (renormalization-scale and nonsingular) perturbative uncertainties in the pythia 8 event generator, with only a modest computational overhead. Each generated event is accompanied by a vector of alternative weights (one for each uncertainty variation), with each set separately preserving the total cross section. Explicit scale-compensating terms can be included, reflecting known coefficients of higher-order splitting terms and reducing the effect of the variations. The formalism also allows for the enhancement of rare partonic splittings, such as g →b b ¯ and q →q γ , to obtain weighted samples enriched in these splittings while preserving the correct physical Sudakov factors.
Automated parton-shower variations in PYTHIA 8
Mrenna, S.; Skands, P.
2016-10-03
In the era of precision physics measurements at the LHC, efficient and exhaustive estimations of theoretical uncertainties play an increasingly crucial role. In the context of Monte Carlo (MC) event generators, the estimation of such uncertainties traditionally requires independent MC runs for each variation, for a linear increase in total run time. In this work, we report on an automated evaluation of the dominant (renormalization-scale and nonsingular) perturbative uncertainties in the pythia 8 event generator, with only a modest computational overhead. Each generated event is accompanied by a vector of alternative weights (one for each uncertainty variation), with each set separately preserving the total cross section. Explicit scale-compensating terms can be included, reflecting known coefficients of higher-order splitting terms and reducing the effect of the variations. In conclusion, the formalism also allows for the enhancement of rare partonic splittings, such as g→bb¯ and q→qγ, to obtain weighted samples enriched in these splittings while preserving the correct physical Sudakov factors.
Automated parton-shower variations in PYTHIA 8
Mrenna, S.; Skands, P.
2016-10-03
In the era of precision physics measurements at the LHC, efficient and exhaustive estimations of theoretical uncertainties play an increasingly crucial role. In the context of Monte Carlo (MC) event generators, the estimation of such uncertainties traditionally requires independent MC runs for each variation, for a linear increase in total run time. In this work, we report on an automated evaluation of the dominant (renormalization-scale and nonsingular) perturbative uncertainties in the pythia 8 event generator, with only a modest computational overhead. Each generated event is accompanied by a vector of alternative weights (one for each uncertainty variation), with each set separatelymore » preserving the total cross section. Explicit scale-compensating terms can be included, reflecting known coefficients of higher-order splitting terms and reducing the effect of the variations. In conclusion, the formalism also allows for the enhancement of rare partonic splittings, such as g→bb¯ and q→qγ, to obtain weighted samples enriched in these splittings while preserving the correct physical Sudakov factors.« less
Energy flow along the medium-induced parton cascade
Blaizot, J.-P.
2016-05-15
We discuss the dynamics of parton cascades that develop in dense QCD matter, and contrast their properties with those of similar cascades of gluon radiation in vacuum. We argue that such cascades belong to two distinct classes that are characterized respectively by an increasing or a constant (or decreasing) branching rate along the cascade. In the former class, of which the BDMPS, medium-induced, cascade constitutes a typical example, it takes a finite time to transport a finite amount of energy to very soft quanta, while this time is essentially infinite in the latter case, to which the DGLAP cascade belongs. The medium induced cascade is accompanied by a constant flow of energy towards arbitrary soft modes, leading eventually to the accumulation of the initial energy of the leading particle at zero energy. It also exhibits scaling properties akin to wave turbulence. These properties do not show up in the cascade that develops in vacuum. There, the energy accumulates in the spectrum at smaller and smaller energy as the cascade develops, but the energy never flows all the way down to zero energy. Our analysis suggests that the way the energy is shared among the offsprings of a splitting gluon has little impact on the qualitative properties of the cascades, provided the kernel that governs the splittings is not too singular.
Letter of Intent for a Drell-Yan Experiment with a Polarized Proton Target
Geesaman, D.; Reimer, P.; Brown, C.; Christian, D.; Diefenthaler, M.; Peng, J. -C.; Chang, W. -C.; Chen, Y. -C.; Sawada, S.; Chang, T. -H.; Huang, J.; Jiang, X.; Leitch, M.; Klein, A.; Liu, K.; Liu, M.; McGaughey, P.; Beise, E.; Nakahara, K.; Aidala, C.; Lorenzon, W.; Raymond, R.; Badman, T.; Long, E.; Slifer, K.; Zielinski, R.; Guo, R. -S.; Goto, Y.; El Fassi, L.; Myers, K.; Ransome, R.; Tadepalli, A.; Tice, B.; Chen, J. -P.; Nakano, K.; Shibata, T. -A.; Crabb, D.; Day, D.; Keller, D.; Rondon, O.
2014-01-01
It is well known that the proton is a spin-1/2 particle, but how the constituents (quarks and gluons) assemble to this quantized spin is still a mystery. There is a worldwide effort to map out the individual contributions to the proton spin. It is established that the quark spins contribute around 30%, while the gluon intrinsic angular momentum is still under active investigation at the Relativistic Heavy Ion Collider. Fully resolving the proton spin puzzle requires information on the orbital angular momentum (OAM) of both quarks and gluons. Recent studies have shown that the so-called transverse momentum-dependent parton distribution functions (TMDs) can inform us about the OAM of the partons. One of the most important TMDs, and the main focus of this LOI, is the so-called Sivers function. To summarize, we propose to make the first measurement of the Sivers function of sea quarks, which is expected to be non-zero if the sea quarks contribute orbital angular momentum to the proton spin, as expected from the pion cloud model, which also partially explains the E866 results. Thus, we will be able to deduce whether or not sea quark orbital motion contributes significantly to the proton spin. Specifically, we will determine the contribution from the anti-up quarks, with Bjorken-x in the range of ~ 0.1 to 0.5. Drell-Yan production off a polarized proton target has never been measured, and is complementary to the recently approved (stage-1) experiment E1027 at Fermilab, which will measure the Sivers function of the valence quarks using a polarized proton beam on an unpolarized proton target. If the measured sea quark Sivers function is non-zero, we will also determine its sign.
Transverse momentum distributions inside the nucleon from lattice QCD
Musch, B. U.; Haegler, Ph.; Negele, J. W.; Schaefer, A.
2011-07-15
We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.
Transverse momentum distributions inside the nucleon from lattice QCD
Bernhard Musch, Philipp Haegler, John Negele, Andreas Schaefer
2011-07-01
We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.
NASA Technical Reports Server (NTRS)
Dye, James E.; Baumgardner, D.; Gandrud, B. W.; Kawa, S. R.; Kelly, K. K.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Gary, B. L.
1992-01-01
The paper uses particle size and volume measurements obtained with the forward scattering spectrometer probe model 300 during January and February 1989 in the Airborne Arctic Stratospheric Experiment to investigate processes important in the formation and growth of polar stratospheric cloud (PSC) particles. It is suggested on the basis of comparisons of the observations with expected sulfuric acid droplet deliquescence that in the Arctic a major fraction of the sulfuric acid droplets remain liquid until temperatures at least as low as 193 K. It is proposed that homogeneous freezing of the sulfuric acid droplets might occur near 190 K and might play a role in the formation of PSCs.
Teng, Lei; Zhang, Hongying; Dong, Yongkang; Zhou, Dengwang; Jiang, Taofei; Gao, Wei; Lu, Zhiwei; Chen, Liang; Bao, Xiaoyi
2016-09-15
A temperature-compensated distributed hydrostatic pressure sensor based on Brillouin dynamic gratings (BDGs) is proposed and demonstrated experimentally for the first time, to the best of our knowledge. The principle is to measure the hydrostatic pressure induced birefringence changes through exciting and probing the BDGs in a thin-diameter pure silica polarization-maintaining photonic crystal fiber. The temperature cross-talk to the hydrostatic pressure sensing can be compensated through measuring the temperature-induced Brillouin frequency shift (BFS) changes using Brillouin optical time-domain analysis. A distributed measurement of hydrostatic pressure is demonstrated experimentally using a 4-m sensing fiber, which has a high sensitivity, with a maximum measurement error less than 0.03 MPa at a 20-cm spatial resolution.
Harrison, James F
2009-07-28
We calculated the dipole moment function for the ground (3)Sigma(-)(m(S) = +1) state of the open shell molecules, NF, NCl, and NBr, and analyzed it in terms of the charge and spin distribution and the induced atomic dipoles using the Hirshfeld partitioning of the electron density. The smallest dipole moment (0.026ea(0)) obtains with NF, in which the atoms have the largest difference in electronegativity, while the dipole moments in NCl and NBr are 0.441ea(0) and 0.506ea(0), respectively. All dipoles have the N(-)X(+) polarity. In the sigma system alpha spin electrons flow from N to the halogen while beta spin electrons flow in the opposite direction and interestingly from both the sigma and the pi systems of the halogen to the sigma system of N. In NF the number of beta spins lost by F is essentially equal to the number of alpha spins gained and the atomic charges are essentially 0. The small dipole in NF is the result of a slight imbalance in the induced atomic dipoles. For NCl and NBr the halogen loses more beta spins than it gains alpha spins resulting in the polarity N(-)X(+). It is interesting that at equilibrium N gained electrons in the pi system while the halogen lost pi electrons relative to the separated atoms. This however is not back donation in the usual sense because the electrons gained by N have alpha spin while those lost by the halogen have beta spin. Detailed examination of the spin flow shows that the excess alpha electrons in the pi system of N come from an intra-atomic transfer from the N sigma system. The induced atomic dipole moments essentially cancel at all internuclear separations and the polarity of the dipole moment accurately reflects the molecular charge distribution.
Xie, Shangran; Pang, Meng; Bao, Xiaoyi; Chen, Liang
2012-03-12
The dependence of Brillouin linewidth and peak frequency on lightwave state of polarization (SOP) due to fiber inhomogeneity in single mode fiber (SMF) is investigated by using Brillouin optical time domain analysis (BOTDA) system. Theoretical analysis shows fiber inhomogeneity leads to fiber birefringence and sound velocity variation, both of which can cause the broadening and asymmetry of the Brillouin gain spectrum (BGS) and thus contribute to the variation of Brillouin linewidth and peak frequency with lightwave SOP. Due to fiber inhomogeneity both in lateral profile and longitudinal direction, the measured BGS is the superposition of several spectrum components with different peak frequencies within the interaction length. When pump or probe SOP changes, both the peak Brillouin gain and the overlapping area of the optical and acoustic mode profile that determine the peak efficiency of each spectrum component vary within the interaction length, which further changes the linewidth and peak frequency of the superimposed BGS. The SOP dependence of Brillouin linewidth and peak frequency was experimentally demonstrated and quantified by measuring the spectrum asymmetric factor and fitting obtained effective peak frequency respectively via BOTDA system on standard step-index SMF-28 fiber. Experimental results show that on this fiber the Brillouin spectrum asymmetric factor and effective peak frequency vary in the range of 2% and 0.06MHz respectively over distance with orthogonal probe input SOPs. Experimental results also show that in distributed fiber Brillouin sensing, polarization scrambler (PS) can be used to reduce the SOP dependence of Brillouin linewidth and peak frequency caused by fiber inhomogeneity in lateral profile, however it maintains the effects caused by fiber inhomogeneity in longitudinal direction. In the case of non-ideal polarization scrambling using practical PS, the fluctuation of effective Brillouin peak frequency caused by fiber inhomogeneity
NASA Astrophysics Data System (ADS)
Ma, Kun; Dong, Chen-Zhong; Xie, Lu-You; Ding, Xiao-Bin; Qu, Yi-Zhi
2014-05-01
The inner-shell 2p3/2 photoionization and the subsequent decay of Mg-like Fe14+, Cd36+, W62+ and U80+ ions are studied theoretically within the multiconfiguration Dirac—Fock method and the density matrix theory. Special attention is paid to exploring the influence of the non-dipole terms which arise from the multipole expansion of the electron-photon interaction in the photoionization process. The results show that the non-dipole contribution to the total cross section, the magnetic sublevels cross section of the photoionization process, the degree of linear polarization and angular distribution of the subsequent characteristic x-ray radiation become more important with the increase of photons energy and atomic nuclear Z. Especially for the cross section and the degree of linear polarization, the non-dipole contribution arrives at 50% for U80+ at four time energy threshold units. However, for the angular distribution, the maximum contribution does not exceed 4%, even for U80+ ions.
