Transverse-momentum-dependent gluon distributions from JIMWLK evolution
NASA Astrophysics Data System (ADS)
Marquet, C.; Petreska, E.; Roiesnel, C.
2016-10-01
Transverse-momentum-dependent (TMD) gluon distributions have different operator definitions, depending on the process under consideration. We study that aspect of TMD factorization in the small- x limit, for the various unpolarized TMD gluon distributions encountered in the literature. To do this, we consider di-jet production in hadronic collisions, since this process allows to be exhaustive with respect to the possible operator definitions, and is suitable to be investigated at small x. Indeed, for forward and nearly back-to-back jets, one can apply both the TMD factorization and Color Glass Condensate (CGC) approaches to compute the di-jet cross-section, and compare the results. Doing so, we show that both descriptions coincide, and we show how to express the various TMD gluon distributions in terms of CGC correlators of Wilson lines, while keeping N c finite. We then proceed to evaluate them by solving the JIMWLK equation numerically. We obtain that at large transverse momentum, the process dependence essentially disappears, while at small transverse momentum, non-linear saturation effects impact the various TMD gluon distributions in very different ways. We notice the presence of a geometric scaling regime for all the TMD gluon distributions studied: the "dipole" one, the Weizsäcker-Williams one, and the six others involved in forward di-jet production.
The gluon Sivers distribution: Status and future prospects
Boer, Daniël; Lorcé, Cédric; Pisano, Cristian; ...
2015-06-28
In this study, we review what is currently known about the gluon Sivers distribution and what are the opportunities to learn more about it. Because single transverse spin asymmetries in p↑p → πX provide only indirect information about the gluon Sivers function through the relation with the quark-gluon and tri-gluon Qiu-Sterman functions, current data from hadronic collisions at RHIC have not yet been translated into a solid constraint on the gluon Sivers function.
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.
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.
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.
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.
QCD Factorization, Wilson Loop Space and Unintegrated Gluon Distributions
NASA Astrophysics Data System (ADS)
Cherednikov, Igor O.
2017-03-01
Currently available operator definitions of gauge-invariant unintegrated (transverse momentum dependent) gluon density function available are briefly overviewed, with emphasis on the structure of the associated Wilson lines. A gauge-invariant generating function with maximal path-dependence is proposed, which, as distinct from the common methodology, is based on arbitrary Wilson loops with no reference to any factorization scheme. After the local area differentiation defined in the Wilson loop space, this object can be used to define fully unintegrated gluon distribution functions in a way potentially suitable for the lattice simulations.
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.
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.
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
Lipatov, A. V.
2006-09-15
The inclusive production of heavy quarks and quarkonia in photon-photon collisions at the LEP2 collider is considered within the semihard (k{sub T}-factorization) QCD approach. The dependence of the total and differential cross sections for the production of heavy (c and b) quarks and D* and J/{psi} mesons on the choice of unintegrated gluon distribution is studied. The transition of a cc-bar charmed pair to observed J/{psi} mesons is described on the basis of the color-singlet model. The results of the calculations are compared with currently available experimental data obtained by the L3, OPAL, ALEPH, and DELPHI Collaborations. It is shown that the polarization properties of J/{psi} mesons at the LEP2 collider are sensitive to the behavior of unintegrated gluon distributions. This means that experimental investigations of the polarization properties of quarkonia in photon-photon collisions may provide a direct test of the dynamics of gluon distributions in the photon.
NASA Astrophysics Data System (ADS)
Mehrabi Pari, Sharareh; Javidan, Kurosh; Taghavi Shahri, Fatemeh
2016-05-01
The "Laplace Transform Method" is used to solve the Fokker-Plank equation for finding the time evolution of the heavy quarks distribution functions such as charm and bottom in quark gluon plasma. These solutions will lead us to calculation of nuclear suppression factor RAA. The results have good agreement with available experiment data from the PHENIX collaboration.
Rapidity distribution of photons from an anisotropic quark-gluon plasma
Bhattacharya, Lusaka; Roy, Pradip
2010-05-15
We calculate rapidity distribution of photons due to Compton and annihilation processes from quark gluon plasma with pre-equilibrium momentum-space anisotropy. We also include contributions from hadronic matter with late-stage transverse expansion. A phenomenological model has been used for the time evolution of hard momentum scale, p{sub hard}(tau), and anisotropy parameter, xi(tau). As a result of pre-equilibrium momentum-space anisotropy, we find significant modification of photons rapidity distribution. For example, with the fixed initial condition (FIC) free-streaming (delta=2) interpolating model we observe significant enhancement of photon rapidity distribution at fixed p{sub T}, where as for FIC collisionally broadened (delta=2/3) interpolating model the yield increases till yapprox1. Beyond that suppression is observed. With fixed final multiplicity (FFM) free-streaming interpolating model we predict enhancement of photon yield which is less than the case of FIC. Suppression is always observed for FFM collisionally broadened interpolating model.
Weiler, T.
1981-10-01
An overview is presented of the attributes of gluons, deducible from experimental data. Particular attention is given to the photon-gluon fusion model of charm leptoproduction. The agreement with QCD and theoretical prejudice is qualitatively good.
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.
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%.
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). .
Heavy Flavour Production as Probe of Gluon Sivers Function
NASA Astrophysics Data System (ADS)
Godbole, Rohini M.; Kaushik, Abhiram; Misra, Anuradha; Rawoot, Vaibhav; Sonawane, Bipin
2017-03-01
Heavy flavour production like J/ψ and D-meson production in scattering of electrons/unpolarized protons off polarized proton target offer promising probes to investigate gluon Sivers function. In this talk, I will summarize our recent work on transverse single spin asymmetry in J/ψ -production and D-meson production in p p^\\uparrow scattering using a generalized parton model approach. We compare predictions obtained using different models of gluon Sivers function within this approach and then, taking into account the transverse momentum dependent evolution of the unpolarized parton distribution functions and gluon Sivers function, we study the effect of evolution on asymmetry.
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.
Gluon TMDs in Quarkonium Production
NASA Astrophysics Data System (ADS)
Boer, Daniël
2017-03-01
Quarkonium production offers good possibilities to study gluon TMDs. In this proceedings contribution this topic is explored for the linearly polarized gluons inside unpolarized hadrons and unpolarized gluons inside transversely polarized hadrons. It is argued that χ _{b0/2} and η _b production at LHC are best to study the effects of linearly polarized gluons in hadronic collisions, by means of angular independent ratios of ratios of cross sections. This can be directly compared to cos 2φ asymmetries in heavy quark pair and dijet production in DIS at a future high-energy Electron-Ion Collider (EIC), which probe the same TMDs. In the small- x limit this corresponds to the Weizsäcker-Williams (WW) gluon distributions, which should show a change in behavior for transverse momenta around the saturation scale. Together with investigations of the dipole (DP) gluon distributions, this can provide valuable information about the polarization of the Color Glass Condensate if sufficiently small x-values are reached. Quarkonia can also be useful in the study of single transverse spin asymmetries. For transversely polarized hadrons the gluon distribution can be asymmetric, which is referred to as the Sivers effect. It leads to single spin asymmetries in for instance J{/}ψ (pair) production at AFTER@LHC, which probe the WW or f-type gluon Sivers TMD. It allows for a test of a sign-change relation w.r.t. the gluon Sivers TMD probed at an EIC in open heavy quark pair production. Single spin asymmetries in backward inclusive C-odd quarkonium production, such as J{/}ψ production, may offer probes of the DP or d-type gluon Sivers TMD at small x-values in the polarized proton, which in that limit corresponds to a correlator of a single Wilson loop, describing the spin-dependent odderon.
NASA Astrophysics Data System (ADS)
Boroun, G. R.; Rezaie, B.
2008-06-01
We present a set of formulas using the solution of the QCD Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation to extract of the exponents of the gluon distribution, λ g , and structure function, λ S , from the Regge-like behavior at low x. The exponents are found to be independent of x and to increase linearly with ln Q 2 and are compared with the most data from the H1 Collaboration. We also calculated the structure function F 2( x,Q 2) and the gluon distribution G( x,Q 2) at low x assuming the Regge-like behavior of the gluon distribution function at this limit and compared them with an NLO-QCD fit to theH1 data, two-Pomeron fit, multipole Pomeron exchange fit, and MRST (A.D. Martin, R.G. Roberts, W.J. Stirling, and R.S. Thorne), DL (A. Donnachie and P.V. Landshoff), and NLO GRV (M. Glük, E. Reya, and A. Vogt) fit results.
Image processing methods to obtain symmetrical distribution from projection image.
Asano, H; Takenaka, N; Fujii, T; Nakamatsu, E; Tagami, Y; Takeshima, K
2004-10-01
Flow visualization and measurement of cross-sectional liquid distribution is very effective to clarify the effects of obstacles in a conduit on heat transfer and flow characteristics of gas-liquid two-phase flow. In this study, two methods to obtain cross-sectional distribution of void fraction are applied to vertical upward air-water two-phase flow. These methods need projection image only from one direction. Radial distributions of void fraction in a circular tube and a circular-tube annuli with a spacer were calculated by Abel transform based on the assumption of axial symmetry. On the other hand, cross-sectional distributions of void fraction in a circular tube with a wire coil whose conduit configuration rotates about the tube central axis periodically were measured by CT method based on the assumption that the relative distributions of liquid phase against the wire were kept along the flow direction.
LHC soft physics and transverse momentum dependent gluon density at low x
NASA Astrophysics Data System (ADS)
Lipatov, A. V.; Lykasov, G. I.; Zotov, N. P.
2014-01-01
We study the unintegrated, or transverse momentum dependent gluon distribution obtained from the best description of the LHC data on the inclusive spectra of hadrons produced in the midrapidity region and at low transverse momenta at the starting scale Q02=1 GeV2. To extend this gluon density to higher Q2 we apply the Catani-Ciafoloni-Fiorani-Marchesini evolution equation. The influence of the initial (starting) nonperturbative gluon distribution is studied. The application of the obtained gluon density to the analysis of the deep inelastic ep scattering allows us to get the results which describe reasonably well the H1 and ZEUS data on the longitudinal proton structure function FL(x ,Q2). So, the connection between the soft processes at the LHC and small-x physics at HERA has been confirmed and extended to a wide kinematical region.
NASA Astrophysics Data System (ADS)
Guzey, V.; Strikman, M.; Zhalov, M.
2017-02-01
By using the theoretical approaches that describe well the available data on t -integrated coherent photoproduction of light and heavy vector mesons in Pb-Pb ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) in Run 1, we calculate the momentum transfer distributions for this process for ρ and J /ψ vector mesons in the kinematics of Run 2 at the LHC. We demonstrate that nuclear shadowing not only suppresses the absolute value of the cross sections but also shifts the momentum transfer distributions toward smaller values of the momentum transfer |t | . This result can be interpreted as a broadening in the impact parameter space of the effective nucleon density in nuclei by 14% in the case of ρ and the nuclear gluon distribution by 5%-11% in the case of J /ψ .
Silicon distribution on the lunar surface obtained by Kaguya GRS
NASA Astrophysics Data System (ADS)
Kim, Kyeong Ja; Kobayashi, Masanori; Elphic, Richard; Karouji, Yuzuru; Hamara, Dave; Kobayashi, Shingo; Nagaoka, Hiroshi; Rodriguez, Alexis; Yamashita, Naoyuki; Reedy, Robert; Hasebe, Nobuyuki
Gamma ray spectrometry (GRS) provides a powerful tool to map and characterize the elemental composition of the upper tens centimeters of solid planetary surfaces. Elemental maps generated by the Kaguya GRS (KGRS) include natural radioactive as well as major elements maps (e.g., Fe, Ca, and Ti). Analysis of the Si gamma ray has been investigated using the 4934 keV Si peak produced by the thermal neutron interaction (28) Si(n,gammag) (29) Si, generated during the interaction of galactic cosmic rays and surface material containing Si. The emission rate of gamma rays is directly proportional to the abundance of Si from the lunar surface; however, it is also affected by the thermal neutron density in the lunar surface. Thus, we corrected the Si GRS data by a low energy neutron data (< 0.1 eV) obtained by Lunar Prospector because the Kaguya orbiter did not carry a neutron detector. We used the relative change in thermal neutron flux as a function of topography measured by Lunar Prospector. Normalization of Si elemental abundance using the Kaguya data was accomplished using Apollo 11, 12, 16, and 17 archive data. The normalized Si elemental abundance of the Kaguya GRS data ranged from about 15 to 27% Si. The lowest and highest SiO _{2} abundance correspond to mineral groups like pyroxene group (PKT region) and feldspar group (Northern highlands), respectively. The Si abundance permits the quantification of the relative abundance and distribution of mafic or non-mafic lunar surfaces materials. Our KGRS data analysis shows that highland terrains are Si-enriched relative to lower basins and plains regions, which appear to consist of primarily of mafic rocks. Our elemental map of Si using Kaguya GRS data shows that the highland areas of both near side and far side of the Moon have higher abundance of Si, and the mare regions of the near side of the Moon have the lowest Si abundance on the Moon. Our study clearly shows that there are a number of Si enriched areas compared to
Enhanced Usage of Keys Obtained by Physical, Unconditionally Secure Distributions
NASA Astrophysics Data System (ADS)
Kish, Laszlo B.; Granqvist, Claes-Göran
2015-04-01
Unconditionally secure physical key distribution schemes are very slow, and it is practically impossible to use a one-time-pad based cipher to guarantee unconditional security for the encryption of data because using the key bits more than once gives out statistical information, for example via the known-plain-text-attack or by utilizing known components of the protocol and language statistics. Here, we outline a protocol that reduces this speed problem and allows almost-one-time-pad based communication with an unconditionally secure physical key of finite length. The physical, unconditionally secure key is not used for data encryption but is employed in order to generate and share a new software-based key without any known-plain-text component. The software-only-based key distribution is then changed from computationally secure to unconditionally secure, because the communicated key-exchange data (algorithm parameters, one-way functions of random numbers, etc.) are encrypted in an unconditionally secure way with a one-time-pad. For practical applications, this combined physical/software key distribution based communication looks favorable compared to the software-only and physical-only key distribution based communication whenever the speed of the physical key distribution is much lower than that of the software-based key distribution. A mathematical security proof of this new scheme remains an open problem.
A simple approximation method for obtaining the spanwise lift distribution
NASA Technical Reports Server (NTRS)
Schrenk, O
1940-01-01
The approximation method described makes possible lift-distribution computations in a few minutes. Comparison with an exact method shows satisfactory agreement. The method is of greater applicability than the exact method and includes also the important case of the wing with end plates.