NASA Astrophysics Data System (ADS)
Das, Ashok K.; Hsiao, Pai-Yi
2015-02-01
Langevin dynamics simulations are performed to study the response of charged dendrimers in alternating current electric fields in 3:1 salt solutions. Time evolutions of molecular size show breathing characteristics which take saw-tooth-like patterns in square-wave electric fields and undulated sine-function ones in sine-wave fields. Detailed study reveals how the dendrimer and condensed ions oscillate in the electric fields, which result in polarization of the molecule. To effect a significant deformation of the dendrimer, the applied field amplitude must be larger than some critical strength Ecrit and the field frequency smaller than a threshold fcrit. The response behavior is characterized by two relaxation times in square-wave fields, both of which decrease linearly with the strong field strength larger than Ecrit. In sine-wave fields, the molecular size exhibits interesting hysteretic behavior in plotting the curves with the field variation. A Maxwell-Wagner type polarization theory is derived and proved by simulations, which connects fcrit with the strength of the applied electric field.
Huang, J.; Allada, K.; Dutta, C.; ...
2012-01-01
We report the first measurement of the double-spin asymmetry ALT for charged pion electroproduction in semi-inclusive deep inelastic electron scattering on a transversely polarized 3He target. The kinematics focused on the valence quark region, 0.16 < x < 0.35 with 1.4 < Q2 < 2.7 GeV2. The corresponding neutron ALT asymmetries were extracted from the measured 3He asymmetries and proton/3He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g1Tq and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for π- production on 3Hemore » and the neutron, while our π+ asymmetries are consistent with zero.« less
Huang, J; Allada, K; Dutta, C; Katich, J; Qian, X; Wang, Y; Zhang, Y; Aniol, K; Annand, J R M; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J-P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P A M; Dutta, D; El Fassi, L; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; Lerose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H-J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z-E; Michaels, R; Moffit, B; Muñoz Camacho, C; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A J R; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Sirca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L-G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y-W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X
2012-02-03
We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.16
NASA Astrophysics Data System (ADS)
Legue, Valerie; Pereda, Veronica; Gerard, Joelle; Eche, Brigitte; Gasset, Gilbert; Chaput, Didier
Plants are the ability to sense and to re-orient their growth in response to gravity. In roots, specialized sensory cells (called statocytes) perceive signal gravity and are the only cells that exhibit structural polarity with respect to gravity providing interactions with starch-containing plastids (amyloplasts) and the cortical endoplasmic reticulum (ER). Upon root reorientation, a displacement of amyloplasts is observed and is accompanied with a change in direct amyloplast-ER direct interaction in root cap cells. Even if amyloplasts are widely considered as gravity sensor, there is no clear evidence that a change in amyloplasts-ER interactions could lead to a transduction gravity signal. Previous space experiments clearly showed that amyloplasts inter-action with ER are not necessary to lead to a root re-orientation, suggesting that amyloplasts displacement mediate transduction events through cytoskeleton reorganisation and calcium-dependant pathways. The objective of the space experiment called PolCa is to dissect the effect of change in amyloplasts-ER interactions on calcium dependant pathways. Space conditions provide a unique opportunity to provide a change of structural polarity in statocytes without a gravistimulation. PolCa experiment has been conducted using Brassica napus seedlings, which submitted four different conditions: continuously on 1 g centrifuge or continuously in micrograv-ity conditions. Some seedlings germinated on centrifuge have been transferred during 10 min in microgravity conditions, leading to a loss of amyloplast-ER interactions through amyloplasts displacement. Others seedlings germinated in microgravity conditions have been transferred on centrifuge during 10 min. In this situation, we observed a return of amyloplasts-ER interactions. We analysed the localisation of free calcium after chemical fixation and calcium precipitation using potassium pyroantimonate in these four situations. The observation of calcium precipita-tions with
Greaves, Alana K; Letcher, Robert J; Sonne, Christian; Dietz, Rune
2013-03-01
The present study investigated the comparative accumulation of perfluoroalkyl acids (PFAAs) in eight brain regions of polar bears (Ursus maritimus, n = 19) collected in 2006 from Scoresby Sound, East Greenland. The PFAAs studied were perfluoroalkyl carboxylates (PFCAs, C(6) -C(15) chain lengths) and sulfonates (C(4) , C(6) , C(8) , and C(10) chain lengths) as well as selected precursors including perfluorooctane sulfonamide. On a wet-weight basis, blood-brain barrier transport of PFAAs occurred for all brain regions, although inner regions of the brain closer to incoming blood flow (pons/medulla, thalamus, and hypothalamus) contained consistently higher PFAA concentrations compared to outer brain regions (cerebellum, striatum, and frontal, occipital, and temporal cortices). For pons/medulla, thalamus, and hypothalamus, the most concentrated PFAAs were perfluorooctane sulfonate (PFOS), ranging from 47 to 58 ng/g wet weight, and perfluorotridecanoic acid, ranging from 43 to 49 ng/g wet weight. However, PFOS and the longer-chain PFCAs (C(10) -C(15) ) were significantly (p < 0.002) positively correlated with lipid content for all brain regions. Lipid-normalized PFOS and PFCA (C(10) -C(15) ) concentrations were not significantly (p > 0.05) different among brain regions. The burden of the sum of PFCAs, perfluoroalkyl sulfonates, and perfluorooctane sulfonamide in the brain (average mass, 392 g) was estimated to be 46 µg. The present study demonstrates that both PFCAs and perfluoroalkyl sulfonates cross the blood-brain barrier in polar bears and that wet-weight concentrations are brain region-specific.
Geomorphology of Triton's polar materials
NASA Technical Reports Server (NTRS)
Croft, Steven K.
1993-01-01
One of Triton's most debated puzzles is the nature, distribution, and transport of its atmospheric volatiles. The full potential of constraints provided by detailed observations of the morphology and distribution of the polar deposits has not been realized. The objective of this study is characterization of the morphology, distribution, stratigraphy, and geologic setting of Triton's polar materials.
Precision Polarized SIDIS Experiments in Hall-A at 12 GeV Jlab
Allada, Kalyan C.; Sulkosky, Vincent A.
2012-06-01
Single (SSA) and double spin asymmetries (DSA) in semi-inclusive DIS reactions using polarized nucleon targets provide a powerful method to probe transverse momentum dependent parton distribution functions (TMDs). The Jefferson Lab 12 GeV upgrade will provide a unique opportunity to perform such precision measurements and to map out these multi-dimensional PDFs. Future plans for performing these measurements in Hall-A using the Solenoidal Large Intensity Device (SoLID) and polarized proton and 3He (neutron) targets are discussed. The high luminosities from these targets and the large acceptance of the SoLID spectrometer will allow for a 4-dimensional (x, Q^2, z, P_T ) mapping of SSA and DSA. The full azimuthal angular coverage is necessary to untangle various angular moments and thereby reduce the systematic uncertainties. These experiments will provide the most precise data to extract transversity (h1), Sivers (f_1T) and Worm-gear (g_1T and h_1L) distributions of u and d-quarks and provide comprehensive information on the correlation between quark angular momentum and the nucleon's spin.
A 3D simulation of the early winter distribution of reactive chlorine in the north polar vortex
NASA Technical Reports Server (NTRS)
Douglass, A.; Rood, R.; Waters, J.; Froidevaux, L.; Read, W.; Elson, L.; Geller, M.; Chi, Y.; Cerniglia, M.; Steenrod, S.
1993-01-01
Early in December 1991, high values of ClO are seen by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite at latitudes south of areas of temperatures cold enough to form polar stratospheric clouds (PSCs). A 3D simulation shows that the heterogeneous conversion of chlorine reservoirs to reactive chlorine on the surfaces of PSCs (processing) takes place at high latitudes. Often the processed air must be transported to lower latitudes, where the reactive chlorine is photochemically converted to ClO, to be observed by MLS. In this simulation, one incidence of cold temperatures is associated with an anticyclone, and a second with a cyclone. The transport of processed air associated with the anticyclone is marked by shearing; a decrease in the maximum of the processed air is accompanied by growth of the area influenced by the processing. In contrast, the air processed in the cyclonic event spreads more slowly. This shows that transport and shearing is a crucial element to the evolution of reactive chlorine associated with a processing event. In particular, transport and shearing, as well as photochemical processes, can cause variations in observed ClO.
Mulari, Mika T. K.; Büki, Kálmán G.; Vihko, Pirkko; Härkönen, Pirkko L.; Väänänen, H. Kalervo
2012-01-01
Osteoclasts are bone-resorbing multinucleated cells that undergo drastic changes in their polarization due to heavy vesicular trafficking during the resorption cycle. These events require the precise orchestration of membrane traffic in order to maintain the unique characteristics of the different membrane domains in osteoclasts. Rab proteins are small GTPases involved in regulation of most, if not all, steps of vesicle trafficking. The investigators studied RAB genes in human osteoclasts and found that at least 26 RABs were expressed in osteoclasts. Out of these, RAB13 gene expression was highly upregulated during differentiation of human peripheral blood monocytic cells into osteoclasts. To study its possible function in osteoclasts, the investigators performed immunolocalization studies for Rab13 and various known markers of osteoclast vesicular trafficking. Rab13 localized to small vesicular structures at the superior parts of the osteoclast between the trans-Golgi network and basolateral membrane domain. Rab13 localization suggests that it is not involved in endocytosis or transcytosis of bone degradation products. In addition, Rab13 did not associate with early endosomes or recycling endosomes labeled with EEA1 or TRITC-conjugated transferrin, respectively. Its involvement in glucose transporter traffic was excluded as well. It is suggested that Rab13 is associated with a putative secretory function in osteoclasts. PMID:22562557
NASA Astrophysics Data System (ADS)
Sears, Amy E.; McGwire, Bradford S.; Roizman, Bernard
1991-06-01
Herpes simplex virus 1 attaches to at least two cell surface receptors. In polarized epithelial (Madin-Darby canine kidney; MDCK) cells one receptor is located in the apical surface and attachment to the cells requires the presence of glycoprotein C in the virus. The second receptor is located in the basal surface and does not require the presence of glycoprotein C. Exposure of MDCK cells at either the apical or basal surface to wild-type virus yields plaques and viral products whereas infection by a glycoprotein C-negative mutant yields identical results only after exposure of MDCK cells to virus at the basal surface. Multiple receptors for viral entry into cells expand the host range of the virus. The observation that glycoprotein C-negative mutants are infectious in many nonpolarized cell lines suggests that cells in culture may express more than one receptor and explains why genes that specify the viral proteins that recognize redundant receptors, like glycoprotein C, are expendable.
NASA Astrophysics Data System (ADS)
Yuan, Kai-Jun; Chelkowski, Szczepan; Bandrauk, André D.
2014-10-01
We present molecular photoelectron angular distributions (MPADs) in multi-photon ionization processes by circularly polarized attosecond UV laser pulses. Simulations are performed on the single electron aligned molecular ion H_2^+ by solving corresponding 3D time-dependent Schrödinger equations. Numerical results of molecular above threshold ionization (MATI) show that rotations of MPADs with respect to the molecular and polarization axes depend on pulse intensities and photoelectron kinetic energies. We attribute the rotation to Γ, the difference between parallel and perpendicular ionization probabilities. It is found that in a resonant ionization process, the rotation angle is also a function of the symmetry of intermediate electronic states. The coherent population transfer between the initial and the resonant electronic states is controlled by pulse intensities. Such dependence of rotations on the pulse intensity is absent in Rydberg resonant ionizations as well as in MATI at large energy photons ℏω > Ip, where ω is angular frequency of photons and Ip is the molecular ionization potential. We describe these processes by a multi-photon perturbation theory model. Effects of molecular alignment and pulse ellipticities on rotations are investigated, confirming the essence of the ionization parameter Γ in rotations of MPADs.
NASA Astrophysics Data System (ADS)
Wachter, Paul; Höppner, Kathrin; Jacobeit, Jucundus; Diedrich, Erhard
2015-04-01
West Antarctica and the Antarctic Peninsula are in the focus of current studies on a changing environment and climate of the polar regions. A recently founded Junior Researchers Group at the German Aerospace Center (DLR) is studying changing processes in cryosphere and atmosphere above the Antarctic Peninsula. It is the aim of the group to make use of long-term remote sensing data sets of the land and ice surfaces and the atmosphere in order to characterize environmental changes in this highly sensitive region. One of the PhD projects focuses on the investigation of the 3D temperature distribution patterns above the Antarctic Peninsula. Temperature data sets ranging from MODIS land surface temperatures up to middle atmosphere data of AURA/MLS will be evaluated over the last approx. 12 years. This 3-dimensional view allows comprehensive investigations of the thermal structure and spatio-temporal characteristics of the southern polar atmosphere. Tropospheric data sets will be analyzed by multivariate statistical methods and will allow the identification of dominant atmospheric circulation patterns as well as their temporal variability. An overview of the data sets and first results will be presented.
Polarization measurement through combination polarizers
NASA Astrophysics Data System (ADS)
Bai, Yunfeng; Li, Linjun; He, Zhelong; Liu, Yanwei; Ma, Cheng; Shi, Guang; Liu, Lu
2014-02-01
Polarization measurement approaches only using polarizer and grating is present. The combination polarizers consists of two polarizers: one is γ degree with the X axis; the other is along the Y axis. Binary grating is covered by the combination polarizers, and based on Fraunhofer diffraction, the diffraction intensity formula is deduced. The polarization state of incident light can be gotten by fitting the diffraction pattern with the deduced formula. Compared with the traditional polarization measurement method, this measurement only uses polarizer and grating, therefore, it can be applied to measure a wide wavelength range without replacing device in theory.
NASA Astrophysics Data System (ADS)
Di, Huige; Hua, Hangbo; Cui, Yan; Hua, Dengxin; He, Tingyao; Wang, Yufeng; Yan, Qing
2017-02-01
In this study, a multi-wavelength polarization lidar was developed at the Lidar Center for Atmosphere Remote Sensing, in Xi'an, China to study the vertical distribution of the optical and microphysical properties of smog aerosols. To better understand smog, two events with different haze conditions observed in January 2015 were analyzed in detail. Using these data, we performed a vertical characterization of smog evolution using the lidar range-squared-corrected signal and the aerosol depolarization ratio. Using inversion with regularization, we retrieved the vertical distribution of aerosol microphysical properties, including volume size distribution, volume concentration, number concentration and effective radius. We also used the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model to analyze aerosol sources during the two episodes. Our results show that the most polluted area in the lower troposphere during smog episodes is located below a height of 1 km above the ground level; under more severe smog conditions, it can be below 0.5 km. In the case of severe smog, we found a large number of spherical and fine particles concentrated in the very low troposphere, even below 0.5 km. Surprisingly, a dust layer with a slight depolarization ratio was observed above the smog layer.
Yang, Jun; Smith, Humphrey G; Sherratt, Thomas N; Wilkinson, David M
2010-05-01
A long-standing debate in microbial ecology is the extent to which free-living microorganisms exhibit cosmopolitan distributions. We use a comparison of testate amoebae communities in cold "polar" locations (Arctic, Antarctic, and Tibet) to investigate how a microorganism's size affects its probability of having a cosmopolitan distribution. We show that the probability a given taxa being reported in all three locations increases as testate size decreases. Likewise, excluding those testates found only in Tibet, very small testates (<20 microm) are more likely to occur in both the Arctic and Antarctic than in either of these poles alone. Attempting to correct for phylogeny reduces the number of statistically significant relationships--both because of decreased sample size and potentially real phylogenetic patterns, although some size-dependent effects were still apparent. In particular, taxa found in both the Arctic and Antarctic poles were significantly smaller than congeneric taxa found only in Tibet. This pattern may in part be due to habitat effects, with the Tibetan samples being more likely to have come from aquatic sites which may be more suitable for larger taxa. Overall, our analysis suggests that, at least within testate amoebae, a cosmopolitan distribution becomes increasingly common as median taxon size decreases.
Yuan, Kai-Jun Chelkowski, Szczepan; Bandrauk, André D.
2015-04-14
We study effects of pulse durations on molecular photoelectron angular distributions (MPADs) in ultrafast circular polarization ultraviolet resonant ionization processes. Simulations performed on aligned H{sub 2}{sup +} by numerically solving time dependent Schrödinger equations show rotations of MPADs with respect to the molecular symmetry axes. It is found that in multi-photon resonant ionization processes, rotation angles are sensitive to pulse durations, which we attribute to the coherent resonant excitation between the ground state and the intermediate excited electronic state induced by Rabi oscillations. Multi-photon nonresonant and single photon ionization processes are simulated and compared which exhibit a constant rotation angle. An asymmetry parameter is introduced to describe the pulse duration sensitivity by perturbation theory models. Influence of pulse frequency detunings on MPADs is also investigated where oscillations of rotations are absent at long pulse durations due to nonresonance excitation.
QCD-aware partonic jet clustering for truth-jet flavour labelling
NASA Astrophysics Data System (ADS)
Buckley, Andy; Pollard, Chris
2016-02-01
We present an algorithm for deriving partonic flavour labels to be applied to truth particle jets in Monte Carlo event simulations. The inputs to this approach are final pre-hadronisation partons, to remove dependence on unphysical details such as the order of matrix element calculation and shower generator frame recoil treatment. These are clustered using standard jet algorithms, modified to restrict the allowed pseudojet combinations to those in which tracked flavour labels are consistent with QCD and QED Feynman rules. The resulting algorithm is shown to be portable between the major families of shower generators, and largely insensitive to many possible systematic variations: it hence offers significant advantages over existing ad hoc labelling schemes. However, it is shown that contamination from multi-parton scattering simulations can disrupt the labelling results. Suggestions are made for further extension to incorporate more detailed QCD splitting function kinematics, robustness improvements, and potential uses for truth-level physics object definitions and tagging.
Revealing Partons in Hadrons: From the ISR to the SPS Collider
NASA Astrophysics Data System (ADS)
Darriulat, Pierre; di Lella, Luigi
2015-07-01
Our understanding of the structure of hadrons has developed during the seventies and early eighties from a few vague ideas to a precise theory, Quantum Chromodynamics, that describes hadrons as made of elementary partons (quarks and gluons). Deep inelastic scattering of electrons and neutrinos on nucleons and electron-positron collisions have played a major role in this development. Less well known is the role played by hadron collisions in revealing the parton structure, studying the dynamic of interactions between partons and offering an exclusive laboratory for the direct study of gluon interactions. The present article recalls the decisive contributions made by the CERN Intersecting Storage Rings and, later, the proton-antiproton SPS Collider to this chapter of physics.
Two jet energy and rapidity distributions
Blazey, G.C.; For the D {O} Collaboration
1992-11-01
The D0 detector has been recording data at the Tevatron {bar p}p Collider since May 1992. Because the D0 calorimeter is hermetic and has large acceptance it is well suited for semi-exclusive final state jet studies. We present a primary measurement of the distribution d{sup 3}N/dE{sub t1}/d{eta}{sub 1}/d{eta}{sub 2} at {radical}s TeV over a large range of {eta}. The sensitivity of this cross-section to parton momentum distributions and the ability of D0 to discriminate between possible parton distributions is discussed.
Medium-induced gluon radiation in hard forward parton scattering in the saturation formalism
NASA Astrophysics Data System (ADS)
Munier, Stéphane; Peigné, Stéphane; Petreska, Elena
2017-01-01
We derive the medium-induced, fully coherent soft gluon radiation spectrum associated with the hard forward scattering of an energetic parton off a nucleus, in the saturation formalism within the Gaussian approximation for the relevant correlators of Wilson lines and for finite number of colors. The validity range of the result is rigorously specified by keeping track of the order of magnitude of subleading contributions to the spectrum. The connection between the saturation formalism and the opacity expansion used in previous studies of the same observable is made apparent. Our calculation sets the basis for further studies of the interplay between saturation and fully coherent energy loss in hard forward parton scattering.
Studies of Parton Propagation and Hadron Formation in the Space-Time Domain
Brooks, Will; Hakobyan, Hayk
2008-10-13
Over the past decade, new data from HERMES, Jefferson Lab, Fermilab, and RHIC that connect to parton propagation and hadron formation have become available. Semi-inclusive DIS on nuclei, the Drell-Yan reaction, and heavy-ion collisions all bring different kinds of information on parton propagation within a medium, while the most direct information on hadron formation comes from the DIS data. Over the next decade one can hope to begin to understand these data within a unified picture. We briefly survey the most relevant data and the common elements of the physics picture, then highlight the new Jefferson Lab data, and close with a prospective for the future.
Examining the Crossover from the Hadronic to Partonic Phase in QCD
Xu Mingmei; Yu Meiling; Liu Lianshou
2008-03-07
A mechanism, consistent with color confinement, for the transition between perturbative and physical vacua during the gradual crossover from the hadronic to partonic phase is proposed. The essence of this mechanism is the appearance and growing up of a kind of grape-shape perturbative vacuum inside the physical one. A percolation model based on simple dynamics for parton delocalization is constructed to exhibit this mechanism. The crossover from hadronic matter to sQGP (strongly coupled quark-gluon plasma) as well as the transition from sQGP to weakly coupled quark-gluon plasma with increasing temperature is successfully described by using this model.