Gluon saturation in a saturated environment
Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan
2011-07-15
A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q{sub sA}{sup 2}, in AA compared with pA collisions.
Gluon TMDs in Quarkonium Production
NASA Astrophysics Data System (ADS)
Signori, Andrea
2016-08-01
I report on our investigations into the impact of (un)polarized transverse momentum dependent parton distribution functions (TMD PDFs or TMDs) for gluons at hadron colliders, especially at A Fixed Target Experiment at the LHC (AFTER@LHC). In the context of high energy proton-proton collisions, we look at final states with low mass (e.g. η _b) in order to investigate the nonperturbative part of TMD PDFs. We study the factorization theorem for the q_T spectrum of η _b produced in proton-proton collisions relying on the effective field theory approach, defining the tools to perform phenomenological investigations at next-to-next-to-leading log and next-to-leading order accuracy in the perturbation theory. We provide predictions for the unpolarized cross section and comment on the possibility of extracting nonperturbative information about the gluon content of the proton once data at low transverse momentum are available.
Quarks and gluons at hadron colliders
Bodek, A.; CDF Collaboration
1996-08-01
Data from proton-antiproton collisions at high energy provide important information on constraining the quark and gluon distributions in the nucleon and place limits on quark substructure. The S asymmetry data constrains the slope of the d/u quark distributions and significantly reduces the systematic error on the extracted value of the W mass. Drell-Yan data at high invariant mass provides strong limits on quark substructure. Information on {alpha}{sub s} and the gluon distributions can be extracted from high P{sub T} jet data and direct photons.
Gluon Evolution and Saturation Proceedings
McLerran, L.D.
2010-05-26
Almost 40 years ago, Gribov and colleagues at the Leningrad Nuclear Physics Institute developed the ideas that led to the Dokhsitzer-Gribov-Altarelli-Parisi the Baltisky-Fadin-Kuraev-Lipatov equations. These equations describe the evolution of the distributions for quarks and gluon inside a hadron to increased resolution scale of a probe or to smaller values of the fractional momentum of a hadronic constituent. I motivate and discuss the generalization required of these equations needed for high energy processes when the density of constituents is large. This leads to a theory of saturation realized by the Color Glass Condensate
Amplitude for N-gluon superstring scattering.
Stieberger, Stephan; Taylor, Tomasz R
2006-11-24
We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope alpha'. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in alpha', for the so-called maximally helicity violating configurations, with N = 4, 5 and N = 6. We also obtain the leading O(alpha '2) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.
Amplitude for N-Gluon Superstring Scattering
Stieberger, Stephan; Taylor, Tomasz R.
2006-11-24
We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope {alpha}{sup '}. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in {alpha}{sup '}, for the so-called maximally helicity violating configurations, with N=4, 5 and N=6. We also obtain the leading O({alpha}{sup '2}) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.
Constituent gluons and the static quark potential
Greensite, Jeff; Szczepaniak, Adam P.
2016-04-01
We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.
Gluon TMD in particle production from low to moderate x
Balitsky, I.; Tarasov, A.
2016-06-28
We study the rapidity evolution of gluon transverse momentum dependent distributions appearing in processes of particle production and show how this evolution changes from small to moderate Bjorken x.
Rapidity evolution of gluon TMD from low to moderate x
Balitsky, Ian; Tarasov, A.
2015-10-05
In this article, we study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small $x \\ll 1$ to linear evolution at moderate $x \\sim 1$.
Rapidity evolution of gluon TMD from low to moderate x
Balitsky, Ian; Tarasov, A.
2015-10-05
In this article, we study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at smallmore » $$x \\ll 1$$ to linear evolution at moderate $$x \\sim 1$$.« less
Theoretical distribution of range data obtained by laser radar and its applications
NASA Astrophysics Data System (ADS)
Haijiao, Jiang; Jiancheng, Lai; Wei, Yan; Chunyong, Wang; Zhenhua, Li
2013-02-01
This paper addresses the distribution of range data obtained by laser radar. An analytical solution of the range distribution was obtained for direct detection laser radar using constant threshold discriminator based on the time-of-flight principle. The analytical solution was verified by experiments and simulations. The results show that the derived analytical function can describe the probability density distribution of the range data obtained by laser radar with a constant threshold discriminator. The probability density distribution of the range data is proportional to the probability density function of the noise and to the slope of the rising edge of the laser echo pulse. The probability density distributions of the range data obtained by laser radar with different pulse shapes, amplitudes, widths and thresholds are also presented. These factors are important for improvements in the design of laser radar systems.
NASA Astrophysics Data System (ADS)
Chala, Mikael; Juknevich, José; Perez, Gilad; Santiago, José
2015-01-01
We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bounds on its mass can be up to 2TeV milder than in the simpler models considered so far for the LHC14. We discuss the origin of this difference and prospects for dedicated searches.
Ayala, A.L.; Ducati, M.B.G.; Levin, E.M.
1996-10-01
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.
The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion
Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin
2016-11-15
Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-Nc master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluon expansionmore » therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of αslog. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of αslog from the coefficients of the fixed order expansion.« less
The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion
Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin
2016-11-15
Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-N_{c} master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluon expansion therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of α_{s}log. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of α_{s}log from the coefficients of the fixed order expansion.
The gluon condensation at high energy hadron collisions
NASA Astrophysics Data System (ADS)
Zhu, Wei; Lan, Jiangshan
2017-03-01
We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing-antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton-proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron-hadron colliders.
NASA Technical Reports Server (NTRS)
Moore, H. J.; Wu, S. C.
1973-01-01
The effect of reading error on two hypothetical slope frequency distributions and two slope frequency distributions from actual lunar data in order to ensure that these errors do not cause excessive overestimates of algebraic standard deviations for the slope frequency distributions. The errors introduced are insignificant when the reading error is small and the slope length is large. A method for correcting the errors in slope frequency distributions is presented and applied to 11 distributions obtained from Apollo 15, 16, and 17 panoramic camera photographs and Apollo 16 metric camera photographs.
Technology Transfer Automated Retrieval System (TEKTRAN)
By testing a tapered fiber beard, certain fiber length parameters can be obtained rapidly. This study is aimed at exploring the possibility to obtain the entire length distribution of a sample from the beard test method. In Part 1, the mathematical function describing cotton fiber length was searc...
Lincoln, Don
2015-05-07
Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilab’s Dr. Don Lincoln explains the hottest known state of matter – a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.
Lincoln, Don
2016-07-12
Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilabâs Dr. Don Lincoln explains the hottest known state of matter â a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.
Quark and Gluon Relaxation in Quark-Gluon Plasmas
NASA Technical Reports Server (NTRS)
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
Recent COMPASS results on the gluon polarization
Quintans, Catarina
2009-03-23
The spin structure of the nucleon is studied in the COMPASS experiment at CERN/SPS, from the collisions of 160 GeV polarized muon beam with a {sup 6}LiD target. The data collected from 2002 to 2006 provide an accurate measurement of longitudinal double spin cross-section asymmetries. The latest results on the gluon polarization, accessed from two independent analyses of photon-gluon fusion selected events, are presented. The study of the open-charm production allows to extract the gluon polarization (in LO QCD) from the measurement of the asymmetry, the value obtained being {delta}g/g -0.49{+-}0.27(stat){+-}0.11(syst), at an average x{sub g} 0.11{sub -0.05}{sup +0.11} and a scale <{mu}{sup 2}> = 13(GeV/c){sup 2}. An alternative and independent way to study the gluon polarization, by studying the high transverse momentum hadron pairs produced, leads to a value {delta}g/g 0.08{+-}0.10(stat){+-}0.05(syst), at x{sub g}{sup a{nu}} 0.082{sub -0.027}{sup +0.041} and <{mu}{sup 2}> = 3(GeV/c){sup 2}.
Gluon fragmentation functions in the Nambu-Jona-Lasinio model
NASA Astrophysics Data System (ADS)
Yang, Dong-Jing; Li, Hsiang-nan
2016-09-01
We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by treating a gluon as a pair of color lines formed by a fictitious quark and antiquark (q q ¯). Gluon elementary fragmentation functions are obtained from the quark and antiquark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the q q ¯ pair maintains in the flavor-singlet state after meson emissions. An integral equation, which iterates the gluon elementary fragmentation functions to all orders, is then solved to yield the gluon fragmentation functions at a model scale. It is observed that these solutions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improves the agreement with the SLD data for the pion and kaon productions in e+e- annihilation. Our proposal provides a plausible construct for the gluon fragmentation functions, which are supposed to be null in the NJL model.
Dissociation of heavy quarkonia in the quark-gluon plasma
NASA Astrophysics Data System (ADS)
Wong, Cheuk-Yin
2002-09-01
Using a temperature-dependent potential obtained from lattice gauge calculations of Karsch et al, we study the stability of heavy quarkonia in the quark-gluon plasma. We find that only the Υ(1S) and ηb(1S) are bound in the quark-gluon plasma, and have a small binding energy. The quark-gluon plasma may be revealed by an Υ(1S) dilepton peak with an invariant mass close to twice the current b quark mass, which is lower than the Υ(1S) mass in free space. The quarkonia Υ(1S) and ηb(1S) can dissociate by collision with quarks and gluons in the quark-gluon plasma. The Υ(1S) and the ηb(1S) can also dissociate spontaneously at temperatures above the dissociation temperature 1.11 Tc, where Tc is the quark-gluon plasma phase transition temperature. At temperatures slightly above the dissociation temperature these states appear as resonances, which provides another signature for the quark-gluon plasma.
Schwinger-Dyson Equations and Dynamical gluon mass generation
Aguilar, A.C.; Natale, A.A.
2004-12-02
We obtain a solution for the gluon propagador in Landau gauge within two distinct approximations for the Schwinger-Dyson equations (SDE). The first, named Mandelstam's approximation, consist in neglecting all contributions that come from fermions and ghosts fields while in the second, the ghosts fields are taken into account leading to a coupled system of integral equations. In both cases we show that a dynamical mass for the gluon propagator can arise as a solution.
Technology Transfer Automated Retrieval System (TEKTRAN)
The beard testing method for measuring cotton fiber length is based on the fibrogram theory. However, in the instrumental implementations, the engineering complexity alters the original fiber length distribution observed by the instrument. This causes challenges in obtaining the entire original le...
Quarks and gluons in hadrons and nuclei
Close, F.E. Tennessee Univ., Knoxville, TN )
1989-12-01
These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs.
Abeykoon M.; Billinge S.; Malliakas, C.D.; Juhas, P.; Bozin, E.S.; Kanatzidis, M.G.
2012-05-01
Quantitatively reliable atomic pair distribution functions (PDFs) have been obtained from nanomaterials in a straightforward way from a standard laboratory transmission electron microscope (TEM). The approach looks very promising for making electron derived PDFs (ePDFs) a routine step in the characterization of nanomaterials because of the ubiquity of such TEMs in chemistry and materials laboratories. No special attachments such as energy filters were required on the microscope. The methodology for obtaining the ePDFs is described as well as some opportunities and limitations of the method.
Dmitriev, A; Kuznetsov, S; Shavrin, P; Lyagushin, V; Nechaev, O; Panasyuk, M; Tolstaya, E; Nikiforova, M
1998-01-01
A set of instruments for measuring energetic particle fluxes, containing two neutron detectors under different plexiglas shielding thicknesses, a scintillation detector, measuring energy release >0.1 MeV and 0.5 MeV and a Geiger counter were launched onboard OS 'MIR'. The latitude dependencies of the cosmic ray measurements were obtained and studied. The distributions of primary particle fluxes (protons and elections) as well as secondary particle fluxes (bremsstrahlung gamma-rays and neutrons) produced in interactions of radiation belt particles with the station materials were obtained. The electron belt, generated during the storm of March 24 1991, is studied.
Neutron angular distribution in a plasma focus obtained using nuclear track detectors.
Castillo-Mejía, F; Herrera, J J E; Rangel, J; Golzarri, J I; Espinosa, G
2002-01-01
The dense plasma focus (DPF) is a coaxial plasma gun in which a high-density, high-temperature plasma is obtained in a focused column for a few nanoseconds. When the filling gas is deuterium, neutrons can be obtained from fusion reactions. These are partially due to a beam of deuterons which are accelerated against the background hot plasma by large electric fields originating from plasma instabilities. Due to a beam-target effect, the angular distribution of the neutron emission is anisotropic, peaked in the forward direction along the axis of the gun. The purpose of this work is to illustrate the use of CR-39 nuclear track detectors as a diagnostic tool in the determination of the time-integrated neutron angular distribution. For the case studied in this work, neutron emission is found to have a 70% contribution from isotropic radiation and a 30% contribution from anisotropic radiation.
NASA Technical Reports Server (NTRS)
Cintala, Mark J.; Mcbride, Kathleen M.
1995-01-01
Among the hazards that must be negotiated by lunar-landing spacecraft are blocks on the surface of the Moon. Unfortunately, few data exist that can be used to evaluate the threat posed by such blocks to landing spacecraft. Perhaps the best information is that obtained from Surveyor photographs, but those data do not extend to the dimensions of the large blocks that would pose the greatest hazards. Block distributions in the vicinities of the Surveyor 1, 3, 6, and 7 sites have been determined from Lunar Orbiter photography and are presented here. Only large (i.e., greater than or equal to 2.5 m) blocks are measurable in these pictures, resulting in a size gap between the Surveyor and Lunar Orbiter distributions. Nevertheless, the orbital data are self-consistent, a claim supported by the similarity in behavior between the subsets of data from the Surveyor 1, 3, and 6 sites and by the good agreement in position (if not slopes) between the data obtained from the Surveyor 3 photography and those derived from the Lunar Orbiter photographs. Confidence in the results is also justified by the well-behaved distribution of large blocks at the surveyor site. Comparisons between the Surveyor distributions and those derived from the orbital photography permit these observations: (1) in all cases but that for Surveyor 3, the density of large blocks is overestimated by extrapolation of the Surveyor-derived trends; (2) the slopes of the Surveyor-derived distributions are consistently lower than those determined for the large blocks; and (3) these apparent disagreements could be mitigated if the overall shapes of the cumulative lunar block populations were nonlinear, allowing for different slopes over different size intervals. The relatively large gaps between the Surveyor-derived and Orbiter-derived data sets, however, do not permit a determination of those shapes.