Polar cap potential distributions during periods of positive IMF B(sub y) and B(sub z)
NASA Technical Reports Server (NTRS)
Burke, William J.; Basinska, Ewa M.; Maynard, Nelson C.; Hanson, William B.; Slavin, James A.; Winningham, J. David
1994-01-01
We compare the DE-2 electric field measurements used by HEPPNER and MAYNARD (1987) to illustrate strongly distorted, BC convection patterns for interplanetary magnetic field (IMF) B(sub z) greater than 0 and large absolute value of B(sub y), with simultaneous detections of particle spectra, plasma drifts and magnetic perturbations. Measured potentials greater than 50 keV, driven by the solar wind speeds exceeding 500 km/s, are greater than published correlation analysis predictions by up to 27%. The potential distributions show only two extrema and thus support the basic conclusion that under these conditions the solar wind/IMF drives two-rather than four-cell convection patterns. However, several aspects of the distorted two-cell convection pattern must be revised. In addition to the strong east-west convection in the vicinity of the cusp, indicated by Heppner and Maynard, we also detect comparable components of sunward (equatorward) plasma flow. Combined equipotential and particle precipitation distributions indicate the presence of a lobe cell embedded within the larger, afternoon reconnection cell. Both types rotate in the same sense, with the lobe cell carrying 20-40% of the total afternoon cell potential. We detected no lobe cell within morning convection cell.
Feng, Hong-xia; Sam, Rokayya; Jiang, Lian-zhou; Li, Yang; Cao, Wen-ming
2016-01-01
Camellia seed oil (CSO) is rich in oleic acid and has a high number of active components, which give the oil high nutritional value and a variety of biological activity. The aim of the present study was to determine the changes in the content and distribution of total polar compounds (TPC) in CSO during heating. TPC were isolated by means of preparative flash chromatography and further analyzed by high-performance size-exclusion chromatography (HPSEC). The TPC content of CSO increased from 4.74% to 25.29%, showing a significantly lower formation rate as compared to that of extra virgin olive oil (EVOO) and soybean oil (SBO) during heating. Furthermore, heating also resulted in significant differences (P<0.05) in the distribution of TPC among these oils. Though the content of oxidized triacylglycerol dimers, oxidized triacylglycerol oligomers, and oxidized triacylglycerol monomers significantly increased in all these oils, their increased percentages were much less in CSO than those in EVOO, indicating that CSO has a greater ability to resist oxidation. This work may be useful for the food oil industry and consumers in helping to choose the correct oil and to decide on the useful lifetime of the oil. PMID:27819135
Liu, Eric Yi; Morgan, Andrew P.; Chesler, Elissa J.; Wang, Wei; Churchill, Gary A.; Pardo-Manuel de Villena, Fernando
2014-01-01
Since the publication of the first comprehensive linkage map for the laboratory mouse, the architecture of recombination as a basic biological process has become amenable to investigation in mammalian model organisms. Here we take advantage of high-density genotyping and the unique pedigree structure of the incipient Collaborative Cross to investigate the roles of sex and genetic background in mammalian recombination. Our results confirm the observation that map length is longer when measured through female meiosis than through male meiosis, but we find that this difference is modified by genotype at loci on both the X chromosome and the autosomes. In addition, we report a striking concentration of crossovers in the distal ends of autosomes in male meiosis that is absent in female meiosis. The presence of this pattern in both single- and double-recombinant chromosomes, combined with the absence of a corresponding asymmetry in the distribution of double-strand breaks, indicates a regulated sequence of events specific to male meiosis that is anchored by chromosome ends. This pattern is consistent with the timing of chromosome pairing and evolutionary constraints on male recombination. Finally, we identify large regions of reduced crossover frequency that together encompass 5% of the genome. Many of these “cold regions” are enriched for segmental duplications, suggesting an inverse local correlation between recombination rate and mutation rate for large copy number variants. PMID:24578350
Liu, Eric Yi; Morgan, Andrew P; Chesler, Elissa J; Wang, Wei; Churchill, Gary A; Pardo-Manuel de Villena, Fernando
2014-05-01
Since the publication of the first comprehensive linkage map for the laboratory mouse, the architecture of recombination as a basic biological process has become amenable to investigation in mammalian model organisms. Here we take advantage of high-density genotyping and the unique pedigree structure of the incipient Collaborative Cross to investigate the roles of sex and genetic background in mammalian recombination. Our results confirm the observation that map length is longer when measured through female meiosis than through male meiosis, but we find that this difference is modified by genotype at loci on both the X chromosome and the autosomes. In addition, we report a striking concentration of crossovers in the distal ends of autosomes in male meiosis that is absent in female meiosis. The presence of this pattern in both single- and double-recombinant chromosomes, combined with the absence of a corresponding asymmetry in the distribution of double-strand breaks, indicates a regulated sequence of events specific to male meiosis that is anchored by chromosome ends. This pattern is consistent with the timing of chromosome pairing and evolutionary constraints on male recombination. Finally, we identify large regions of reduced crossover frequency that together encompass 5% of the genome. Many of these "cold regions" are enriched for segmental duplications, suggesting an inverse local correlation between recombination rate and mutation rate for large copy number variants.
Drell-Yan production at NNLL'+NNLO matched to parton showers
NASA Astrophysics Data System (ADS)
Alioli, Simone; Bauer, Christian W.; Berggren, Calvin; Tackmann, Frank J.; Walsh, Jonathan R.
2015-11-01
We present results for Drell-Yan production from the geneva Monte-Carlo framework. We combine the fully differential next-to-next-to leading order (NNLO) calculation with higher-order resummation in the 0-jettiness resolution variable. The resulting parton-level events are further combined with parton showering and hadronization provided by pythia8. The 0-jettiness resummation is carried out to NNLL' , which consistently incorporates all singular virtual and real NNLO corrections. It thus provides a natural perturbative connection between the NNLO calculation and the parton shower regime, including a systematic assessment of perturbative uncertainties. In this way, inclusive observables are correct to NNLO, up to small power corrections in the resolution cutoff. Furthermore, the perturbative accuracy of zero-jet-like resummation variables is significantly improved beyond the parton shower approximation. We provide comparisons with LHC measurements of Drell-Yan production at 7 TeV from ATLAS, CMS, and LHCb. As already observed in e+e- collisions, for resummation-sensitive observables, the agreement with data is noticeably improved by using a lower value of αs(MZ)=0.1135 .
Global extraction of the parton-to-pion fragmentation functions at NLO accuracy in QCD
NASA Astrophysics Data System (ADS)
Hernández-Pinto, R. J.; Epele, M.; de Florian, D.; Sassot, R.; Stratmann, M.
2016-10-01
In this review, we discuss the results on the parton-to-pion fragmentation functions obtained in a combined NLO fit to data of single-inclusive hadron production in electron-positron annihilation, proton-proton collisions, and lepton-nucleon deep-inelastic scattering. A more complete discussion can be found in Ref. [1].
Drell-Yan Lepton pair production at NNLO QCD with parton showers
Hoeche, Stefan; Li, Ye; Prestel, Stefan
2015-04-13
We present a simple approach to combine NNLO QCD calculations and parton showers, based on the UNLOPS technique. We apply the method to the computation of Drell-Yan lepton-pair production at the Large Hadron Collider. We comment on possible improvements and intrinsic uncertainties.
Making Sense in the City: Dolly Parton, Early Reading and Educational Policy-Making
ERIC Educational Resources Information Center
Hall, Christine; Jones, Susan
2016-01-01
In this paper, we present a case study of a philanthropic literacy initiative, Dolly Parton's Imagination Library, a book-gifting scheme for under 5s, and consider the impact of the scheme on literacy policy in the English city where it was introduced. We bring four lenses to bear on the case study. First, we analyse the operation of the scheme in…
Neutron spin structure with polarized deuterons and spectator proton tagging at EIC
Cosyn, W.; Guzey, V.; Higinbotham, D. W.; Hyde, C.; Kuhn, S.; Nadel-Turonski, P.; Park, K.; Sargsian, M.; Strikman, M.; Weiss, C.
2014-10-27
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.
Neutron spin structure with polarized deuterons and spectator proton tagging at EIC
Cosyn, W.; Guzey, V.; Higinbotham, D. W.; ...
2014-10-27
The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleusmore » rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.« less
QCD Corrections in Transversely Polarized Scattering
Vogelsang,W.
2008-10-06
We discuss two recent calculations of higher-order QeD corrections to scattering of transversely polarized hadrons. A basic concept underlying much of the theoretical description of high-energy hadronic scattering is the factorization theorem, which states that large momentum-transfer reactions may be factorized into long-distance pieces that contain information on the structure of the nucleon in terms of its parton densities, and parts that are short-distance and describe the hard interactions of the partons. Two crucial points are that on the one hand the long-distance contributions are universal, i.e., they are the same in any inelastic reaction under consideration, and that on the other hand the short-distance pieces depend only on the large scales related to the large momentum transfer in the overall reaction and, therefore, may be evaluated using QCD perturbation theory. The lowest order for the latter can generally only serve to give a rough description of the reaction under study. It merely captures the main features, but does not usually provide a quantitative understanding. The first-order ('next-to-leading order' (NLO)) corrections are generally indispensable in order to arrive at a firmer theoretical prediction for hadronic cross sections, and in some cases even an all-order resummation of large perturbative corrections is needed. In the present paper we win discuss two calculations [1, 2] of higher-order QeD corrections to transversely polarized scattering.
PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0
NASA Astrophysics Data System (ADS)
Sa, Ben-Hao; Zhou, Dai-Mei; Yan, Yu-Liang; Dong, Bao-Guo; Cai, Xu
2013-05-01
a given impact parameter possesses an almond-like spatial asymmetry. Because of the strong parton rescattering, the local thermal equilibrium and asymmetric pressure gradient may build up in this initial fireball. The asymmetric pressure gradient then drives a collective anisotropic expansion. The expansion along the almond minor axis (along the large pressure gradient) is faster than the one along the major axis. This results in a strong asymmetric transverse momentum azimuthal distribution and hence a large elliptic flow coefficient v2 of the final hadronic state. As mentioned in [6], PACIAE is a parton and hadron cascade model for the ultra-relativistic nuclear collisions and is based on PYTHIA [7]. In the PACIAE model, a nucleus-nucleus collision is decomposed into a sequence of nucleon-nucleon (NN) collisions according to the collision geometry and the NN total cross section. Each NN collision is performed, in turn, by the PYTHIA model with the string fragmentation switched-off temporarily and the diquark (anti-diquark) broken into quark pairs (anti-quark pairs) randomly. The parton rescattering then proceeds. This parton evolution stage is followed by the hadronization at the moment of partonic freeze-out (exhausting the partonic collisions). The Lund string fragmentation regime and/or phenomenological coalescence model is provided for the hadronization. Then the rescattering among produced hadrons is dealt with by the usual two body collision model [6]. In the PYTHIA model [7] once the transverse momentum pT of a final state hadron generated from the string fragmentation and/or the unstable particle decay is randomly sampled, the px and py components are randomly placed on the circle with radius of pT. This px and py determination may strongly cancel the final state transverse momentum anisotropy developed dynamically. The charged particle transverse sphericity [8-10] may reach to unity (isotropic). This is inconsistent with the experimental observation that
1989-09-30
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Carrizo, Daniel; Gustafsson, Örjan
2011-02-15
Assessment of the Arctic as a global repository of polychlorinated biphenyls (PCBs) and of uptake processes in the base of its marine food chain hinges on reliable information of PCB distribution in surface seawater, yet there is a scarcity of quality-assured PCB measurements in this key compartment. Here, surface seawater PCB concentrations and congener fingerprints are evaluated for all seven pan-Arctic shelf seas and for the interior basins. Particulate and dissolved PCBs were collected via trace-clean protocols on three basin-wide expeditions (AO-01, Beringia-2005, and ISSS-08). Concentrations of the sum of 13 abundant congeners (∑13PCB) were 0.13-21 pg/L, with higher concentrations in the shelf seas and lower concentrations in the Central Arctic Basin. Trichlorinated PCBs constituted about half of the total loadings in the Eastern Arctic (Beaufort, Chukchi, East Siberian, and Laptev Seas) and in the Central Basin, indicating an atmospheric source. In contrast, hexachlorinated PCBs were more abundant than tri-PCBs in the western sector, suggesting a role also for waterborne transport from regions of heavy PCB consumption in North America and Europe. Finally, the inventory of ∑13PCB in the polar mixed layer of the entire Arctic Ocean was 0.39 ton, which implies that only 0.0008% of historical PCB emissions are now residing in Arctic surface waters.