NASA Technical Reports Server (NTRS)
Takeda, K.; Ochiai, H.; Takeuchi, S.
1985-01-01
Maximum snow water equivalence and snowcover distribution are estimated using several LANDSAT data taken in snowmelting season over a four year period. The test site is Okutadami-gawa Basin located in the central position of Tohoku-Kanto-Chubu District. The year to year normalization for snowmelt volume computation on the snow line is conducted by year to year correction of degree days using the snowcover percentage within the test basin obtained from LANDSAT data. The maximum snow water equivalent map in the test basin is generated based on the normalized snowmelt volume on the snow line extracted from four LANDSAT data taken in a different year. The snowcover distribution on an arbitrary day in snowmelting of 1982 is estimated from the maximum snow water equivalent map. The estimated snowcover is compared with the snowcover area extracted from NOAA-AVHRR data taken on the same day. The applicability of the snow estimation using LANDSAT data is discussed.
Global Ring Current Ion Distributions Obtained by IMAGE/HENA DURING STORMS AND SUBSTORMS
NASA Astrophysics Data System (ADS)
Brandt, P. C.; Ganushkina, N.; Zheng, Y.; Fok, M.; Mitchell, D. G.; Demajistre, R.; Roelof, E. C.
2005-05-01
Global Energetic Neutral Atom (ENA) images of the Hydrogen and Oxygen ring current in the 10-200 keV range have been obtained by IMAGE/HENA for five years. Approximately 40 storms have been succesfully imaged. Over the years a constrained linear inversion technique has been developed that can retrieve the equatorial ring current ion distributions from the ENA images. It uses the Tsyganenko [2003] magnetic field model and assumes pitch-angle distributions based on in-situ data. We investigate the general morphology of the ring current during storm times with special attention to the question of how much the storm-time substorm injections contribute to the ring current pressure. We discuss and compare observations with ring current models.
SUePDF: a program to obtain quantitative pair distribution functions from electron diffraction data
Tran, Dung Trung; Svensson, Gunnar; Tai, Cheuk-Wai
2017-01-01
SUePDF is a graphical user interface program written in MATLAB to achieve quantitative pair distribution functions (PDFs) from electron diffraction data. The program facilitates structural studies of amorphous materials and small nanoparticles using electron diffraction data from transmission electron microscopes. It is based on the physics of electron scattering as well as the total scattering methodology. A method of background modeling is introduced to treat the intensity tail of the direct beam, inelastic scattering and incoherent multiple scattering. Kinematical electron scattering intensity is scaled using the electron scattering factors. The PDFs obtained after Fourier transforms are normalized with respect to number density, nanoparticle form factor and the non-negativity of probability density. SUePDF is distributed as free software for academic users. PMID:28190994
Equilibration in quark gluon plasma
NASA Astrophysics Data System (ADS)
Das, S. K.; Alam, J.; Mohanty, P.
2011-07-01
The hydrodynamic expansion rate of quark gluon plasma (QGP) is evaluated and compared with the scattering rate of quarks and gluons within the system. Partonic scattering rates evaluated within the ambit of perturbative Quantum Choromodynamics (pQCD) are found to be smaller than the expansion rate evaluated with ideal equation of state (EoS) for the QGP. This indicate that during the space-time evolution the system remains out of equilibrium. Enhancement of pQCD cross sections and a more realistic EoS keep the partons closer to the equilibrium.
NASA Technical Reports Server (NTRS)
Schneider, Harold
1959-01-01
This method is investigated for semi-infinite multiple-slab configurations of arbitrary width, composition, and source distribution. Isotropic scattering in the laboratory system is assumed. Isotropic scattering implies that the fraction of neutrons scattered in the i(sup th) volume element or subregion that will make their next collision in the j(sup th) volume element or subregion is the same for all collisions. These so-called "transfer probabilities" between subregions are calculated and used to obtain successive-collision densities from which the flux and transmission probabilities directly follow. For a thick slab with little or no absorption, a successive-collisions technique proves impractical because an unreasonably large number of collisions must be followed in order to obtain the flux. Here the appropriate integral equation is converted into a set of linear simultaneous algebraic equations that are solved for the average total flux in each subregion. When ordinary diffusion theory applies with satisfactory precision in a portion of the multiple-slab configuration, the problem is solved by ordinary diffusion theory, but the flux is plotted only in the region of validity. The angular distribution of neutrons entering the remaining portion is determined from the known diffusion flux and the remaining region is solved by higher order theory. Several procedures for applying the numerical method are presented and discussed. To illustrate the calculational procedure, a symmetrical slab ia vacuum is worked by the numerical, Monte Carlo, and P(sub 3) spherical harmonics methods. In addition, an unsymmetrical double-slab problem is solved by the numerical and Monte Carlo methods. The numerical approach proved faster and more accurate in these examples. Adaptation of the method to anisotropic scattering in slabs is indicated, although no example is included in this paper.
NASA Technical Reports Server (NTRS)
Cintala, Mark J.; Mcbride, Kathleen M.
1994-01-01
Enlargements of Lunar-Orbiter photography were used in conjunction with a digitizing tablet to collect the locations and dimensions of blocks surrounding the Surveyor 1, 3, 6, and 7 landing sites. Data were reduced to the location and the major axis of the visible portion of each block. Shadows sometimes made it difficult to assess whether the visible major axis corresponded with the actual principal dimension. These data were then correlated with the locations of major craters in the study areas, thus subdividing the data set into blocks obviously associated with craters and those in intercrater areas. A block was arbitrarily defined to be associated with a crater when its location was within 1.1 crater radii of the crater's center. Since this study was commissioned for the ultimate purpose of determining hazards to landing spacecraft, such a definition was deemed appropriate in defining block-related hazards associated with craters. Size distributions of smaller fragments as determined from Surveyor photography were obtained as measurements from graphical data. Basic comparisons were performed through use of cumulative frequency distributions identical to those applied to studies of crater-count data.
An effective encoding scheme of obtaining radial topology structures in distribution networks.
Wen, Juan; Tan, Yanghong; Zhang, Jianmin
2016-01-01
The structure of a distribution network has great effects on economy, power supply reliability and investment of a power system. To obtain an optimal topology from possible topologies, we need to solve an optimisation problem which aims to find a radial structure satisfying operating constraints. As a basis of solving this optimisation problem, the encoding scheme, is to represent the candidate configurations by a series of codes. Numerical candidate topologies and unfeasible codes would lead low efficiency or premature convergence. This paper presents an effective scheme which can rapidly produce all radial configurations of a distribution network. In order to reduce the computational requirement of solution space, initial network is simplified as a topological graph which reserves loop branches and T-nodes. And a loop-branch chain incidence matrix is derived from analyzing the relationship between any two loops. Then the principles of selecting switches of each variable are designed to determine the ranges of the variables. All radial candidate solutions are available rapidly through applying the theory of combination. The scheme presented minimizes the number of solutions and avoids tedious radial checking procedure in view of avoiding any infeasible solutions. The validity of the proposed scheme is verified by illustrative examples.
NASA Astrophysics Data System (ADS)
Ling, Tong; Yang, Yongying; Liu, Dong; Yue, Xiumei; Jiang, Jiabin
2015-10-01
A wavefront retrieval method for the quadriwave lateral shearing interferogram obtained by randomly encoded hybrid grating (REHG) is proposed. The REHG consists of a binary amplitude grating and a phase chessboard, and the Faunhofer diffractions of this grating only contain the +/-1 orders in two orthogonal directions. As a result, no order selection mask is ever needed by the REHG for quadriwave lateral shearing interference. To retrieve the phase distributions from the REHG interferograms, fast Fourier transform (FFT) technique is employed at first to get the frequency spectrum. By performing inverse fast Fourier transform (IFFT) of the +1 order spectrum in the x and y directions, it is possible to extract shearing wavefronts from the interferogram in both two orthogonal directions. Using the translation property of Fourier transform, the relationship between the Fourier spectrum of the shearing wavefronts and the Fourier spectrum of the wavefront under test is deduced. The wavefront under test is retrieved by establishing an evaluation function firstly and finding the minimum value with least-square-solution. Analysis and compensations are made to reduce the errors in the testing results. Simulation experiments have shown that this method can retrieve different phase distributions without losing high-frequency information.
The evolution of the small x gluon TMD
NASA Astrophysics Data System (ADS)
Zhou, Jian
2016-06-01
We study the evolution of the small x gluon transverse momentum dependent (TMD) distribution in the dilute limit. The calculation has been carried out in the Ji-Ma-Yuan scheme using a simple quark target model. As expected, we find that the resulting small x gluon TMD simultaneously satisfies both the Collins-Soper (CS) evolution equation and the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution equation. We thus confirmed the earlier finding that the high energy factorization (HEF) and the TMD factorization should be jointly employed to resum the different type large logarithms in a process where three relevant scales are well separated.
On effects of multiple gluons in J/ψ hadroproduction
Motyka, Leszek; Sadzikowski, Mariusz
2015-04-10
The three-gluon contribution to J/ψ hadroproduction is calculated within perturbative QCD in the k{sub T}-factorization framework. This mechanism involves double gluon density and enters at a non-leading twist, but it is enhanced at large energies due to large double gluon density at small x. We obtain results for differential p{sub T}-dependent cross-sections for all J/ψ polarisations. The rescattering contribution is found to provide a significant correction to the standard leading twist cross-section at the energies of the Tevatron or the LHC at moderate p{sub T}. We also discuss a possible contribution of the rescattering correction to the anti-shadowing effect for J/ψ production in proton - nucleus collisions.
Worldline calculation of the three-gluon vertex
Ahmadiniaz, N.; Schubert, C.
2012-10-23
The three-gluon vertex is a basic object of interest in nonabelian gauge theory. At the one-loop level, it has been calculated and analyzed by a number of authors. Here we use the worldline formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in terms of field strength tensors. We verify its equivalence with previously obtained representations, and explain the relation of its structure to the low-energy effective action. The sum rule found by Binger and Brodsky for the scalar, spinor and gluon loop contributions in the present approach relates to worldline supersymmetry.
NASA Astrophysics Data System (ADS)
Denton, Cristian D.; Moreno-Marín, Juan Carlos; Heredia-Avalos, Santiago
2015-06-01
The idea of using carbon nanotubes (CNTs) as masks against irradiation has recently emerged, because of the region of a given material covered by a CNT can be protected from the effects of irradiation, creating nanowires. In this case, it is interesting to know in detail the number of generated recoils and their energy. In order to obtain these data, we simulate the irradiation of CNTs with carbon ions using a molecular dynamics code. To describe the interaction between carbon ions we use the Brenner potential joined smoothly to the Universal ZBL potential at short distances. We have analyzed the energy distributions of the carbon atoms emerging from the CNT for single projectile irradiation with incident energies from 30 eV to 5 keV. Our results show that the number and the energy of the recoil carbon atoms emerging from the CNT increases with the projectile incident energy. In average, each projectile with incident energy of 1 keV produces ∼3.6 recoils, which have a mean energy of 150 eV, while projectiles with 5 keV produce ∼7 recoils with a mean energy of 400 eV.
LPM Interference and Cherenkov-like Gluon Bremsstrahlung in DenseMatter
Majumder, Abhijit; Wang, Xin-Nian
2005-07-26
Gluon bremsstrahlung induced by multiple parton scattering in a finite dense medium has a unique angular distribution with respect to the initial parton direction. A dead-cone structure with an opening angle; theta2{sub 0}; approx 2(1-z)/(zLE) for gluons with fractional energy z arises from the Landau-Pomeran chuck-Migdal (LPM) interference. In a medium where the gluon's dielectric constant is; epsilon>1, the LPM interference pattern is shown to become Cherenkov-like with an increased opening angle determined by the dielectric constant$/cos2/theta{sub c}=z+(1-z)//epsilon$. For a large dielectric constant/epsilon; gg 1+2/z2LE, the corresponding total radiative parton energy loss is about twice that from normal gluon bremsstrahlung. Implications of this Cherenkov-like gluon bremsstrahlung to the jet correlation pattern in high-energy heavy-ion collisions is discussed.
Bremsstrahlung from an equilibrating quark-gluon plasma
NASA Astrophysics Data System (ADS)
Mustafa, Munshi G.; Thoma, Markus H.
2000-07-01
The photon production rate from a chemically equilibrating quark-gluon plasma likely to be produced at RHIC (BNL) and LHC (CERN) energies is estimated taking into account bremsstrahlung. The plasma is assumed to be in local thermal equilibrium, but with a phase space distribution that deviates from the Fermi or Bose distribution by space-time dependent factors (fugacities). The photon spectrum is obtained by integrating the photon rate over the space-time history of the plasma, adopting a boost invariant cylindrically symmetric transverse expansion of the system with different nuclear profile functions. Initial conditions obtained from a self-screened parton cascade calculation and, for comparison, from the HIJING model are used. Compared to an equilibrated plasma at the same initial energy density, taken from the self-screened parton cascade, a moderate suppression of the photon yield by a factor of 1 to 5 depending on the collision energy and the photon momentum is observed. The individual contributions to the photon production, however, are completely different in the both scenarios.
NASA Astrophysics Data System (ADS)
Schenke, Björn; Schlichting, Sören; Tribedy, Prithwish; Venugopalan, Raju
2016-10-01
The mass ordering of mean transverse momentum ⟨pT⟩ and of the Fourier harmonic coefficient v2(pT) of azimuthally anisotropic particle distributions in high energy hadron collisions is often interpreted as evidence for the hydrodynamic flow of the matter produced. We investigate an alternative initial state interpretation of this pattern in high-multiplicity proton-proton collisions at the LHC. The QCD Yang-Mills equations describing the dynamics of saturated gluons are solved numerically with initial conditions obtained from the color-glass-condensate-based impact-parameter-dependent glasma model. The gluons are subsequently fragmented into various hadron species employing the well established Lund string fragmentation algorithm of the pythia event generator. We find that this initial state approach reproduces characteristic features of bulk spectra, in particular, the particle mass dependence of ⟨pT⟩ and v2(pT).
NASA Astrophysics Data System (ADS)
Benedetto, A.; Magazù, S.; Migliardo, F.; Mondelli, C.; Gonzalez, M. A.
2012-02-01
In the present contribution, a procedure for molecular motion characterization based on the evaluation of the Mean Square Displacement (MSD), through the Self-Distribution Function (SDF), is presented. It is shown how MSD, which represents an important observable for the characterization of dynamical properties, can be decomposed into different partial contributions associated to system dynamical processes within a specific spatial scale. It is also shown how the SDF procedure allows us to evaluate both total MSD and partial MSDs through total and partial SDFs. As a result, total MSD is the weighed sum of partial MSDs in which the weights are obtained by the fitting procedure of measured Elastic Incoherent Neutron Scattering (EINS) intensity. We apply SDF procedure to data collected,by IN13, IN10 and IN4 spectrometers (Institute Laue Langevin), on aqueous mixtures of two homologous disaccharides (sucrose and trehalose) and on dry and hydrated (H2O and D2O) lysozyme with and without disaccharides. It emerges that the hydrogen bond imposed network of the water-trehalose mixture appears to be stronger with respect to that of the water-sucrose mixture. This result can justify the higher bioprotectant effectiveness of trehalose. Furthermore, it emerges that partial MSDs of sucrose and trehalose are equivalent in the low Q domain (0÷1.7) Å-1 whereas they are different in the high Q domain (1.7÷4) Å-1. This suggests that the higher structure sensitivity of sucrose should be related to the small spatial observation windows. Moreover, the role of the instrumental resolution in EINS is considered. The nature of the dynamical transition is highlighted and it is shown that it occurs when the system relaxation time becomes shorter than the instrumental energy time. Finally, the bioprotectants effect on protein dynamics and the amplitude of vibrations in lysozyme are presented.
Semi-inclusive polarised lepton-nucleon scattering and the anomalous gluon contribution
NASA Astrophysics Data System (ADS)
Güllenstern, St.; Veltri, M.; Górnicki, P.; Mankiewicz, L.; Schäfer, A.
1993-08-01
We discuss a new observable for semi-inclusive pion production in polarised lepton-nucleon collisions. This observable is sensitive to the polarised and unpolarised strange quark distribution and the anomalous gluon contribution, provided that their fragmentation functions into pions differ substantially from that of light quarks. From Monte Carlo data generated with our PEPSI code we conclude that HERMES might be able to decide whether the polarized strange quark and gluon distributions are large.
Measurements of gluon spin-sensitive quantities at the Z{sup 0} resonance
Fan, C.G.
1993-10-01
Measurements have been made of the scaled jet energies (x{sub 1}, x{sub 2}, x{sub 3}) and the Ellis-Karliner angle (cos{theta}{sub EK}), which are sensitive to the spill of the gluon, in the 3-jet hadronic events from the e{sup +}e{sup {minus}} annihilation at the Z{sup 0} resonance. The experiment is performed with the SLD detector at the Stanford Linear Accelerator Center (SLAC). The data used in this analysis was collected during the 1992 physics run, which includes 10,252 hadronic Z{sup 0} events that have CDC information written out. Only charged tracks measured in the central drift chamber are used for the measurements of the above variables. The raw data are found to be in good agreement with the Monte Carlo simulations passing the same set of track and event selection cuts. A bin-to-bin correction is done for the distributions of x{sub 1}, x{sub 2}, x{sub 3}, and cos{theta}{sub EK} to account for the effects of hadronization, detector acceptance and resolution. The corrected data is compared to the parton level distributions of x{sub 1}, x{sub 2}, x{sub 3}, and cos{theta}{sub EK} simulated from the vector QCD model and the scalar gluon model respectively. The systematic errors, calculated for all the bins in these distributions, are obtained by comparing the results from different sets of track and event selection cuts, from different hadronization models and from different Monte Carlo programs. Good agreement is found between data and the vector QCD model. The scalar gluon model strongly disagrees with the data.
The gluon mass generation mechanism: A concise primer
NASA Astrophysics Data System (ADS)
Aguilar, A. C.; Binosi, D.; Papavassiliou, J.
2016-04-01
We present a pedagogical overview of the nonperturbative mechanism that endows gluons with a dynamical mass. This analysis is performed based on pure Yang-Mills theories in the Landau gauge, within the theoretical framework that emerges from the combination of the pinch technique with the background field method. In particular, we concentrate on the Schwinger-Dyson equation satisfied by the gluon propagator and examine the necessary conditions for obtaining finite solutions within the infrared region. The role of seagull diagrams receives particular attention, as do the identities that enforce the cancellation of all potential quadratic divergences.We stress the necessity of introducing nonperturbative massless poles in the fully dressed vertices of the theory in order to trigger the Schwinger mechanism, and explain in detail the instrumental role of these poles in maintaining the Becchi-Rouet-Stora-Tyutin symmetry at every step of the mass-generating procedure. The dynamical equation governing the evolution of the gluon mass is derived, and its solutions are determined numerically following implementation of a set of simplifying assumptions. The obtained mass function is positive definite, and exhibits a power law running that is consistent with general arguments based on the operator product expansion in the ultraviolet region. A possible connection between confinement and the presence of an inflection point in the gluon propagator is briefly discussed.
D-meson enhancement in pp collisions at the LHC due to nonlinear gluon evolution
Dainese, A.; Vogt, R.; Bondila, M.; Eskola, K.J.; Kolhinen, V.J.
2004-08-22
When nonlinear effects on the gluon evolution are included with constraints from HERA, the gluon distribution in the free proton is enhanced at low momentum fractions, x {approx}< 0.01, and low scales, Q{sup 2} {approx}< 10 GeV{sup 2}, relative to standard, DGLAP-evolved, gluon distributions. Consequently, such gluon distributions can enhance charm production in pp collisions at center of mass energy 14 TeV by up to a factor of five at midrapidity, y {approx} 0, and transverse momentum p{sub T} {yields} 0 in the most optimistic case. We show that most of this enhancement survives hadronization into D mesons. Assuming the same enhancement at leading and next-to-leading order, we show that the D enhancement may be measured by D{sup 0} reconstruction in the K{sup -}{pi}{sup +} decay channel with the ALICE detector.
Gluon Contribution To The Nucleon Spin
Arash, Firooz; Shahveh, Abolfazl; Taghavi-Shahri, Fatemeh
2011-07-15
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although {delta}g/g is small at the currently measured kinematics, it does not imply that the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, {Delta}g(Q{sup 2}), is sizable. We also notice that the majority of {Delta}g is concentrated at around x = 0.08.
Quark ACM with topologically generated gluon mass
NASA Astrophysics Data System (ADS)
Choudhury, Ishita Dutta; Lahiri, Amitabha
2016-03-01
We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( < 10 MeV), we calculate the ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.
NASA Technical Reports Server (NTRS)
Christoffersen, P. A.; Simon, Justin I.; Ross, D. K.; Friedrich, J. M.; Cuzzi, J. N.
2012-01-01
Size distributions of nebular solids in chondrites suggest an efficient sorting of these early forming objects within the protoplanetary disk. The effect of this sorting has been documented by investigations of modal abundances of CAIs (e.g., [1-4]) and chondrules (e.g., [5-8]). Evidence for aerodynamic sorting in the disk is largely qualitative, and needs to be carefully assessed. It may be a way of concentrating these materials into planetesimal-mass clumps, perhaps 100 fs of ka after they formed. A key parameter is size/density distributions of particles (i.e., chondrules, CAIs, and metal grains), and in particular, whether the radius-density product (rxp) is a better metric for defining the distribution than r alone [9]. There is no consensus between r versus rxp based models. Here we report our initial tests and preliminary results, which when expanded will be used to test the accuracy of current dynamical disk models.
Probing quark gluon plasma properties by heavy flavors
Das, Santosh K.; Alam, Jan-e; Mohanty, Payal
2009-11-15
The Fokker-Planck (FP) equation has been solved to study the interaction of nonequilibrated heavy quarks with the quark gluon plasma expected to be formed in heavy ion collisions at Relativistic Heavy Ion Collider energies. Solutions of the FP equation have been convoluted with the relevant fragmentation functions to obtain the D and B meson spectra. Results are compared with experimental data measured by the STAR Collaboration. It is found that the present experimental data cannot distinguish p{sub T} spectra obtained from the equilibrium versus the nonequilibrium charm distributions. Data at lower p{sub T} may play a crucial role in making the distinction between the two. The nuclear suppression factor R{sub AA} for nonphotonic single-electron spectra resulting from semileptonic decays of hadrons containing heavy flavors has been evaluated using the present formalism. It is observed that the experimental data on the nuclear suppression factor of nonphotonic electrons can be reproduced within this formalism by enhancing the perturbative QCD cross sections by a factor of 2, provided that the expansion of the bulk matter is governed by the velocity of sound c{sub s}{approx}1/{radical}(4). The ideal-gas equation of state fails to reproduce the data even with enhancement of the perturbative QCD cross sections by a factor of 2.
Virtual photon emission from a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Suryanarayana, S. V.
2007-10-01
We present phenomenological formulas for virtual photon emission rates from a thermalized quark-gluon plasma (QGP) that include bremsstrahlung and annihilation with scattering (AWS) mechanisms along with the Landau-Pomeranchuk-Migdal (LPM) effects. For this purpose we follow the approach of generalized emission functions (GEF) for virtual photon emission, we showed earlier for a fixed temperature and strong coupling constant. In the present work, we extend the LPM calculations for several temperatures and strong coupling strengths, photon energies (q0), photon mass (Q2), and quark energies (p0). We generalize the dynamical scaling variables, xT,xL, for bremsstrahlung and AWS processes that are now functions of variables p0,q0,Q2,T,αs. The GEF introduced earlier, gTb,gTa,gLb,gLa, are also generalized for any temperatures and coupling strengths. From this, the imaginary part of the photon polarization tensor as a function of photon mass and energy has been calculated as a one-dimensional integral over these GEF and parton distribution functions in the plasma. By fitting these polarization tensors obtained from GEF method, we obtained a phenomenological formula for virtual photon emission rates as a function of {q0,Q2,T,αs} that includes bremsstrahlung and AWS mechanisms with LPM effects.
Parametrization of the Transverse Momentum Dependent Light-Front Correlator for Gluons
NASA Astrophysics Data System (ADS)
Cotogno, Sabrina
2017-03-01
We study the transverse momentum dependent light-front correlator for gluons. At the operator level this is expressed as a matrix element containing nonlocal field strength operators and gauge links bridging the nonlocality. We parametrize the leading (twist-2) gluon-gluon correlator in terms of transverse momentum dependent distribution functions for unpolarized, vector and tensor polarized targets (the latter being relevant for spin-1 targets). For a tensor polarized target there are eleven functions among which two are time reversal odd. We discuss bounds on some functions which might become useful for future applications.
NASA Astrophysics Data System (ADS)
Bai, Jun; Shi, Zongqian; Jia, Shenli
2017-02-01
Numerical investigations on the formation process and the final size distribution of nanoparticles during electrical explosion of Al wire are carried out. Firstly, the formation of the atomic vapor clusters is investigated. It indicates that the Al wire does not reach its atomization conditions. The size of the atomic vapor clusters is obtained, and it increases with the temperature at explosion. Then the growth process of Al nanoparticles from the formed atomic vapor clusters is modeled and the size distribution is predicted. The size distribution at different temperatures indicates that the growth process of Al nanoparticles becomes inactive gradually as the temperature decreases. The investigation of the size distribution under different cooling rates indicates that the bigger cooling rate is favorable for the formation of Al nanoparticles with smaller size dispersion and lower average dimension. The size distribution of Al nanoparticles obtained by the model is qualitatively consistent with the experimental data, which demonstrates the feasibility of this model.
Ordering Multiple Soft Gluon Emissions
NASA Astrophysics Data System (ADS)
Ángeles Martínez, René; Forshaw, Jeffrey R.; Seymour, Michael H.
2016-05-01
We present an expression for the QCD amplitude for a general hard scattering process with any number of soft gluon emissions, to one-loop accuracy. The amplitude is written in two different but equivalent ways: as a product of operators ordered in dipole transverse momentum and as a product of loop-expanded currents. We hope that these results will help in the development of an all-orders algorithm for multiple emissions that includes the full color structure and both the real and imaginary contributions to the amplitude.
Mass distribution of meteoroids obtained by a meteor forward-scatter (MFS) radar method.
NASA Astrophysics Data System (ADS)
Cevolani, G.; Gabucci, M. F.
1996-04-01
The cumulative distributions of the number vs. duration of echoes belonging to main meteor showers (Lyrids, η-Aquarids, δ-Aquarids, Perseids, Orionids, Leonids, Geminids) and sporadic background were investigated using a forward-scatter (FS) continuous-wave meteor radar link operational during 1992 - 95 over the long baseline Bologna-Lecce in Italy. The trend of the mass distribution of particles in the quoted meteoroid streams was derived, and the values of the mass index s were compared for each meteor population with the steady-state condition. It was found that the mass index s generally increases towards long-duration echoes, but many of the observed meteor streams appear to have unstable populations. The values of the mass index of the sporadic complex are generally higher than the corresponding ones of meteor showers in the range of echo durations 0.1 ≤ T ≤ 10 s. This is a possible consequence of longer-lasting FS signals, indicating a shift of the mass distribution function vs. higher echo durations. Moreover, non-gravitational forces in connection with solar radiation pressure, Poynting-Robertson effect, solar-wind particle streaming, mutual collisions, etc., appear to be responsible for the observed widespread radiants and for unstable populations in the meteoroid streams.
NASA Astrophysics Data System (ADS)
Akimoto, Takuma; Yamamoto, Eiji
2016-12-01
Local diffusion coefficients in disordered systems such as spin glass systems and living cells are highly heterogeneous and may change over time. Such a time-dependent and spatially heterogeneous environment results in irreproducibility of single-particle-tracking measurements. Irreproducibility of time-averaged observables has been theoretically studied in the context of weak ergodicity breaking in stochastic processes. Here, we provide rigorous descriptions of equilibrium and non-equilibrium diffusion processes for the annealed transit time model, which is a heterogeneous diffusion model in living cells. We give analytical solutions for the mean square displacement (MSD) and the relative standard deviation of the time-averaged MSD for equilibrium and non-equilibrium situations. We find that the time-averaged MSD grows linearly with time and that the time-averaged diffusion coefficients are intrinsically random (irreproducible) even in the long-time measurements in non-equilibrium situations. Furthermore, the distribution of the time-averaged diffusion coefficients converges to a universal distribution in the sense that it does not depend on initial conditions. Our findings pave the way for a theoretical understanding of distributional behavior of the time-averaged diffusion coefficients in disordered systems.