Si, Weijian; Zhao, Pinjiao; Qu, Zhiyu
2016-01-01
This paper presents an L-shaped sparsely-distributed vector sensor (SD-VS) array with four different antenna compositions. With the proposed SD-VS array, a novel two-dimensional (2-D) direction of arrival (DOA) and polarization estimation method is proposed to handle the scenario where uncorrelated and coherent sources coexist. The uncorrelated and coherent sources are separated based on the moduli of the eigenvalues. For the uncorrelated sources, coarse estimates are acquired by extracting the DOA information embedded in the steering vectors from estimated array response matrix of the uncorrelated sources, and they serve as coarse references to disambiguate fine estimates with cyclical ambiguity obtained from the spatial phase factors. For the coherent sources, four Hankel matrices are constructed, with which the coherent sources are resolved in a similar way as for the uncorrelated sources. The proposed SD-VS array requires only two collocated antennas for each vector sensor, thus the mutual coupling effects across the collocated antennas are reduced greatly. Moreover, the inter-sensor spacings are allowed beyond a half-wavelength, which results in an extended array aperture. Simulation results demonstrate the effectiveness and favorable performance of the proposed method. PMID:27258271
Höche, Stefan; Schönherr, Marek
2012-11-01
We quantify uncertainties in the Monte Carlo simulation of inclusive and dijet final states, which arise from using the MC@NLO technique for matching next-to-leading order parton-level calculations and parton showers. We analyse a large variety of data from early measurements at the LHC. In regions of phase space where Sudakov logarithms dominate over high-energy effects, we observe that the main uncertainty can be ascribed to the free parameters of the parton shower. In complementary regions, the main uncertainty stems from the considerable freedom in the simulation of underlying events.
Non-perturbative inputs for gluon distributions in the hadrons
NASA Astrophysics Data System (ADS)
Ermolaev, B. I.; Troyan, S. I.
2017-03-01
Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K_T-and collinear factorizations.
NASA Astrophysics Data System (ADS)
Danilyan, G. V.; Klenke, J.; Kopach, Yu. N.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.
2014-06-01
The results of an experiment devoted to searches for effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U nuclei are presented. The effects discovered in these angular distributions are opposite in sign to their counterparts in the polarized-neutron-induced fission of 235U nuclei. This is at odds with data on the relative signs of respective effects in the angular distribution of alpha particles from the ternary fission of the same nuclei and may be indicative of problems in the model currently used to describe the effect in question. The report on which this article is based was presented at the seminar held at the Institute of Theoretical and Experimental Physics and dedicated to the 90th anniversary of the birth of Yu.G. Abov, corresponding member of Russian Academy of Sciences, Editor in Chief of the journal Physics of Atomic Nuclei.
NASA Technical Reports Server (NTRS)
Mcguire, James P., Jr.; Chipman, Russell A.
1990-01-01
The analysis of the polarization characteristics displayed by optical systems can be divided into two categories: geometrical and physical. Geometrical analysis calculates the change in polarization of a wavefront between pupils in an optical instrument. Physical analysis propagates the polarized fields wherever the geometrical analysis is not valid, i.e., near the edges of stops, near images, in anisotropic media, etc. Polarization aberration theory provides a starting point for geometrical design and facilitates subsequent optimization. The polarization aberrations described arise from differences in the transmitted (or reflected) amplitudes and phases at interfaces. The polarization aberration matrix (PAM) is calculated for isotropic rotationally symmetric systems through fourth order and includes the interface phase, amplitude, linear diattenuation, and linear retardance aberrations. The exponential form of Jones matrices used are discussed. The PAM in Jones matrix is introduced. The exact calculation of polarization aberrations through polarization ray tracing is described. The report is divided into three sections: I. Rotationally Symmetric Optical Systems; II. Tilted and Decentered Optical Systems; and Polarization Analysis of LIDARs.
Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs)
NASA Astrophysics Data System (ADS)
Engelhardt, M.; Musch, B.; Bhattacharya, T.; Green, J. R.; Gupta, R.; Hägler, P.; Krieg, S.; Negele, J.; Pochinsky, A.; Schäfer, A.; Syritsyn, S.; Yoon, B.
2016-03-01
An ongoing program of evaluating TMD observables within Lattice QCD is reviewed, summarizing recent progress with respect to several challenges faced by such calculations. These lattice calculations are based on a definition of TMDs through hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for a lattice calculation. Data on the naively T-odd Sivers and Boer-Mulders effects as well as the transversity TMD are presented.
Bedlinskiy, Ivan; Niccolai, Silvia; Stoler, Paul; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anghinolfi, Marco; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bennett, Robert; Biselli, Angela; Bookwalter, Craig; Boyarinov, Sergey; Briscoe, William; Brooks, Williams; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Contalbrigo, Marco; Crede, Volker; D'Angelo, Annalisa; Daniel, Aji; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francoi-Xavier; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Heddle, David; Hicks, Kenneth; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khanddaker, Mahbubul; Khertarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Franz; Koirala, Suman; Kubarovsky, A; Kuhn, Sebastian; Kuleshov, Sergey; Kvaltine, Nicholas; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Mao, Yuqing; Markov, Nikolai; Martinez, D; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Moutarde, Herve; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Permuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pereira, Sergio; Phelps, Evan; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Ricco, Giovanni; Rimal, Dipak; Ripani, Marco; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Saylor, Nicholas; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Samuel; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Tian, Ye; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Weygan, Dennis; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen; Zonta, Irene
2012-09-01
Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $\\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.
NASA Astrophysics Data System (ADS)
McDunn, T. L.; Bougher, S. W.; Mischna, M. A.; Murphy, J. R.
2012-12-01
Polar warming is a dynamically induced temperature enhancement over mid-to-high latitudes that results in a reversed (poleward) meridional temperature gradient. This phenomenon was recently characterized over the 40-90 km altitude region [1] based on nearly three martian years of Mars Climate Sounder observations [2, 3]. Here we investigate which forcing mechanisms affect the magnitude and distribution of the observed polar warming by conducting simulations with the Mars Weather Research and Forecasting General Circulation Model [4, 5]. We present simulations confirming the influence topography [6] and dust loading [e.g., 7] have upon polar warming. We then present simulations illustrating the modulating influence gravity wave momentum deposition exerts upon polar warming, consistent with previous modeling studies [e.g., 8]. The results of this investigation suggest the magnitude and distribution of polar warming in the martian middle atmosphere is modified by gravity wave activity and that the characteristics of the gravity waves that most significantly affect polar warming vary with season. References: [1] McDunn, et al., 2012 (JGR), [2]Kleinböhl, et al., 2009 (JGR), [3] Kleinböhl, et al., 2011 (JQSRT), [4] Richardson, et al., 2007 (JGR), [5] Mischna, et al., 2011 (Planet. Space Sci.), [6] Richardson and Wilson, 2002 (Nature), [7] Haberle, et al., 1982 (Icarus), [8] Barnes, 1990 (JGR).
Off-shell single-top production at NLO matched to parton showers
Frederix, R.; Frixione, S.; Papanastasiou, A. S.; Prestel, S.; Torrielli, P.
2016-06-06
We study the hadroproduction of a Wb pair in association with a light jet, focusing on the dominant t-channel contribution and including exactly at the matrix-element level all non-resonant and off-shell effects induced by the finite top-quark width. Our simulations are accurate to the next-to-leading order in QCD, and are matched to the Herwig6 and Pythia8 parton showers through the MC@NLO method. We present phenomenological results relevant to the 8 TeV LHC, and carry out a thorough comparison to the case of on-shell t-channel single-top production. Furthermore, we formulate our approach so that it can be applied to the general case of matrix elements that feature coloured intermediate resonances and are matched to parton showers.
Off-shell single-top production at NLO matched to parton showers
Frederix, R.; Frixione, S.; Papanastasiou, A. S.; ...
2016-06-06
We study the hadroproduction of a Wb pair in association with a light jet, focusing on the dominant t-channel contribution and including exactly at the matrix-element level all non-resonant and off-shell effects induced by the finite top-quark width. Our simulations are accurate to the next-to-leading order in QCD, and are matched to the Herwig6 and Pythia8 parton showers through the MC@NLO method. We present phenomenological results relevant to the 8 TeV LHC, and carry out a thorough comparison to the case of on-shell t-channel single-top production. Furthermore, we formulate our approach so that it can be applied to the generalmore » case of matrix elements that feature coloured intermediate resonances and are matched to parton showers.« less
COLLINEAR SPLITTING, PARTON EVOLUTION AND THE STRANGE-QUARK ASYMMETRY OF THE NUCLEON IN NNLO QCD.
RODRIGO,G.CATANI,S.DE FLORIAN, D.VOGELSANG,W.
2004-04-25
We consider the collinear limit of QCD amplitudes at one-loop order, and their factorization properties directly in color space. These results apply to the multiple collinear limit of an arbitrary number of QCD partons, and are a basic ingredient in many higher-order computations. In particular, we discuss the triple collinear limit and its relation to flavor asymmetries in the QCD evolution of parton densities at three loops. As a phenomenological consequence of this new effect, and of the fact that the nucleon has non-vanishing quark valence densities, we study the perturbative generation of a strange-antistrange asymmetry s(x)-{bar s}(x) in the nucleon's sea.
Diphoton production in the ADD model to NLO + parton shower accuracy at the LHC
NASA Astrophysics Data System (ADS)
Frederix, R.; Mandal, Manoj K.; Mathews, Prakash; Ravindran, V.; Seth, Satyajit; Torrielli, P.; Zaro, M.
2012-12-01
In this paper, we present the next-to-leading order predictions for diphoton production in the ADD model, matched to the HERWIG parton shower using the MC@NLO formalism. A selection of the results is presented for d = 2-6 extra dimensions, using generic cuts as well as analysis cuts mimicking the search strategies as pursued by the ATLAS and CMS experiments.
One-Loop Multi-Parton Amplitudes with a Vector Boson for the LHC
Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Ita, H.; Kosower, D.A.; Maitre, D.; /SLAC
2008-08-11
In this talk, we present the first, numerically stable, results for the one-loop amplitudes needed for computing W; Z + 3 jet cross sections at the LHC to next-to-leading order in the QCD coupling. We implemented these processes in BlackHat, an automated program based on on-shell methods. These methods scale very well with increasing numbers of external partons, and are applicable to a wide variety of problems of phenomenological interest at the LHC.
Ma, Guo -Liang; Bzdak, Adam
2014-11-04
In this study, we show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton–parton cross-section of σ = 1.5 – 3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton–proton and proton–nucleus collisions at the Large Hadron Collider.
Alwall, J.; Hoche, S.; Krauss, F.; Lavesson, N.; Lonnblad, L.; Maltoni, F.; Mangano, M.L.; Moretti, M.; Papadopoulos, C.G.; Piccinini, F.; Schumann, S.; Treccani, M.; Winter, J.; Worek, M.; /SLAC /Durham U., IPPP /Lund U. /Louvain U. /CERN /Ferrara U. /INFN, Ferrara /Athens U. /INFN, Pavia /Dresden, Tech. U. /Karlsruhe U., TP /Silesia U.
2007-06-27
We compare different procedures for combining fixed-order tree-level matrix-element generators with parton showers. We use the case of W-production at the Tevatron and the LHC to compare different implementations of the so-called CKKW and MLM schemes using different matrix-element generators and different parton cascades. We find that although similar results are obtained in all cases, there are important differences.
NASA Astrophysics Data System (ADS)
Berrington, Robert C.; Brotherton, Michael S.; Gallagher, Sarah C.; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D.; Hall, Patrick B.; Laurent-Muehleisen, S. A.
2013-12-01
We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e. an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Γ = 1.7 or flatter at a >99 per cent confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 1023 cm-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet and an X-ray absorber not dissimilar from that of other broad absorption line quasars.
Clustering of polarization-encoded images.
Zallat, Jihad; Collet, Christophe; Takakura, Yoshitate
2004-01-10
Polarization-encoded imaging consists of the distributed measurements of polarization parameters for each pixel of an image. We address clustering of multidimensional polarization-encoded images. The spatial coherence of polarization information is considered. Two methods of analysis are proposed: polarization contrast enhancement and a more-sophisticated image-processing algorithm based on a Markovian model. The proposed algorithms are applied and validated with two different Mueller images acquired by a fully polarimetric imaging system.
Amstrup, S.D.; ,; Lentfer, J.W.
1988-01-01
Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.
Manzhos, Sergei; Romanescu, Constantin; Loock, Hans-Peter; Underwood, Jonathan G.
2004-12-15
A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.
Manzhos, Sergei; Romanescu, Constantin; Loock, Hans-Peter; Underwood, Jonathan G
2004-12-15
A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.
Murray, Peter J
2017-02-10
Macrophage polarization refers to how macrophages have been activated at a given point in space and time. Polarization is not fixed, as macrophages are sufficiently plastic to integrate multiple signals, such as those from microbes, damaged tissues, and the normal tissue environment. Three broad pathways control polarization: epigenetic and cell survival pathways that prolong or shorten macrophage development and viability, the tissue microenvironment, and extrinsic factors, such as microbial products and cytokines released in inflammation. A plethora of advances have provided a framework for rationally purifying, describing, and manipulating macrophage polarization. Here, I assess the current state of knowledge about macrophage polarization and enumerate the major questions about how activated macrophages regulate the physiology of normal and damaged tissues.
ERIC Educational Resources Information Center
Bowers, Wayne A.
This monograph was written for the Conference of the New Instructional Materials in Physics, held at the University of Washington in summer, 1965. It is intended for students who have had an introductory college physics course. It seeks to provide an introduction to the idea of distributions in general, and to some aspects of the subject in…
Krylov, Alexander A; Chernykh, Dmitriy S; Arutyunyan, Natalia R; Grebenyukov, Vyacheslav V; Pozharov, Anatoly S; Obraztsova, Elena D
2016-05-20
We report on the stable picosecond and femtosecond pulse generation from the bidirectional erbium-doped all-fiber ring laser hybridly mode-locked with a coaction of a single-walled carbon nanotube-based saturable absorber and nonlinear polarization evolution that was introduced through the insertion of the short-segment polarizing fiber. Depending on the total intracavity dispersion value, the laser emits conservative solitons, transform-limited Gaussian pulses, or highly chirped stretched pulses with almost 20 nm wide parabolic spectrum in both clockwise (CW) and counterclockwise (CCW) directions of the ring. Owing to the polarizing action in the cavity, we have demonstrated for the first time, to the best of our knowledge, an efficient tuning of soliton pulse characteristics for both CW and CCW channels via an appropriate polarization control. We believe that the bidirectional laser presented may be highly promising for gyroscopic and other dual-channel applications.
An analysis of the impact of LHC Run I proton-lead data on nuclear parton densities.
Armesto, Néstor; Paukkunen, Hannu; Penín, José Manuel; Salgado, Carlos A; Zurita, Pía
2016-01-01
We report on an analysis of the impact of available experimental data on hard processes in proton-lead collisions during Run I at the large hadron collider on nuclear modifications of parton distribution functions. Our analysis is restricted to the EPS09 and DSSZ global fits. The measurements that we consider comprise production of massive gauge bosons, jets, charged hadrons and pions. This is the first time a study of nuclear PDFs includes this number of different observables. The goal of the paper is twofold: (i) checking the description of the data by nPDFs, as well as the relevance of these nuclear effects, in a quantitative manner; (ii) testing the constraining power of these data in eventual global fits, for which we use the Bayesian reweighting technique. We find an overall good, even too good, description of the data, indicating that more constraining power would require a better control over the systematic uncertainties and/or the proper proton-proton reference from LHC Run II. Some of the observables, however, show sizeable tension with specific choices of proton and nuclear PDFs. We also comment on the corresponding improvements as regards the theoretical treatment.
An analysis of the impact of LHC Run I proton-lead data on nuclear parton densities
NASA Astrophysics Data System (ADS)
Armesto, Néstor; Paukkunen, Hannu; Penín, José Manuel; Salgado, Carlos A.; Zurita, Pía
2016-04-01
We report on an analysis of the impact of available experimental data on hard processes in proton-lead collisions during Run I at the large hadron collider on nuclear modifications of parton distribution functions. Our analysis is restricted to the EPS09 and DSSZ global fits. The measurements that we consider comprise production of massive gauge bosons, jets, charged hadrons and pions. This is the first time a study of nuclear PDFs includes this number of different observables. The goal of the paper is twofold: (i) checking the description of the data by nPDFs, as well as the relevance of these nuclear effects, in a quantitative manner; (ii) testing the constraining power of these data in eventual global fits, for which we use the Bayesian reweighting technique. We find an overall good, even too good, description of the data, indicating that more constraining power would require a better control over the systematic uncertainties and/or the proper proton-proton reference from LHC Run II. Some of the observables, however, show sizeable tension with specific choices of proton and nuclear PDFs. We also comment on the corresponding improvements as regards the theoretical treatment.
NASA Technical Reports Server (NTRS)
Robin, G. D.
1984-01-01
Two fields of research on polar ice sheets are likely to be of dominant interest during the 1990s. These are: the role of polar ice sheets in the hydrological cycle ocean-atmosphere-ice sheets-oceans, especially in relation to climate change; and the study and interpretation of material in deep ice cores to provide improved knowledge of past climates and of the varying levels of atmospheric constituents such as CO2, NOx, SO2, aerosols, etc., over the past 200,000 years. Both topics require a better knowledge of ice dynamics. Many of the studies that should be undertaken in polar regions by Earth Observing System require similar instruments and techniques to those used elsewhere over oceans and inland surfaces. However to study polar regions two special requirements need to be met: Earth Observing System satellite(s) need to be in a sufficiently high inclination orbit to cover most of the polar regions. Instruments must also be adapted, often by relatively limited changes, to give satisfactory data over polar ice. The observational requirements for polar ice sheets in the 1990s are summarized.
Influences of polar auxin transport on polarity of adventitious bud formation in hybrid populas
Kim, Myung Won ); Hackett, W. )
1989-04-01
The role of auxin and cytokinin distribution of polar regeneration of adventitious bud has been investigated. Explants from leaf midvein were labelled with {sup 14}C-NAA and {sup 14}C-BA and the radioactivity in proximal, mid, and distal portions was counted after 24h and 48h. Explants showing polar regeneration of buds on the proximal end showed a clear polar distribution of {sup 14}CNAA. Auxin transport inhibitors (NPA, TIBA) eliminated polar distribution of auxin and reduced polarity of bud formation and the total number of buds formed, but did not reduce callus formation. Increased concentration of Ca(NO{sub 3}){sub 2} decreased polarity of bud formation and increased the number of buds formed but did not affect the distribution of auxin of cytokinin. Some factor in addition to polar distribution of auxin or cytokinin-auxin ratio appears to influence the polarity of adventitious bud formation.
Nicholson, Stephen P
2012-01-01
People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues.