The Radial Distribution Function (RDF) of Amorphous Selenium Obtained through the Vacuum Evaporator
Guda, Bardhyl; Dede, Marie
2010-01-21
After the amorphous selenium obtained through the vacuum evaporator, the relevant diffraction intensity is taken and its processing is made. Further on the interferential function is calculated and the radial density function is defined. For determining these functions are used two methods, which were compared with each other and finally are received results for amorphous selenium RDF.
Probing the Linear Polarization of Gluons in Unpolarized Hadrons at EIC
Boer, Daniel; Brodsky, Stanley J.; Mulders, Piet J.; Pisano, Cristian; /Cagliari U. /INFN, Cagliari
2011-08-17
Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this TMD distribution of linearly polarized gluons is through cos 2{phi} asymmetries in heavy quark pair or dijet production in electron-hadron collisions. Future EIC or LHeC experiments are ideally suited for this purpose. Here we estimate the maximum asymmetries for EIC kinematics.
Treaftis, H.N.; Kacsmar, P.; Suppers, K., Tomb, T.F.
1986-02-01
The paper discusses the results of a study conducted to evaluate two different methods used to measure the particle size distribution of an aerosol. Comparative samples were collected in the laboratory with Sierra's Models 260 and 298 cascade impaction samplers and a sampler consisting of a pump and filter using coal and limestone aerosols of varying particle size distributions. The particle size distributions determined from each of the impaction samples were compared to each other as well as to the particle size distribution determined from data obtained from a Coulter Counter analysis of the total dust sample collected on the filter. The results of the laboratory study are discussed and compared to a limited amount of similar data obtained from samples collected with the impaction samplers in underground coal mines.
Dimension-six triple gluon operator in Higgs +jet observables
NASA Astrophysics Data System (ADS)
Ghosh, Diptimoy; Wiebusch, Martin
2015-02-01
Recently a lot of progress has been made towards a full classification of new physics effects in Higgs observables by means of effective dimension-six operators. Specifically, Higgs production in association with a high transverse momentum jet has been suggested as a way to discriminate between operators that modify the Higgs-top coupling (Ot) and operators that induce an effective Higgs-gluon coupling (Og)—a distinction that is hard to achieve with signal strength measurements alone. With this article we would like to draw attention to another source of new physics in Higgs +jet observables: the triple gluon operator O3 g (consisting of three factors of the gluon field strength tensor). We compute the distortions of kinematic distributions in Higgs +jet production at a 14 TeV LHC due to O3 g and compare them with the distortions due to Ot and Og. We find that the transverse momentum distributions alone cannot discriminate between O3 g and Og if the coefficient of the operator Ot treated as an unknown parameter. We further show that the jet rapidity and the difference between the Higgs and jet rapidity are well suited to remove this new degeneracy. Using rough estimates for the expected bounds we find that allowed distortions in kinematic distributions due to Og are of similar size as those due to O3 g. We conclude that a full analysis of new physics in Higgs +jet observables must take the contributions from O3 g into account.
HUNTING THE QUARK GLUON PLASMA.
LUDLAM, T.; ARONSON, S.
2005-04-11
The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high
Weipeng, Wang; Jianli, Liu; Bingzi, Zhao; Jiabao, Zhang; Xiaopeng, Li; Yifan, Yan
2015-01-01
Mathematical descriptions of classical particle size distribution (PSD) data are often used to estimate soil hydraulic properties. Laser diffraction methods (LDM) now provide more detailed PSD measurements, but deriving a function to characterize the entire range of particle sizes is a major challenge. The aim of this study was to compare the performance of eighteen PSD functions for fitting LDM data sets from a wide range of soil textures. These models include five lognormal models, five logistic models, four van Genuchten models, two Fredlund models, a logarithmic model, and an Andersson model. The fits were evaluated using Akaike’s information criterion (AIC), adjusted R2, and root-mean-square error (RMSE). The results indicated that the Fredlund models (FRED3 and FRED4) had the best performance for most of the soils studied, followed by one logistic growth function extension model (MLOG3) and three lognormal models (ONLG3, ORLG3, and SHCA3). The performance of most PSD models was better for soils with higher silt content and poorer for soils with higher clay and sand content. The FRED4 model best described the PSD of clay, silty clay, clay loam, silty clay loam, silty loam, loam, and sandy loam, whereas FRED3, MLOG3, ONLG3, ORLG3, and SHCA3 showed better performance for most soils studied. PMID:25927441
Methods for obtaining true particle size distributions from cross section measurements
Lord, Kristina Alyse
2013-01-01
Sectioning methods are frequently used to measure grain sizes in materials. These methods do not provide accurate grain sizes for two reasons. First, the sizes of features observed on random sections are always smaller than the true sizes of solid spherical shaped objects, as noted by Wicksell [1]. This is the case because the section very rarely passes through the center of solid spherical shaped objects randomly dispersed throughout a material. The sizes of features observed on random sections are inversely related to the distance of the center of the solid object from the section [1]. Second, on a plane section through the solid material, larger sized features are more frequently observed than smaller ones due to the larger probability for a section to come into contact with the larger sized portion of the spheres than the smaller sized portion. As a result, it is necessary to find a method that takes into account these reasons for inaccurate particle size measurements, while providing a correction factor for accurately determining true particle size measurements. I present a method for deducing true grain size distributions from those determined from specimen cross sections, either by measurement of equivalent grain diameters or linear intercepts.
Separation of quark and gluon jets in high-p/sub T/ events
Sjoestrand, T.
1984-01-01
We suggest a procedure, based on the kinematics of qg-scattering in high-p/sub T/ events, whereby it is possible to obtain enriched samples of quark and gluon jets. At SppS energies this could be used to indicate whether quark and gluon jet fragmentation agree or not. At higher energies the application would rather be to study the differences in the parton cascades, i.e. jet substructure.
Evolution of gluon TMDs from small to moderate x
Tarasov, Andrey
2016-05-01
Recently we obtained an evolution equation of gluon TMDs, which addresses a problem of unification of different kinematic regimes. It describes evolution in the whole range of Bjorken $x_B$ and the whole range of transverse momentum $k_\\perp$. In this notes I study different limits of this evolution equation and show how it yields several well-known and some previously unknown results.
Next-to-leading-order QCD corrections to Higgs boson production plus three jets in gluon fusion.
Cullen, G; van Deurzen, H; Greiner, N; Luisoni, G; Mastrolia, P; Mirabella, E; Ossola, G; Peraro, T; Tramontano, F
2013-09-27
We report on the calculation of the cross section for Higgs boson production in association with three jets via gluon fusion, at next-to-leading-order (NLO) accuracy in QCD, in the infinite top-mass approximation. After including the complete NLO QCD corrections, we observe a strong reduction in the scale dependence of the result, and an increased steepness in the transverse momentum distributions of both the Higgs boson and the leading jets. The results are obtained with the combined use of GOSAM, SHERPA, and the MADDIPOLE-MADEVENT framework.
NASA Astrophysics Data System (ADS)
Hamieh, Salah; Letessier, Jean; Rafelski, Johann
2000-12-01
Lattice quantum chromodynamics results provide an opportunity to model, and extrapolate to finite baryon density, the properties of the quark-gluon plasma (QGP). Upon fixing the scale of the thermal coupling constant and vacuum energy to the lattice data, the properties of resulting QGP equations of state (EoS) are developed. We show that the physical properties of the dense matter fireball formed in heavy ion collision experiments at CERN-SPS are well described by the QGP-EoS we presented. We also estimate the properties of the fireball formed in early stages of nuclear collision, and argue that QGP formation must be expected down to 40A GeV in central Pb-Pb interactions.
NASA Technical Reports Server (NTRS)
Hacker, Paul T.
1956-01-01
An airborne cloud aeroscope by which droplet size, size distribution, and liquid-water content of clouds can be determined has been developed and tested in flight and in wind tunnels with water sprays. In this aeroscope the cloud droplets are continuously captured in a stream of oil, which Is then photographed by a photomicrographic camera. The droplet size and size distribution can be determined directly from the photographs. With the droplet size distribution known, the liquid-water content of the cloud can be computed from the geometry of the aeroscope, the airspeed, and the oil-flow rate. The aeroscope has the following features: Data are obtained semi-automatically, and permanent data are taken in the form of photographs. A single picture usually contains a sufficient number of droplets to establish the droplet size distribution. Cloud droplets are continuously captured in the stream of oil, but pictures are taken at Intervals. The aeroscope can be operated in icing and non-icing conditions. Because of mixing of oil in the instrument, the droplet-distribution patterns and liquid-water content values from a single picture are exponentially weighted average values over a path length of about 3/4 mile at 150 miles per hour. The liquid-water contents, volume-median diameters, and distribution patterns obtained on test flights and in the Lewis icing tunnel are similar to previously published data.
A method for obtaining distributed surface flux measurements in complex terrain
NASA Astrophysics Data System (ADS)
Daniels, M. H.; Pardyjak, E.; Nadeau, D. F.; Barrenetxea, G.; Brutsaert, W. H.; Parlange, M. B.
2011-12-01
Sonic anemometers and gas analyzers can be used to measure fluxes of momentum, heat, and moisture over flat terrain, and with the proper corrections, over sloping terrain as well. While this method of obtaining fluxes is currently the most accurate available, the instruments themselves are costly, making installation of many stations impossible for most campaign budgets. Small, commercial automatic weather stations (Sensorscope) are available at a fraction of the cost of sonic anemometers or gas analyzers. Sensorscope stations use slow-response instruments to measure standard meteorological variables, including wind speed and direction, air temperature, humidity, surface skin temperature, and incoming solar radiation. The method presented here makes use of one sonic anemometer and one gas analyzer along with a dozen Sensorscope stations installed throughout the Val Ferret catchment in southern Switzerland in the summers of 2009, 2010 and 2011. Daytime fluxes are calculated using Monin-Obukhov similarity theory in conjunction with the surface energy balance at each Sensorscope station as well as at the location of the sonic anemometer and gas analyzer, where a suite of additional slow-response instruments were co-located. Corrections related to slope angle were made for wind speeds and incoming shortwave radiation measured by the horizontally-mounted cup anemometers and incoming solar radiation sensors respectively. A temperature correction was also applied to account for daytime heating inside the radiation shield on the slow-response temperature/humidity sensors. With these corrections, we find a correlation coefficient of 0.77 between u* derived using Monin-Obukhov similarity theory and that of the sonic anemometer. Calculated versus measured heat fluxes also compare well and local patterns of latent heat flux and measured surface soil moisture are correlated.
Glauber gluons in pion-induced Drell-Yan processes
NASA Astrophysics Data System (ADS)
Chang, Chun-peng; Li, Hsiang-nan
2013-10-01
We point out that the existence of Glauber gluons in the kT factorization theorem can account for the violation of the Lam-Tung relation, namely, the anomalous lepton angular distribution observed in pion-induced Drell-Yan processes. The emission of a final-state parton, that balances the lepton-pair transverse momentum, causes the responsible spin-transverse-momentum correlation in the Glauber-gluon background. It is argued that the Glauber effect is significant in the pion due to its unique role of being a Nambu-Goldstone boson and a qqbar bound state simultaneously. This mechanism is compared to other resolutions in the literature by means of vacuum effects and Boer-Mulders functions. We propose to discriminate the above resolutions by measuring the ppbar Drell-Yan process at GSI and J-PARC.
Abelian non-global logarithms from soft gluon clustering
NASA Astrophysics Data System (ADS)
Kelley, Randall; Walsh, Jonathan R.; Zuberi, Saba
2012-09-01
Most recombination-style jet algorithms cluster soft gluons in a complex way. This leads to previously identified correlations in the soft gluon phase space and introduces logarithmic corrections to jet cross sections, which are known as clustering logarithms. The leading Abelian clustering logarithms occur at least at next-to leading logarithm (NLL) in the exponent of the distribution. Using the framework of Soft Collinear Effective Theory (SCET), we show that new clustering effects contributing at NLL arise at each order. While numerical resummation of clustering logs is possible, it is unlikely that they can be analytically resummed to NLL. Clustering logarithms make the anti-kT algorithm theoretically preferred, for which they are power suppressed. They can arise in Abelian and non-Abelian terms, and we calculate the Abelian clustering logarithms at O ( {α_s^2} ) for the jet mass distribution using the Cambridge/Aachen and kT algorithms, including jet radius dependence, which extends previous results. We find that clustering logarithms can be naturally thought of as a class of non-global logarithms, which have traditionally been tied to non-Abelian correlations in soft gluon emission.
Gluon and Ghost Dynamics from Lattice QCD
NASA Astrophysics Data System (ADS)
Oliveira, O.; Duarte, A. G.; Dudal, D.; Silva, P. J.
2017-03-01
The two point gluon and ghost correlation functions and the three gluon vertex are investigated, in the Landau gauge, using lattice simulations. For the two point functions, we discuss the approach to the continuum limit looking at the dependence on the lattice spacing and volume. The analytical structure of the propagators is also investigated by computing the corresponding spectral functions using an implementation of the Tikhonov regularisation to solve the integral equation. For the three point function we report results when the momentum of one of the gluon lines is set to zero and discuss its implications.
Gluons and the NJL coupling constant
Braghin, Fábio L.; Barros Jr, Ednaldo; Paulo Jr, Ademar
2014-11-11
The QCD origin of the NJL model is re-analysed by considering the gluon condensate of order two . The key point is the treatment of the gluon interactions. To linearize the action the auxiliary variable method is employed to introduce a scalar variable φ(x) that yield such condensate by means of its value in the vacuum, and then another auxiliary variable that corresponds to an antisymmetric gluon configuration φ(x). For that, besides that, two different possible limits of the fourth order non local quark interaction that may contribute to the NJL coupling are compared.
Gluons and the NJL coupling constant
NASA Astrophysics Data System (ADS)
Braghin, Fábio L.; Barros, Ednaldo, Jr.; Paulo, Ademar, Jr.
2014-11-01
The QCD origin of the NJL model is re-analysed by considering the gluon condensate of order two . The key point is the treatment of the gluon interactions. To linearize the action the auxiliary variable method is employed to introduce a scalar variable φ(x) that yield such condensate by means of its value in the vacuum, and then another auxiliary variable that corresponds to an antisymmetric gluon configuration φ(x). For that, besides that, two different possible limits of the fourth order non local quark interaction that may contribute to the NJL coupling are compared.
Graviton and Gluon Scattering from First Principles.