NASA Astrophysics Data System (ADS)
Aaij, R.; Abellán Beteta, C.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Aquines Gutierrez, O.; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Bellee, V.; Belloli, N.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Bettler, M.-O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Billoir, P.; Bird, T.; Birnkraut, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borisyak, M.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Braun, S.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Buchanan, E.; Burr, C.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Campora Perez, D.; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cassina, L.; Castillo Garcia, L.; Cattaneo, M.; Cauet, Ch.; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chefdeville, M.; Chen, S.; Cheung, S.-F.; Chiapolini, N.; Chrzaszcz, M.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Dall'Occo, E.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Aguiar Francisco, O.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Simone, P.; Dean, C.-T.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Déléage, N.; Demmer, M.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Ruscio, F.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suárez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dufour, L.; Dujany, G.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Färber, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fohl, K.; Fol, P.; Fontana, M.; Fontanelli, F.; Forshaw, D. C.; Forty, R.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; García Pardiñas, J.; Garra Tico, J.; Garrido, L.; Gascon, D.; Gaspar, C.; Gauld, R.; Gavardi, L.; Gazzoni, G.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianì, S.; Gibson, V.; Girard, O. G.; Giubega, L.; Gligorov, V. V.; Göbel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gotti, C.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Grünberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadavizadeh, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; van Herwijnen, E.; Heß, M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Humair, T.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jawahery, A.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kecke, M.; Kelsey, M.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khairullin, E.; Khanji, B.; Khurewathanakul, C.; Klaver, S.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Kozeiha, M.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Krzemien, W.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kuonen, A. K.; Kurek, K.; Kvaratskheliya, T.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Lefèvre, R.; Leflat, A.; Lefrançois, J.; Lemos Cid, E.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Liles, M.; Lindner, R.; Linn, C.; Lionetto, F.; Liu, B.; Liu, X.; Loh, D.; Longstaff, I.; Lopes, J. H.; Lucchesi, D.; Lucio Martinez, M.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Lusiani, A.; Machefert, F.; Maciuc, F.; Maev, O.; Maguire, K.; Malde, S.; Malinin, A.; Manca, G.; Mancinelli, G.; Manning, P.; Mapelli, A.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Marks, J.; Martellotti, G.; Martin, M.; Martinelli, M.; Martinez Santos, D.; Martinez Vidal, F.; Martins Tostes, D.; Massafferri, A.; Matev, R.; Mathad, A.; Mathe, Z.; Matteuzzi, C.; Mauri, A.; Maurin, B.; Mazurov, A.; McCann, M.; McCarthy, J.; McNab, A.; McNulty, R.; Meadows, B.; Meier, F.; Meissner, M.; Melnychuk, D.; Merk, M.; Michielin, E.; Milanes, D. A.; Minard, M.-N.; Mitzel, D. S.; Molina Rodriguez, J.; Monroy, I. A.; Monteil, S.; Morandin, M.; Morawski, P.; Mordà, A.; Morello, M. J.; Moron, J.; Morris, A. B.; Mountain, R.; Muheim, F.; Müller, D.; Müller, J.; Müller, K.; Müller, V.; Mussini, M.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nandi, A.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Onderwater, C. J. G.; Osorio Rodrigues, B.; Otalora Goicochea, J. M.; Otto, A.; Owen, P.; Oyanguren, A.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L. L.; Pappenheimer, C.; Parker, W.; Parkes, C.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrignani, C.; Pearce, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Perret, P.; Pescatore, L.; Petridis, K.; Petrolini, A.; Petruzzo, M.; Picatoste Olloqui, E.; Pietrzyk, B.; Pilař, T.; Pinci, D.; Pistone, A.; Piucci, A.; Playfer, S.; Plo Casasus, M.; Poikela, T.; Polci, F.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Price, E.; Price, J. D.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Punzi, G.; Qian, W.; Quagliani, R.; Rachwal, B.; Rademacker, J. H.; Rama, M.; Ramos Pernas, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redi, F.; Reichert, S.; Reid, M. M.; dos Reis, A. C.; Ricciardi, S.; Richards, S.; Rihl, M.; Rinnert, K.; Rives Molina, V.; Robbe, P.; Rodrigues, A. B.; Rodrigues, E.; Rodriguez Lopez, J. A.; Rodriguez Perez, P.; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Ronayne, J. W.; Rotondo, M.; Ruf, T.; Ruiz Valls, P.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santimaria, M.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmelzer, T.; Schmidt, B.; Schneider, O.; Schopper, A.; Schubiger, M.; Schune, M.-H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Siddi, B. G.; Silva Coutinho, R.; Silva de Oliveira, L.; Simi, G.; Sirendi, M.; Skidmore, N.; Skwarnicki, T.; Smith, E.; Smith, E.; Smith, I. T.; Smith, J.; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; Souza, D.; Souza De Paula, B.; Spaan, B.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Stefkova, S.; Steinkamp, O.; Stenyakin, O.; Stevenson, S.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Sun, L.; Sutcliffe, W.; Swientek, K.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szumlak, T.; T'Jampens, S.; Tayduganov, A.; Tekampe, T.; Teklishyn, M.; Tellarini, G.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M.; Todd, J.; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Trabelsi, K.; Tran, M. T.; Tresch, M.; Trisovic, A.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagnoni, V.; Valenti, G.; Vallier, A.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vázquez Sierra, C.; Vecchi, S.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Volkov, V.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voß, C.; de Vries, J. A.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, J.; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Websdale, D.; Weiden, A.; Whitehead, M.; Wilkinson, G.; Wilkinson, M.; Williams, M.; Williams, M. P.; Williams, M.; Williams, T.; Wilson, F. F.; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.; Wyllie, K.; Xie, Y.; Xu, Z.; Yang, Z.; Yu, J.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, L.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.; Zucchelli, S.
2016-07-01
Associated production of bottomonia and open charm hadrons in pp collisions at √{s}=7 and 8 TeV is observed using data corresponding to an integrated luminosity of 3 fb-1 accumulated with the LHCb detector. The observation of five combinations, Y(1S)D0, Y(2S)D0, Y(1S)D+, Y(2S)D+ and Y(1S)D s + , is reported. Production crosssections are measured for Y(1S)D0 and Y(1S)D+ pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism. [Figure not available: see fulltext.
Treyer, Aleksandr; Müsch, Anne
2013-01-01
Hepatocytes, like other epithelia, are situated at the interface between the organism’s exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell-cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single-spanning and glycosylphosphatidylinositol-anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase-related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell-cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes. PMID:23720287
The polarization sensitivity of GRETINA
NASA Astrophysics Data System (ADS)
Wiens, Andreas; Gretina Collaboration
2014-09-01
The new tracking array GRETINA provides position information of the individual interactions of γ rays within the active Ge detector material. The position knowledge of the first two interaction points enables the calculation of the Compton scattering angle, which is sensitive to the linear polarization. Measuring the angular distribution and the linear polarization can help determine the electromagnetic character of a transition and its parity. Inelastic proton scattering on Mg (24 Mg (p , p ' γ)) provides highly polarized γ rays which we used to characterize the polarization sensitivity of GRETINA. We have studied the angular distribution and the azimuthal Compton scattering angle of the 1368 keV gamma transition after signal-decomposition and tracking, which were normalized with the unpolarized results derived from 60 Co . The a2 and a4 coefficients from the Legendre Polynomial fit of the angular distribution confirmed the high degree of polarization. We will report on the asymmetry in the azimuthal Compton scattering angle distribution which is in good agreement with a cos (2 φ) fit. We will discuss the energy dependance of the polarization sensitivity and compare the results with a GEANT4 simulation. The new tracking array GRETINA provides position information of the individual interactions of γ rays within the active Ge detector material. The position knowledge of the first two interaction points enables the calculation of the Compton scattering angle, which is sensitive to the linear polarization. Measuring the angular distribution and the linear polarization can help determine the electromagnetic character of a transition and its parity. Inelastic proton scattering on Mg (24 Mg (p , p ' γ)) provides highly polarized γ rays which we used to characterize the polarization sensitivity of GRETINA. We have studied the angular distribution and the azimuthal Compton scattering angle of the 1368 keV gamma transition after signal-decomposition and tracking
Anomalous coupling, top-mass and parton-shower effects in W + W - production
NASA Astrophysics Data System (ADS)
Bellm, J.; Gieseke, S.; Greiner, N.; Heinrich, G.; Plätzer, S.; Reuschle, C.; von Soden-Fraunhofen, J. F.
2016-05-01
We calculate the process ppto {W}+{W}-to {e}+{ν}_e{μ}-{overline{ν}}_{μ } at NLO QCD, including also effective field theory (EFT) operators mediating the ggW + W - interaction, which first occur at dimension eight. We further combine the NLO and EFT matrix elements produced by G oS am with the H erwig7/M atchbox framework, which offers the possibility to study the impact of a parton shower. We assess the effects of the anomalous couplings by comparing them to top-mass effects as well as uncertainties related to variations of the renormalisation, factorisation and hard shower scales.
Matching next-to-leading order predictions to parton showers in supersymmetric QCD
Degrande, Céline; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng
2016-02-03
We present a fully automated framework based on the FeynRules and MadGraph5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.
Double parton interactions as a background to associated HW production at the Tevatron
Bandurin, Dmitry; Golovanov, Georgy; Skachkov, Nikolai
2010-11-01
In this paper we study events with W+jets final state, produced in double parton (DP) interactions, as a background to the associated Higgs boson (H) and W production, with H {yields} b{bar b} decay, at the Tevatron. We have found that the event yield from the DP background can be quite sizable, what necessitates a choice of selection criteria to separate the HW and DP production processes. We suggest a set of variables sensitive to the kinematics of DP and HW events. We show that these variables, being used as an input to the artificial neural network, allow one to significantly improve a sensitivity to the Higgs boson production.
Lunar true polar wander inferred from polar hydrogen.
Siegler, M A; Miller, R S; Keane, J T; Laneuville, M; Paige, D A; Matsuyama, I; Lawrence, D J; Crotts, A; Poston, M J
2016-03-24
The earliest dynamic and thermal history of the Moon is not well understood. The hydrogen content of deposits near the lunar poles may yield insight into this history, because these deposits (which are probably composed of water ice) survive only if they remain in permanent shadow. If the orientation of the Moon has changed, then the locations of the shadowed regions will also have changed. The polar hydrogen deposits have been mapped by orbiting neutron spectrometers, and their observed spatial distribution does not match the expected distribution of water ice inferred from present-day lunar temperatures. This finding is in contrast to the distribution of volatiles observed in similar thermal environments at Mercury's poles. Here we show that polar hydrogen preserves evidence that the spin axis of the Moon has shifted: the hydrogen deposits are antipodal and displaced equally from each pole along opposite longitudes. From the direction and magnitude of the inferred reorientation, and from analysis of the moments of inertia of the Moon, we hypothesize that this change in the spin axis, known as true polar wander, was caused by a low-density thermal anomaly beneath the Procellarum region. Radiogenic heating within this region resulted in the bulk of lunar mare volcanism and altered the density structure of the Moon, changing its moments of inertia. This resulted in true polar wander consistent with the observed remnant polar hydrogen. This thermal anomaly still exists and, in part, controls the current orientation of the Moon. The Procellarum region was most geologically active early in lunar history, which implies that polar wander initiated billions of years ago and that a large portion of the measured polar hydrogen is ancient, recording early delivery of water to the inner Solar System. Our hypothesis provides an explanation for the antipodal distribution of lunar polar hydrogen, and connects polar volatiles to the geologic and geophysical evolution of the Moon
Angular Distributions of Drell-Yan Dimuons at Fermilab E-906/SeaQuest
NASA Astrophysics Data System (ADS)
Ramson, Bryan; Fermilab E-906/SeaQuest Collaboration
2015-10-01
Transverse momentum dependent (TMD) parton distribution functions (PDF), fragmentation functions, and their necessary theoretical framework provide a rich foundation from which to build a more descriptive, quantitative understanding of QCD and hadron structure. Fortuitously, TMD sensitive analyses of leptonic angular distributions have been a fixture in Drell-Yan experiments since the π+W CERN NA-10 of the 1980's, with particular focus on the violation of the Lam-Tung relation through a non-zero cos (2 ϕ) modulation in the angular distributions of the final-state leptons. The cos (2 ϕ) modulation is sensitive to the correlation between the motion and spin of transversely polarized (anti)quarks within their encompassing unpolarized hadron, described by the Boer-Mulders TMD PDF. In the mid-1990's, Fermilab E-866/NuSea investigated angular distributions of p+p and p+d Drell-Yan and found that the relative strength of the cos (2 ϕ) modulation, as compared to pion-induced Drell-Yan, is reduced. Fermilab E-906/SeaQuest provides an ideal laboratory in which to measure the cos (2 ϕ) modulation at a higher target xBj than possible with E-866. Recent progress in the analysis of the angular distributions from SeaQuest Drell-Yan dimuons will be shown.
PREFACE: 1st Tensor Polarized Solid Target Workshop
NASA Astrophysics Data System (ADS)
2014-10-01
These are the proceedings of the first Tensor Spin Observables Workshop that was held in March 2014 at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. The conference was convened to study the physics that can be done with the recently approved E12-13-011 polarized target. A tensor polarized target holds the potential of initiating a new generation of tensor spin physics at Jefferson Lab. Experiments which utilize tensor polarized targets can help clarify how nuclear properties arise from partonic degrees of freedom, provide unique insight into short-range correlations and quark angular momentum, and also help pin down the polarization of the quark sea with a future Electron Ion Collider. This three day workshop was focused on tensor spin observables and the associated tensor target development. The workshop goals were to stimulate progress in the theoretical treatment of polarized spin-1 systems, foster the development of new proposals, and to reach a consensus on the optimal polarized target configuration for the tensor spin program. The workshop was sponsored by the University of New Hampshire, the Jefferson Science Associates, Florida International University, and Jefferson Lab. It was organized by Karl Slifer (chair), Patricia Solvignon, and Elena Long of the University of New Hampshire, Douglas Higinbotham and Christopher Keith of Jefferson Lab, and Misak Sargsian of the Florida International University. These proceedings represent the effort put forth by the community to begin exploring the possibilities that a high-luminosity, high-tensor polarized solid target can offer.