Boels, Rutger H; Medina, Ricardo
2017-02-10
Graviton and gluon scattering are studied from minimal physical assumptions such as Poincare and gauge symmetry as well as unitarity. The assumptions lead to an interesting and surprisingly restrictive set of linear equations. This shows gluon and graviton scattering to be related in many field and string theories, explaining and extending several known results. By systematic analysis exceptional graviton scattering amplitudes are derived, which in general dimensions cannot be related to gluon amplitudes. The simplicity of the formalism guarantees wide further applicability to gauge and gravity theories.
On the zero crossing of the three-gluon vertex
NASA Astrophysics Data System (ADS)
Athenodorou, A.; Binosi, D.; Boucaud, Ph.; De Soto, F.; Papavassiliou, J.; Rodríguez-Quintero, J.; Zafeiropoulos, S.
2016-10-01
We report on new results on the infrared behavior of the three-gluon vertex in quenched Quantum Chromodynamics, obtained from large-volume lattice simulations. The main focus of our study is the appearance of the characteristic infrared feature known as 'zero crossing', the origin of which is intimately connected with the nonperturbative masslessness of the Faddeev-Popov ghost. The appearance of this effect is clearly visible in one of the two kinematic configurations analyzed, and its theoretical origin is discussed in the framework of Schwinger-Dyson equations. The effective coupling in the momentum subtraction scheme that corresponds to the three-gluon vertex is constructed, revealing the vanishing of the effective interaction at the exact location of the zero crossing.
Nonperturbative equation of state of quark gluon plasma: Applications
NASA Astrophysics Data System (ADS)
Komarov, E. V.; Simonov, Yu. A.
2008-05-01
The vacuum-driven nonperturbative factors Li for quark and gluon Green's functions are shown to define the nonperturbative dynamics of QGP in the leading approximation. EoS obtained recently in the framework of this approach is compared in detail with known lattice data for μ = 0 including P/ T4, ɛ/ T4, {ɛ-3P}/{T4}. The basic role in the dynamics at T ≲ 3 Tc is played by the factors Li which are approximately equal to the modulus of Polyakov line for quark Lfund and gluon Ladj. The properties of Li are derived from field correlators and compared to lattice data, in particular the Casimir scaling property Ladj=(Lfund) follows in the Gaussian approximation valid for small vacuum correlation lengths. Resulting curves for P/ T4, ɛ/ T4, {ɛ-3P}/{T4} are in a reasonable agreement with lattice data, the remaining difference points out to an effective attraction among QGP constituents.
Dynamical chiral symmetry with an infrared finite gluon propagator
NASA Astrophysics Data System (ADS)
Cardona, J. C.; Aguilar, A. C.
2016-04-01
In this work we study dynamical quark mass generation using an infrared finite gluon propagator obtained from quenched lattice simulations. The quark gap equation is solved using a purely non-Abelian Ansatz for the quark-gluon vertex, which displays a dependence on the ghost dressing function and the scalar component of quark-ghost scattering kernel. For the former quantity we use quenched lattice results, while for the latter we derive its own integral equation at the one-loop-dressed approximation. This latter quantity is then coupled to the system of equations governing the two Dirac structures of the quark propagator. It turns out that when a current quark mass of 5 MeV is introduced, the constituent quark mass generated from the gap equation is of the order of 310 MeV. In addition, the pion decay constant computed from the resulting quark propagator is in good agreement with the physical value.
Strong-coupling effects in a plasma of confining gluons
NASA Astrophysics Data System (ADS)
Florkowski, Wojciech; Ryblewski, Radoslaw; Su, Nan; Tywoniuk, Konrad
2016-12-01
The plasma consisting of confining gluons resulting from the Gribov quantization of the SU(3) Yang-Mills theory is studied using non-equilibrium fluid dynamical framework. Exploiting the Bjorken symmetry and using linear response theory a general analytic expressions for the bulk, ζ, and shear, η, viscosity coefficients are derived. It is found that the considered system exhibits a number of properties similar to the strongly-coupled theories, where the conformality is explicitly broken. In particular, it is shown that, in the large temperature limit, ζ / η ratio, scales linearly with the difference 1 / 3 - cs2, where cs is the speed of sound. Results obtained from the analysis are in line with the interpretation of the quark-gluon plasma as an almost perfect fluid.
NASA Technical Reports Server (NTRS)
Peterson, Harold; Koshak, William J.
2009-01-01
An algorithm has been developed to estimate the altitude distribution of one-meter lightning channel segments. The algorithm is required as part of a broader objective that involves improving the lightning NOx emission inventories of both regional air quality and global chemistry/climate models. The algorithm was tested and applied to VHF signals detected by the North Alabama Lightning Mapping Array (NALMA). The accuracy of the algorithm was characterized by comparing algorithm output to the plots of individual discharges whose lengths were computed by hand; VHF source amplitude thresholding and smoothing were applied to optimize results. Several thousands of lightning flashes within 120 km of the NALMA network centroid were gathered from all four seasons, and were analyzed by the algorithm. The mean, standard deviation, and median statistics were obtained for all the flashes, the ground flashes, and the cloud flashes. One-meter channel segment altitude distributions were also obtained for the different seasons.
Transport properties of quark and gluon plasmas
Heiselberg, H.
1993-12-01
The kinetic properties of relativistic quark-gluon and electron-photon plasmas are described in the weak coupling limit. The troublesome Rutherford divergence at small scattering angles is screened by Debye screening for the longitudinal or electric part of the interactions. The transverse or magnetic part of the interactions is effectively screened by Landau damping of the virtual photons and gluons transferred in the QED and QCD interactions respectively. Including screening a number of transport coefficients for QCD and QED plasmas can be calculated to leading order in the interaction strength, including rates of momentum and thermal relaxation, electrical conductivity, viscosities, flavor and spin diffusion of both high temperature and degenerate plasmas. Damping of quarks and gluons as well as color diffusion in quark-gluon plasmas is, however, shown not to be sufficiently screened and the rates depends on an infrared cut-off of order the ``magnetic mass,`` m{sub mag} {approximately} g{sup 2}T.
NASA Technical Reports Server (NTRS)
Holbrook, G. T.; Dunham, D. M.
1985-01-01
Detailed pressure distribution measurements were made for 11 twist configurations of a unique, multisegmented wing model having an aspect ratio of 7 and a taper ratio of 1. These configurations encompassed span loads ranging from that of an untwisted wing to simple flapped wings both with and without upper-surface spoilers attached. For each of the wing twist configurations, electronic scanning pressure transducers were used to obtain 580 surface pressure measurements over the wing in about 0.1 sec. Integrated pressure distribution measurements compared favorably with force-balance measurements of lift on the model when the model centerbody lift was included. Complete plots and tabulations of the pressure distribution data for each wing twist configuration are provided.
Hadrons and Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Letessier, Jean; Rafelski, Johann
2002-06-01
Before matter as we know it emerged, the universe was filled with the primordial state of hadronic matter called quark gluon plasma. This hot soup of quarks and gluon is effectively an inescapable consequence of our current knowledge about the fundamental hadronic interactions, quantum chromodynamics. This book covers the ongoing search to verify this prediction experimentally and discusses the physical properties of this novel form of matter.
Two-gluon rapidity correlations of strong colour field in pp, pA and AA collisions
NASA Astrophysics Data System (ADS)
Zhao, Ye-Yin; Xu, Ming-Mei; Zhang, Heng-Ying; Wu, Yuan-Fang
2016-11-01
Using the CGC formalism, we calculate the two-gluon rapidity correlations of strong colour fields in pp, pA and AA collisions, respectively. If one trigger gluon is fixed at central rapidity, a ridge-like correlation pattern is obtained in symmetry pp and AA collisions, and a huge bump-like correlation pattern is presented in asymmetry pA collisions. It is demonstrated that long-range ridge-like rapidity correlations are caused by the stronger correlation with the gluon of colour source. These features are independent of the azimuthal angular of two selected gluon. They are qualitatively consistent with current observed data at LHC. The transverse momentum and incident energy dependence of the ridge and bump-like correlations are also systematically studied. The ridge is more likely observed at higher incident energy and lower transverse momentum of trigger gluon.
High gluon densities in heavy ion collisions
NASA Astrophysics Data System (ADS)
Blaizot, Jean-Paul
2017-03-01
The early stages of heavy ion collisions are dominated by high density systems of gluons that carry each a small fraction x of the momenta of the colliding nucleons. A distinguishing feature of such systems is the phenomenon of ‘saturation’ which tames the expected growth of the gluon density as the energy of the collision increases. The onset of saturation occurs at a particular transverse momentum scale, the ‘saturation momentum’, that emerges dynamically and that marks the onset of non-linear gluon interactions. At high energy, and for large nuclei, the saturation momentum is large compared to the typical hadronic scale, making high density gluons amenable to a description with weak coupling techniques. This paper reviews some of the challenges faced in the study of such dense systems of small x gluons, and of the progress made in addressing them. The focus is on conceptual issues, and the presentation is both pedagogical, and critical. Examples where high gluon density could play a visible role in heavy ion collisions are briefly discussed at the end, for illustration purpose.
Precision Determination of the Small-x Gluon from Charm Production at LHCb
NASA Astrophysics Data System (ADS)
Gauld, Rhorry; Rojo, Juan
2017-02-01
The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-of-mass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c.m. values, R13 /7 and R13 /5. We demonstrate that forward charm production leads to a reduction of the PDF uncertainties of the gluon down to x ≃10-6 by up to an order of magnitude, with implications for high-energy colliders, cosmic ray physics, and neutrino astronomy.
Precision Determination of the Small-x Gluon from Charm Production at LHCb.
Gauld, Rhorry; Rojo, Juan
2017-02-17
The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-of-mass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c.m. values, R_{13/7} and R_{13/5}. We demonstrate that forward charm production leads to a reduction of the PDF uncertainties of the gluon down to x≃10^{-6} by up to an order of magnitude, with implications for high-energy colliders, cosmic ray physics, and neutrino astronomy.
Modeling Quark Gluon Plasma Using CHIMERA
NASA Astrophysics Data System (ADS)
Abelev, Betty
2011-09-01
We attempt to model Quark Gluon Plasma (QGP) evolution from the initial Heavy Ion collision to the final hadronic gas state by combining the Glauber model initial state conditions with eccentricity fluctuations, pre-equilibrium flow, UVH2+1 viscous hydrodynamics with lattice QCD Equation of State (EoS), a modified Cooper-Frye freeze-out and the UrQMD hadronic cascade. We then evaluate the model parameters using a comprehensive analytical framework which together with the described model we call CHIMERA. Within our framework, the initial state parameters, such as the initial temperature (Tinit), presence or absence of initial flow, viscosity over entropy density (η/S) and different Equations of State (EoS), are varied and then compared simultaneously to several experimental data observables: HBT radii, particle spectra and particle flow. χ2/nds values from comparison to the experimental data for each set of initial parameters will then used to find the optimal description of the QGP with parameters that are difficult to obtain experimentally, but are crucial to understanding of the matter produced.
NASA Astrophysics Data System (ADS)
Gunár, S.; Mackay, D. H.
2016-07-01
Aims: We analyze distributions of the magnetic field strength and prominence plasma (temperature, pressure, plasma β, and mass) using the 3D whole-prominence fine structure model. Methods: The model combines a 3D magnetic field configuration of an entire prominence, obtained from non-linear force-free field simulations, with a detailed semi-empirically derived description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Results: We show that in the modeled prominence, the variations of the magnetic field strength and its orientation are insignificant on scales comparable to the smallest dimensions of the observed prominence fine structures. We also show the ability of the 3D whole-prominence fine structure model to reveal the distribution of the prominence plasma with respect to its temperature within the prominence volume. This provides new insights into the composition of the prominence-corona transition region. We further demonstrate that the values of the plasma β are small throughout the majority of the modeled prominences when realistic photospheric magnetic flux distributions and prominence plasma parameters are assumed. While this is generally true, we also find that in the region with the deepest magnetic dips, the plasma β may increase towards unity. Finally, we show that the mass of the modeled prominence plasma is in good agreement with the mass of observed non-eruptive prominences.
NASA Astrophysics Data System (ADS)
Gavrilov, N. M.; Manuilova, R. O.
2016-12-01
We obtain average global distributions of the variances of the mesoscale variations in the atmospheric radio-refraction index (refractive index) at altitudes of 5-35 km from the data of the radio-occultation experiments performed during operation of the low-orbit GPS CHAMP satellite in the period 2001-2009. The filtering of the vertical profiles of the radio-refraction index allows one to determine the variances of the variations with vertical scales below 8 km. The latitudinal-temporal distributions of the zonal-mean variances of the index demonstrate significant interannual variations at various altitudes. Seasonal variations in the variances of radio refraction are studied. Quasi-biennial oscillations at low latitudes are revealed. Acoustic-gravity waves and turbulent and convective motions in the atmosphere can cause a spread of the radio-refraction index.
Bugaev, K. A.; Petrov, V. K.; Zinovjev, G. M.
2009-05-15
The influence of the medium-dependent finite width of quark gluon plasma (QGP) bags on their equation of state is analyzed within an exactly solvable model. It is argued that the large width of the QGP bags not only explains the observed deficit in the number of hadronic resonances but also clarifies the reason why the heavy QGP bags cannot be directly observed as metastable states in a hadronic phase. The model allows us to estimate the minimal value of the width of QGP bags being heavier than 2 GeV from a variety of the lattice QCD data and get that the minimal resonance width at zero temperature is about 600 MeV, whereas the minimal resonance width at the Hagedorn temperature is about 2000 MeV. As shown, these estimates are almost insensitive to the number of the elementary degrees of freedom. The recent lattice QCD data are analyzed and it is found that in addition to the {sigma}T{sup 4} term the lattice QCD pressure contains T-linear and T{sup 4}lnT terms in the range of temperatures between 240 and 420 MeV. The presence of the last term in the pressure bears almost no effect on the width estimates. Our analysis shows that at high temperatures the average mass and width of the QGP bags behave in accordance with the upper bound of the Regge trajectory asymptotics (the linear asymptotics), whereas at low temperatures they obey the lower bound of the Regge trajectory asymptotics (the square root one). Since the model explicitly contains the Hagedorn mass spectrum, it allows us to remove an existing contradiction between the finite number of hadronic Regge families and the Hagedorn idea of the exponentially growing mass spectrum of hadronic bags.