PARTON BUBBLE MODEL FOR TWO PARTICLE ANGULAR CORRELATIONS AT RHIC/LHC.
LINDENBAUM S.J.; LONGACRE, R.S.
2006-06-27
In an earlier paper we developed a bubble model, based on a view we had shared with van Hove for over two decades. Namely, that if a quark-gluon plasma is produced in a high energy heavy ion collider, then its hadronization products would likely be emitted from small bubbles localized in phase space containing plasma. In this paper we refined the model to become a parton bubble model in which each localized bubble contains initially 3-4 partons which are almost entirely gluons forming a gluon hot spot. We greatly expanded the transverse momentum interval investigated, and thus are able to treat recombination effects within each bubble. We again utilize two particle correlations as a sensitive method for detecting the average bubble substructure. In this manuscript we make many predictions for angular correlations detectable at RHIC and which will be later modified to LHC conditions. Some early available low precision correlation analyses is qualitatively explained. However a critical consistency test of the model can be made with high precision data expected in the near future.
Hard scattering of partons as a probe of collisions at RHIC using the STAR detector system
Christie, W.B.
1995-07-15
Presented here is the current state of the author`s investigations into the use of hard probes to study pp, pA, and AA collisions at the Relativistic Heavy Ion Collider (RHIC) being built at Brookhaven National Laboratory. The overall goal of the RHIC program is the discovery and study of the Quark-Gluon Plasma (QGP), which is predicted to be formed at the high energy densities reached at RHIC in high energy AA collisions. The term {open_quotes}Hard probes{close_quotes} as used in this document includes those particles whose origin is the result of a direct hard parton scatter (i.e qq, qg, or gg). The final states of these hard parton scatters which the author proposes to study include dijets, gamma-jet coincidences, and inclusive high P{sub t} particle spectra. A brief discussion of the physics objectives is given in section 1. This is followed by an introduction to the STAR detector system in section 2, with particular details given for the proposed STAR Electromagnetic Calorimeter (EMC). The present simulation studies and results are given in section 3. The author concludes with a summary and a discussion of future plans in section 4.
ERIC Educational Resources Information Center
Parr, Susan Resneck
1991-01-01
On college campuses, the climate is polarized because of intolerance and discrimination, censorship, factionalism, and anger among students and faculty. As a result, the campus is in danger of becoming dominated by political issues and discouraging the exchange of ideas characteristic of a true liberal arts education. (MSE)
Polar Rain Gradients and Field-Aligned Polar Cap Potentials
NASA Technical Reports Server (NTRS)
Fairfield, D. H.; Wing, S.; Newell, P. T.; Ruohoniemi, J. M.; Gosling, J. T.; Skoug, R. M.
2008-01-01
ACE SWEPAM measurements of solar wind field-aligned electrons have been compared with simultaneous measurements of polar rain electrons precipitating over the polar cap and detected by DMSP spacecraft. Such comparisons allow investigation of cross-polarcap gradients in the intensity of otherwise-steady polar rain. The generally good agreement of the distribution functions, f, from the two data sources confirms that direct entry of solar electrons along open field lines is indeed the cause of polar rain. The agreement between the data sets is typically best on the side of the polar cap with most intense polar rain but the DMSP f's in less intense regions can be brought into agreement with ACE measurements by shifting all energies by a fixed amounts that range from tens to several hundred eV. In most cases these shifts are positive which implies that field-aligned potentials of these amounts exist on polar cap field lines which tend to retard the entry of electrons and produce the observed gradients. These retarding potentials undoubtedly appear in order to prevent the entry of low-energy electrons and maintain charge quasi-neutrality that would otherwise be violated since most tailward flowing magnetosheath ions are unable to follow polar rain electrons down to the polar cap. In more limited regions near the boundary of the polar cap there is sometimes evidence for field-aligned potentials of the opposite sign that accelerate polar rain electrons. A solar electron burst is also studied and it is concluded that electrons from such bursts can enter the magnetotail and precipitate in the same manner as polar rain.
NASA Astrophysics Data System (ADS)
Petruk, Oleh; Bandiera, Rino; Beshley, Vasyl; Orlando, Salvatore; Miceli, Marco
2016-06-01
Polarized radio emission has been mapped with great details in several Galactic supernova remnants (SNRs). The polarization of synchrotron emission contains a wealth of information but has not yet been exploited to the extent it deserves. We have developed a numerical method to model the maps of the Stokes parameters for SNRs during their adiabatic phase of evolution, in either a uniform or a non-uniform environment. The method consists in the following steps. 1. A 3-dimensional magneto-hydrodynamical structure of the SNR is simulated, taking into account the interstellar magnetic field, and a possible gradient of the ISM density and/or of the ambient magnetic field. 2. The acceleration of particles at the forward shock and their evolution downstream are modelled. 3. The generation and dissipation of the turbulent component of magnetic field has been calculated everywhere in the SNR, taking into account its interaction with the accelerated particles. 4. Our generalization of the classical synchrotron theory, to include both the ordered and the disordered components of magnetic field, is used to model the emission. 5. The internal Faraday rotation of the polarization plane is considered. 6. Finally, 2-D maps are derived, for different orientations of the SNR with respect to the observer. We present details of the model, as well as some results of the numerical simulations.
Marchetti, Alfred P.; Haskins, Terri L.; Young, Ralph H.; Rothberg, Lewis J.
2014-03-21
Vapor-deposited Alq{sub 3} layers typically possess a strong permanent electrical polarization, whereas NPB layers do not. (Alq{sub 3} is tris(8-quinolinolato)aluminum(III); NPB is 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl.) The cause is a net orientation of the Alq{sub 3} molecules with their large dipole moments. Here we report on consequences for an organic light-emitting diode (OLED) with an NPB hole-transport layer and Alq{sub 3} electron-transport layer. The discontinuous polarization at the NPB|Alq{sub 3} interface has the same effect as a sheet of immobile negative charge there. It is more than compensated by a large concentration of injected holes (NPB{sup +}) when the OLED is running. We discuss the implications and consequences for the quantum efficiency and the drive voltage of this OLED and others. We also speculate on possible consequences of permanent polarization in organic photovoltaic devices. The concentration of NPB{sup +} was measured by charge-modulation spectroscopy (CMS) in the near infrared, where the NPB{sup +} has a strong absorption band, supplemented by differential-capacitance and current-voltage measurements. Unlike CMS in the visible, this method avoids complications from modulation of the electroluminescence and electroabsorption.
NASA Astrophysics Data System (ADS)
Batyunya, B. V.; Boguslavsky, I. V.; Gramenitsky, I. M.; Lednický, R.; Levonian, S. V.; Tikhonova, L. A.; Valkárová, A.; Vrba, V.; Zlatanov, Z.; Boos, E. G.; Samoilov, V. V.; Takibaev, Zh. S.; Temiraliev, T.; Lichard, P.; Mašejová, A.; Dumbrajs, S.; Ervanne, J.; Hannula, E.; Villanen, P.; Dementiev, R. K.; Korzhavina, I. A.; Leikin, E. M.; Rud, V. I.; Herynek, I.; Reimer, P.; Řídký, J.; Sedlák, J.; Šimák, V.; Suk, M.; Khudzadze, A. M.; Kuratashvili, G. O.; Topuriya, T. P.; Tzintzadze, V. D.
1980-03-01
We compare the inclusive characteristics ofbar pp interactions at 22.4 GeV/ c with quark-parton model predictions in terms of collective variables. The model qualitatively agrees with the data in contradiction to the simple cylindrical phase space and randomized charge model. The ways are proposed of a further development of the quark-parton model.
Asaturyan, R.; Ent, R.; Mkrtchyan, H.; ...
2012-01-01
A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W',more » is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π+ and π-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.« less
Degree of polarization of type-II unpolarized light
Luis, Alfredo
2007-05-15
We address a quantitative determination of the degree of polarization of type-II unpolarized light via the computation of the distance between the polarization distribution and the uniform distribution associated with fully unpolarized light (i.e., type-I unpolarized light or natural light). We determine the maximum degree of polarization for type-II unpolarized light and the states reaching it. We show that the degree of polarization can be arbitrarily large, approaching complete polarization for increasing mean photon numbers.
NASA Technical Reports Server (NTRS)
2006-01-01
3 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed by erosion in a trough within the north polar residual cap of Mars, diving beneath a younger covering of polar materials. The layers have, since the Mariner 9 mission in 1972, been interpreted to be composed of a combination of dust and ice in unknown proportions. In this scene, a layer of solid carbon dioxide, which was deposited during the previous autumn and winter, blankets the trough as well as the adjacent terrain. Throughout northern spring, the carbon dioxide will be removed; by summer, the layers will be frost-free.
Location near: 81.4oN, 352.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring
Romereim, Sarah M
2011-01-01
Despite extensive genetic analysis of the dynamic multi-phase process that transforms a small population of lateral plate mesoderm into the mature limb skeleton, the mechanisms by which signaling pathways regulate cellular behaviors to generate morphogenetic forces are not known. Recently, a series of papers have offered the intriguing possibility that regulated cell polarity fine-tunes the morphogenetic process via orienting cell axes, division planes and cell movements. Wnt5a-mediated non-canonical signaling, which may include planar cell polarity, has emerged as a common thread in the otherwise distinct signaling networks that regulate morphogenesis in each phase of limb development. These findings position the limb as a key model to elucidate how global tissue patterning pathways direct local differences in cell behavior that, in turn, generate growth and form. PMID:22064549
Bachy, Charles; López-García, Purificación; Vereshchaka, Alexander; Moreira, David
2011-01-01
Our knowledge about the microorganisms living in the high Arctic Ocean is still rudimentary compared to other oceans mostly because of logistical challenges imposed by its inhospitable climate and the presence of a multi-year ice cap. We have used 18S rRNA gene libraries to study the diversity of microbial eukaryotes in the upper part of the water column (0-170 m depth), the sea ice (0-1.5 m depth) and the overlying snow from samples collected in the vicinity of the North Pole (N88°35', E015°59) at the very end of the long polar night. We detected very diverse eukaryotes belonging to Alveolata, Fungi, Amoebozoa, Viridiplantae, Metazoa, Rhizaria, Heterokonta, and Telonemia. Different alveolates (dinoflagellates and Marine Alveolate Groups I and II species) were the most abundant and diverse in gene libraries from water and sea ice, representing 80% of the total number of clones and operational taxonomic units. Only contaminants and/or species from continental ecosystems were detected in snow, suggesting wind- and animal- or human-mediated cosmopolitan dispersal of some taxa. By contrast, sea ice and seawater samples harbored a larger and more similar inter-sample protist diversity as compared with snow. The North Pole was found to harbor distinctive eukaryotic communities along the vertical gradient with an unparalleled diversity of core dinoflagellates, largely dominant in libraries from the water column, as compared to other oceanic locations. In contrast, phototrophic organisms typical of Arctic sea ice and plankton, such as diatoms and prasinophytes, were very rare in our samples. This was most likely due to a decrease of their populations after several months of polar night darkness and to the presence of rich populations of diverse grazers. Whereas strict phototrophs were scarce, we identified a variety of likely mixotrophic taxa, which supports the idea that mixotrophy may be important for the survival of diverse protists through the long polar night.