NASA Astrophysics Data System (ADS)
Benić, Sanjin; Fukushima, Kenji; Garcia-Montero, Oscar; Venugopalan, Raju
2017-01-01
We compute the cross section for photons emitted from sea quarks in proton-nucleus collisions at collider energies. The computation is performed within the dilute-dense kinematics of the Color Glass Condensate (CGC) effective field theory. Albeit the result obtained is formally at next-to-leading order in the CGC power counting, it provides the dominant contribution for central rapidities. We observe that the inclusive photon cross section is proportional to all-twist Wilson line correlators in the nucleus. These correlators also appear in quark-pair production; unlike the latter, photon production is insensitive to hadronization uncertainties and therefore more sensitive to multi-parton correlations in the gluon saturation regime of QCD. We demonstrate that k ⊥ and collinear factorized expressions for inclusive photon production are obtained as leading twist approximations to our result. In particular, the collinearly factorized expression is directly sensitive to the nuclear gluon distribution at small x. Other results of interest include the realization of the Low-Burnett-Kroll soft photon theorem in the CGC framework and a comparative study of how the photon amplitude is obtained in Lorenz and light-cone gauges.
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.
Quasilinear transport approach to equilibration of quark-gluon plasmas
Mrowczynski, Stanislaw; Mueller, Berndt
2010-03-15
We derive the transport equations of quark-gluon plasma in the quasilinear approximation. The equations are either of the Balescu-Lenard or Fokker-Planck form. The plasma's dynamics is assumed to be governed by longitudinal chromoelectric fields. The isotropic plasma, which is stable, and the two-stream system, which is unstable, are considered in detail. A process of equilibration is briefly discussed in both cases. The peaks of the two-stream distribution are shown to rapidly dissolve in time.
Quark gluon plasma: Overview and experimental results from E-735
Turkot, F.; Alexopoulos, T.; Allen, C.; Anderson, E.W.; Areti, H.; Banerjee, S.; Beery, P.D.; Biswas, N.N.; Bujak, A.; Carmony, D.D.
1988-12-14
A brief review of the phenomenology associated with the effort to produce and observe quark-gluon plasma in particle collisions is presented. E-735 has taken data during the 1987 Tevatron-Collider run at /square root/s = 1.8 TeV in pursuit of this goal. Results in the correlation of < p/sub t/ > with multiplicity for charged particles and p/sub t/ distributions for ..lambda../sup o/ and /bar Lambda//sup o/ are presented. 32 refs., 10 figs., 2 tabs.
Gluon Bremsstrahlung in Weakly-Coupled Plasmas
NASA Astrophysics Data System (ADS)
Arnold, Peter
2009-11-01
I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≳10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q̂.
Shear Viscosity in a Gluon Gas
Xu Zhe; Greiner, Carsten
2008-05-02
The relation of the shear viscosity coefficient to the recently introduced transport rate is derived within relativistic kinetic theory. We calculate the shear viscosity over entropy ratio {eta}/s for a gluon gas, which involves elastic gg{yields}gg perturbative QCD (PQCD) scatterings as well as inelastic gg{r_reversible}ggg PQCD bremsstrahlung. For {alpha}{sub s}=0.3 we find {eta}/s=0.13 and for {alpha}{sub s}=0.6, {eta}/s=0.076. The small {eta}/s values, which suggest strongly coupled systems, are due to the gluon bremsstrahlung incorporated.
Probing Quark-Gluon Interactions with Transverse Polarized Scattering
Slifer, K.; Rondon, O. A.; Crabb, D.; Day, D.; Frlez, E.; Lindgren, R.; McKee, P.; Norum, B.; Pocanic, D.; Prok, Y.; Sawatzky, B.; Smith, C.; Tajima, S.; Wang, K.; Zeier, M.; Zhu, H.; Aghalaryan, A.; Asaturyan, R.; Mkrtchyan, H.; Ahmidouch, A.
2010-09-03
We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d{sub 2}-tilde, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid. The fundamental Bjorken sum rule obtained from the a{sub 0} matrix element is satisfied at our low momentum transfer.
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.
Harvey, R.W.; Chan, V.S.
1996-12-31
Runaway of electrons to high energy during plasma disruptions occurs due to large induced toroidal electric fields which tend to maintain the toroidal plasma current, in accord with Lenz law. This has been observed in many tokamaks. Within the closed flux surfaces, the bounce-averaged CQL3D Fokker-Planck code is well suited to obtain the resulting electron distributions, nonthermal contributions to electrical conductivity, and runaway rates. The time-dependent 2D in momentum-space (p{sub {parallel}} and p{sub {perpendicular}}) distributions axe calculated on a radial array of noncircular flux surfaces, including bounce-averaging of the Fokker-Planck equation to account for toroidal trapping effects. In the steady state, the resulting distributions represent a balance between applied toroidal electric field, relativistic Coulomb collisions, and synchrotron radiation. The code can be run in a mode where the electrons are sourced at low velocity and run off the high velocity edge of the computational mesh, giving runaway rates at steady state. At small minor radius, the results closely match previous results reported by Kulsrud et al. It is found that the runaway rate has a strong dependence on inverse aspect ratio e, decreasing by a factor {approx} 5 as e increases from 0.0 to 0.3. The code can also be run with a radial diffusion and pinching term, simulating radial transport with plasma pinching to maintain a given density profile. Results show a transport reduction of runaways in the plasma center, and an enhancement towards the edge due to the electrons from the plasma center. Avalanching of runaways due to a knock-on electron source is being included.
NASA Technical Reports Server (NTRS)
Smiley, Robert F.; Haines, Gilbert A.
1949-01-01
Bureau of Aeronautics Design Specifications SS-IC-2 for water loads in sheltered water are compared with experimental water loads obtained during a full--scale landing investigation. This investigation was conducted with a JRS-1 flying boat which has a 20 degrees dead-rise V-bottom with a partial chine flare. The range of landing conditions included airspeeds between 88 and 126 feet per second, sinking speeds between 1.6 and 9.1 feet per second, flight angles less than 6 degrees, and trims between 2 degrees and 12 degrees. Landings were moderate and were made in calm water. Measurements were obtained of maximum over-all loads, maximum pitching moments, and pressure distributions. Maximum experimental loads include over-all load factors of 2g, moments of 128,000 pound-feet, and maximum local pressures greater than 40 pounds per square inch. Experimental over-all loads are approximately one-half the design values, while local pressures are of the same order as or larger than pressures calculated from specifications for plating, stringer, floor, and frame design. The value of this comparison is limited, to some extent, by the moderate conditions of the test and by the necessary simplifying assumptions used in comparing the specifications with the experimental loads.
Exploring Quarks, Gluons and the Higgs Boson
ERIC Educational Resources Information Center
Johansson, K. Erik
2013-01-01
With real particle collision data available on the web, the amazing dynamics of the fundamental particles of the standard model can be explored in classrooms. Complementing the events from the ATLAS experiment with animations of the fundamental processes on the quark and gluon level makes it possible to better understand the invisible world of…
Squeezed colour states in gluon jet
NASA Technical Reports Server (NTRS)
Kilin, S. YA.; Kuvshinov, V. I.; Firago, S. A.
1993-01-01
The possibility of the formation of squeezed states of gluon fields in quantum chromodynamics due to nonlinear nonperturbative self interaction during jet evolution in the process of e(+)e(-) annihilation into hadrons, which are analogous to the quantum photon squeezed states in quantum electrodynamics, is demonstrated. Additionally, the squeezing parameters are calculated.
Sambamurti Memorial Lecture: Spotlight on the Gluon
Michael Begelas
2016-07-12
Begel uses results from the Fermilab D0 and E706 experiments to explain how the production rate and energy spectrum of photons produced during proton collisions helped to clarify how the energy inside the proton is shared between quarks and gluons.
SU (2) Dirac-Yang-Mills quantum mechanics of spatially constant quark and gluon fields
NASA Astrophysics Data System (ADS)
Pavel, H.-P.
2011-06-01
The quantum mechanics of spatially constant SU (2) Yang-Mills- and Dirac-fields minimally coupled to each other is investigated as the strong coupling limit of 2-color-QCD. Using a canonical transformation of the quark and gluon fields, which Abelianises the Gauss law constraints to be implemented, the corresponding unconstrained Hamiltonian and total angular momentum are derived. In the same way as this reduces the colored spin-1 gluons to unconstrained colorless spin-0 and spin-2 gluons, it reduces the colored spin-1/2 quarks to unconstrained colorless spin-0 and spin-1 quarks. These however continue to satisfy anti-commutation relations and hence the Pauli-exclusion principle. The obtained unconstrained Hamiltonian is then rewritten into a form, which separates the rotational from the scalar degrees of freedom. In this form the low-energy spectrum can be obtained with high accuracy. As an illustrative example, the spin-0 energy-spectrum of the quark-gluon system is calculated for massless quarks of one flavor. It is found, that only for the case of 4 reduced quarks (half-filling) satisfying the boundary condition of particle-antiparticle C-symmetry, states with energy lower than for the pure-gluon case are obtained. These are the ground state, with an energy about 20% lower than for the pure-gluon case and the formation of a quark condensate, and the sigma-antisigma excitation with an energy about a fifth of that of the first glueball excitation.
NASA Technical Reports Server (NTRS)
Peters, B. C., Jr.; Walker, H. F.
1976-01-01
The problem of obtaining numerically maximum likelihood estimates of the parameters for a mixture of normal distributions is addressed. In recent literature, a certain successive approximations procedure, based on the likelihood equations, is shown empirically to be effective in numerically approximating such maximum-likelihood estimates; however, the reliability of this procedure was not established theoretically. Here, a general iterative procedure is introduced, of the generalized steepest-ascent (deflected-gradient) type, which is just the procedure known in the literature when the step-size is taken to be 1. With probability 1 as the sample size grows large, it is shown that this procedure converges locally to the strongly consistent maximum-likelihood estimate whenever the step-size lies between 0 and 2. The step-size which yields optimal local convergence rates for large samples is determined in a sense by the separation of the component normal densities and is bounded below by a number between 1 and 2.
QCD equations of state and the quark-gluon plasma liquid model
NASA Astrophysics Data System (ADS)
Letessier, Jean; Rafelski, Johann
2003-03-01
Recent advances in the study of equations of state of thermal lattice quantum chromodynamics obtained at nonzero baryon density allow validation of the quark-gluon plasma (QGP) liquid model equations of state (EOS). We study here the properties of the QGP-EOS near to the phase transformation boundary at finite baryon density and show a close agreement with the lattice results.
Gluon saturation and Feynman scaling in leading neutron production
NASA Astrophysics Data System (ADS)
Carvalho, F.; Gonçalves, V. P.; Spiering, D.; Navarra, F. S.
2016-01-01
In this paper we extend the color dipole formalism for the study of leading neutron production in e + p → e + n + X collisions at high energies and estimate the related observables which were measured at HERA and could be analyzed in future electron-proton (ep) colliders. In particular, we calculate the Feynman xF distribution of leading neutrons, which is expressed in terms of the pion flux and the photon-pion total cross section. In the color dipole formalism, the photon-pion cross section is described in terms of the dipole-pion scattering amplitude, which contains information about the QCD dynamics at high energies and gluon saturation effects. We consider different models for the scattering amplitude, which have been used to describe the inclusive and diffractive ep HERA data. Moreover, the model dependence of our predictions with the description of the pion flux is analyzed in detail. We demonstrate the recently released H1 leading neutron spectra can be described using the color dipole formalism and that these spectra could help us to observe more clearly gluon saturation effects in future ep colliders.
NASA Astrophysics Data System (ADS)
Zeng, X.; Lancelle, C.; Thurber, C. H.; Fratta, D.; Wang, H. F.; Chalari, A.; Clarke, A.
2015-12-01
The field test of Distributed Acoustic Sensing (DAS) conducted at Garner Valley, California on September 11-12, 2013 provided a continuous overnight record of ambient noise. The DAS array recorded ground motions every one meter of optical cable that was arranged approximately in the shape of a rectangle with dimensions of 160 m by 80 m. The long dimension of the array was adjacent to a state highway. Three hours of record were used to compute noise cross-correlation functions (NCFs) in one-minute windows. The trace from each sensor channel was pre-processed by downsampling to 200 Hz, followed by normalization in the time-domain and bandpass filtering between 2 and 20 Hz (Bensen et al., 2007). The one-minute NCFs were then stacked using the time-frequency domain phase-weighted stacking method (Schimmel & Gallart, 2007). The NCFs between channels were asymmetrical reflecting the direction of traffic noise. The group velocities were found using the frequency-time analysis method. The energy was concentrated between 5 and 15 Hz, which falls into the typical traffic noise frequency band. The resulting velocities were between 100 and 300 m/s for frequencies between 10 and 20 Hz, which are in the same range as described in the results for surface-wave dispersion obtained using an active source for the same site (Lancelle et al., 2015). The group velocity starts to decrease for frequencies greater than ~10 Hz, which was expected on the basis of a previous shear-wave velocity model (Steidl et al., 1996). Then, the phase velocity was calculated using the multichannel analysis of surface wave technique (MASW - Park et al., 1999) with 114 NCFs spaced one meter apart. The resulting dispersion curve between 5 and 15 Hz gave phase velocities that ranged from approximately 170 m/s at 15 Hz to 250 m/s at 5 Hz. These results are consistent with other results of active-source DAS and seismometer records obtained at the Garner Valley site (e.g., Stokoe et al. 2004). This analysis is
Gluon-glueball duality and glueball searches
Nussinov, Shmuel; Shrock, Robert
2009-09-01
We discuss a notion of gluon-glueball duality analogous to quark-hadron duality. We apply this idea to the radiative decay of heavy orthoquarkonium, QQ{yields}{gamma}gg, which has been used to search for glueballs. The duality is first introduced in two simplified contexts: (i) a hypothetical version of QCD without any light quarks and (ii) QCD in the large-N{sub c} limit. We then discuss how an approximate form of this duality could hold in real QCD, based on a hierarchy of time scales in the temporal evolution of the gg subsystem in radiative orthoquarkonium decay. We apply this notion of gluon-glueball duality to suggest a method that could be useful in experimental searches for glueballs.
We compare measurements of aerosol mass concentrations obtained gravimetrically using Teflon coated glass fiber filters and by integrating mass distributions measured with the differential mobility analyzer–aerosol particle mass analyzer (DMA–APM) technique (Aero...
Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso; Koseki, Shigenobu
2016-12-01
We investigated a bacterial sample preparation procedure for single-cell studies. In the present study, we examined whether single bacterial cells obtained via 10-fold dilution followed a theoretical Poisson distribution. Four serotypes of Salmonella enterica, three serotypes of enterohaemorrhagic Escherichia coli and one serotype of Listeria monocytogenes were used as sample bacteria. An inoculum of each serotype was prepared via a 10-fold dilution series to obtain bacterial cell counts with mean values of one or two. To determine whether the experimentally obtained bacterial cell counts follow a theoretical Poisson distribution, a likelihood ratio test between the experimentally obtained cell counts and Poisson distribution which parameter estimated by maximum likelihood estimation (MLE) was conducted. The bacterial cell counts of each serotype sufficiently followed a Poisson distribution. Furthermore, to examine the validity of the parameters of Poisson distribution from experimentally obtained bacterial cell counts, we compared these with the parameters of a Poisson distribution that were estimated using random number generation via computer simulation. The Poisson distribution parameters experimentally obtained from bacterial cell counts were within the range of the parameters estimated using a computer simulation. These results demonstrate that the bacterial cell counts of each serotype obtained via 10-fold dilution followed a Poisson distribution. The fact that the frequency of bacterial cell counts follows a Poisson distribution at low number would be applied to some single-cell studies with a few bacterial cells. In particular, the procedure presented in this study enables us to develop an inactivation model at the single-cell level that can estimate the variability of survival bacterial numbers during the bacterial death process.
We report the draft genome sequences of six Mycobacterium immunogenum isolated from a chloraminated drinking water distribution system simulator subjected to changes in operational parameters. M. immunogenum, a rapidly growing mycobacteria previously reported as the cause of hyp...
Revetta, Randy P.
2016-01-01
We report here the draft genome sequences of six Mycobacterium immunogenum strains isolated from a chloraminated drinking water distribution system simulator subjected to changes in operational parameters. M. immunogenum, a rapidly growing mycobacterium previously reported to be the cause of hypersensitivity pneumonitis from contaminated metalworking fluid aerosols, is becoming a public health concern. PMID:26744376
Code of Federal Regulations, 2013 CFR
2013-07-01
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Code of Federal Regulations, 2012 CFR
2012-07-01
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Code of Federal Regulations, 2011 CFR
2011-07-01
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Code of Federal Regulations, 2014 CFR
2014-07-01
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2010-07-01
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Technology Transfer Automated Retrieval System (TEKTRAN)
In fiber length measurement by the rapid method of testing fiber beards instead of testing individual fibers, only the fiber portion projected from the fiber clamp can be measured. The length distribution of the projecting portion is very different from that of the original sample. The Part 1 pape...
Production of J /ψ +χc and J /ψ +J /ψ with real gluon emission at the LHC
NASA Astrophysics Data System (ADS)
Likhoded, A. K.; Luchinsky, A. V.; Poslavsky, S. V.
2016-09-01
In the present work we study production of J /ψ +χc and J /ψ +J /ψ at the LHC. The first process is forbidden at the leading order in gluon fusion due to the C -parity conservation, and the first nonvanishing contribution is given by the process with the additional emission of a real gluon. Considering the direct production of J /ψ +J /ψ , where the leading order is allowed, we have found that the contribution from the higher order process with real gluon emission is comparable and even more significant than the leading order. Moreover, account of this higher order effect dramatically changes kinematical distributions. Through the present paper we study in detail different channels of paired J /ψ +J /ψ production: direct J /ψ +J /ψ production, feed-down from the J /ψ +χc channel, and double parton scattering. We also try to find kinematical distributions that are most suitable to separate these different channels.
Evolution to the quark–gluon plasma
NASA Astrophysics Data System (ADS)
Fukushima, Kenji
2017-02-01
Theoretical studies on the early-time dynamics in the ultra-relativistic heavy-ion collisions are reviewed, including pedagogical introductions on the initial condition with small-\\text{x} gluons treated as a color glass condensate, the bottom–up thermalization scenario, plasma/glasma instabilities, basics of some formulations such as the kinetic equations and the classical statistical simulation. More detailed discussions follow to make an overview of recent developments on the fast isotropization, the onset of hydrodynamics, and the transient behavior of momentum spectral cascades.
Evolution to the quark-gluon plasma.
Fukushima, Kenji
2017-02-01
Theoretical studies on the early-time dynamics in the ultra-relativistic heavy-ion collisions are reviewed, including pedagogical introductions on the initial condition with small-[Formula: see text] gluons treated as a color glass condensate, the bottom-up thermalization scenario, plasma/glasma instabilities, basics of some formulations such as the kinetic equations and the classical statistical simulation. More detailed discussions follow to make an overview of recent developments on the fast isotropization, the onset of hydrodynamics, and the transient behavior of momentum spectral cascades.
Coulomb-gauge ghost and gluon propagators in SU(3) lattice Yang-Mills theory
NASA Astrophysics Data System (ADS)
Nakagawa, Y.; Voigt, A.; Ilgenfritz, E.-M.; Müller-Preussker, M.; Nakamura, A.; Saito, T.; Sternbeck, A.; Toki, H.
2009-06-01
We study the momentum dependence of the ghost propagator and of the space and time components of the gluon propagator at equal time in pure SU(3) lattice Coulomb-gauge theory carrying out a joint analysis of data collected independently at the Research Center for Nuclear Physics, Osaka and Humboldt University, Berlin. We focus on the scaling behavior of these propagators at β=5.8,…,6.2 and apply a matching technique to relate the data for the different lattice cutoffs. Thereby, lattice artifacts are found to be rather strong for both instantaneous gluon propagators at a large momentum. As a byproduct we obtain the respective lattice scale dependences a(β) for the transversal gluon and the ghost propagator which indeed run faster with β than two-loop running, but slightly slower than what is known from the Necco-Sommer analysis of the heavy quark potential. The abnormal a(β) dependence as determined from the instantaneous time-time gluon propagator, D44, remains a problem, though. The role of residual gauge-fixing influencing D44 is discussed.
Renormalization group analysis of the gluon mass equation
NASA Astrophysics Data System (ADS)
Aguilar, A. C.; Binosi, D.; Papavassiliou, J.
2014-04-01
We carry out a systematic study of the renormalization properties of the integral equation that determines the momentum evolution of the effective gluon mass in pure Yang-Mills theory, without quark effects taken into account. A detailed, all-order analysis of the complete kernel appearing in this particular equation, derived in the Landau gauge, reveals that the renormalization procedure may be accomplished through the sole use of ingredients known from the standard perturbative treatment of the theory, with no additional assumptions. However, the subtle interplay of terms operating at the level of the exact equation gets distorted by the approximations usually employed when evaluating the aforementioned kernel. This fact is reflected in the form of the obtained solutions, for which the deviations from the correct behavior are best quantified by resorting to appropriately defined renormalization-group invariant quantities. This analysis, in turn, provides a solid guiding principle for improving the form of the kernel, and furnishes a well-defined criterion for discriminating between various possibilities. Certain renormalization-group inspired Ansätze for the kernel are then proposed, and their numerical implications are explored in detail. One of the solutions obtained fulfills the theoretical expectations to a high degree of accuracy, yielding a gluon mass that is positive definite throughout the entire range of physical momenta, and displays in the ultraviolet the so-called "power-law" running, in agreement with standard arguments based on the operator product expansion. Some of the technical difficulties thwarting a more rigorous determination of the kernel are discussed, and possible future directions are briefly mentioned.
NASA Astrophysics Data System (ADS)
Aaltonen, T.; Adelman, J.; Akimoto, T.; Albrow, M. G.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Azzurri, P.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Bartsch, V.; Bauer, G.; Beauchemin, P.-H.; Bedeschi, F.; Bednar, P.; Beecher, D.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Beringer, J.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bolla, G.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.; Choudalakis, G.; Chuang, S. H.; Chung, K.; Chung, W. H.; Chung, Y. S.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.; Conway, J.; Copic, K.; Cordelli, M.; Cortiana, G.; Cox, D. J.; Crescioli, F.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.; Dagenhart, D.; Datta, M.; Davies, T.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca, C.; Demortier, L.; Deng, J.; Deninno, M.; Derwent, P. F.; di Giovanni, G. P.; Dionisi, C.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Donini, J.; Dorigo, T.; Dube, S.; Efron, J.; Elagin, A.; Erbacher, R.; Errede, D.; Errede, S.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Genser, K.; Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; Guimaraes da Costa, J.; Gunay-Unalan, Z.; Haber, C.; Hahn, K.; Hahn, S. R.; Halkiadakis, E.; Han, B.-Y.; Han, J. Y.; Handler, R.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harper, S.; Harr, R. F.; Harris, R. M.; Hartz, M.; Hatakeyama, K.; Hauser, J.; Hays, C.; Heck, M.; Heijboer, A.; Heinemann, B.; Heinrich, J.; Henderson, C.; Herndon, M.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Huffman, B. T.; Hughes, R. E.; Husemann, U.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jayatilaka, B.; Jeon, E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin, P. E.; Kato, Y.; Kephart, R.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Knuteson, B.; Ko, B. R.; Koay, S. A.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kubo, T.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.; Kusakabe, Y.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, E.; Lee, S. W.; Leone, S.; Lewis, J. D.; Lin, C. S.; Linacre, J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.; Loginov, A.; Loreti, M.; Lovas, L.; Lu, R.-S.; Lucchesi, D.; Lueck, J.; Luci, C.; Lujan, P.; Lukens, P.; Lungu, G.; Lyons, L.; Lys, J.; Lysak, R.; Lytken, E.; Mack, P.; MacQueen, D.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maki, T.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Maruyama, T.; Mastrandrea, P.; Masubuchi, T.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione, A.; Merkel, P.; Mesropian, C.; Miao, T.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlok, J.; Movilla Fernandez, P.; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Mumford, R.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Nagano, A.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Necula, V.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Osterberg, K.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramonov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Poukhov, O.; Pounder, N.; Prakoshyn, F.; Pronko, A.; Proudfoot, J.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Reisert, B.; Rekovic, V.; Renton, P.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ, J.; Rusu, V.; Saarikko, H.; Safonov, A.; Sakumoto, W. K.; Saltó, O.; Santi, L.; Sarkar, S.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Scheidle, T.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scott, A. L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sfyrla, A.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Sherman, D.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon, Y.; Shreyber, I.; Sidoti, A.; Sinervo, P.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur, R.; Soha, A.; Somalwar, S.; Sorin, V.; Spalding, J.; Spreitzer, T.; Squillacioti, P.; Stanitzki, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Stuart, D.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Suzuki, T.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tecchio, M.; Teng, P. K.; Terashi, K.; Thom, J.; Thompson, A. S.; Thompson, G. A.; Thomson, E.; Tipton, P.; Tiwari, V.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Tourneur, S.; Tu, Y.; Turini, N.; Ukegawa, F.; Vallecorsa, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Veszpremi, V.; Vidal, M.; Vidal, R.; Vila, I.; Vilar, R.; Vine, T.; Vogel, M.; Volobouev, I.; Volpi, G.; Würthwein, F.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner-Kuhr, J.; Wagner, W.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Williams, G.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wright, T.; Wu, X.; Wynne, S. M.; Xie, S.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanello, L.; Zanetti, A.; Zaw, I.; Zhang, X.; Zheng, Y.; Zucchelli, S.
2009-02-01
We present a measurement of the ratio of the t tmacr production cross section via gluon-gluon fusion to the total t tmacr production cross section in p pmacr collisions at s=1.96TeV at the Tevatron. Using a data sample with an integrated luminosity of 955pb-1 recorded by the CDF II detector at Fermilab, we select events based on the t tmacr decay to lepton+jets. Using an artificial neural network technique we discriminate between t tmacr events produced via q qmacr annihilation and gg fusion, and find Gf=σ(gg→t tmacr )/σ(p pmacr →t tmacr )<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most stringent measurement of this quantity by CDF to date, Gf=0.07-0.07+0.15.
NASA Astrophysics Data System (ADS)
Audenaert, Jan; Leloup, Frédéric B.; Van Giel, Bart; Durinck, Guy; Deconinck, Geert; Hanselaer, Peter
2013-09-01
The reliability of ray tracing simulations is strongly dependent on the accuracy of the input data such as the bidirectional reflectance distribution function (BRDF). Software developers offer the possibility to implement BRDF data in different ways, ranging from simple predefined functions to detailed tabulated data. The impact of the accuracy of the implemented reflectance model on ray tracing simulations has been investigated. A light-emitting diode device including a frequently employed diffuse reflector [microcellular polyethylene terephthalate (MCPET)] was constructed. The luminous intensity distribution (LID) and luminance distribution from a specific viewpoint were measured with a near-field goniophotometer. Both distributions were also simulated by use of ray tracing software. Three different reflection models of MCPET were introduced, varying in complexity: a diffuse model, a diffuse/specular model, and a model containing tabulated BRDF data. A good agreement between the measured and simulated LID was found irrespective of the applied model. However, the luminance distributions only corresponded when the most accurate BRDF model was applied. This proves that even for diffuse reflective materials, a simple BRDF model may only be employed for simulations of the LID; for evaluation of luminance distributions, more complex models are needed.
Wakes in the quark-gluon plasma
Chakraborty, Purnendu; Mustafa, Munshi G.; Thoma, Markus H.
2006-11-01
Using the high temperature approximation we study, within the linear response theory, the wake in the quark-gluon plasma by a fast parton owing to dynamical screening in the spacelike region. When the parton moves with a speed less than the average speed of the plasmon, we find that the wake structure corresponds to a screening charge cloud traveling with the parton with one sign flip in the induced charge density resulting in a Lennard-Jones type potential in the outward flow with a short range repulsive and a long range attractive part. On the other hand if the parton moves with a speed higher than that of plasmon, the wake structure in the induced charge density is found to have alternate sign flips and the wake potential in the outward flow oscillates analogous to Cerenkov-like wave generation with a Mach cone structure trailing the moving parton. The potential normal to the motion of the parton indicates a transverse flow in the system. We also calculate the potential due to a color dipole and discuss consequences of possible new bound states and J/{psi} suppression in the quark-gluon plasma.
Gluon Fragmentation Functions in the Nambu-Jona-Lasinio Model
NASA Astrophysics Data System (ADS)
Yang, Dong-Jing; Li, Hsiang-nan
We derive gluon fragmentation functions in the Nambu-Jona-Lasinio (NJL) model by approximating a gluon as a fictitious color-octet quark-anti-quark (qbar{q}) pair. Gluon elementary fragmentation functions are derived from the quark and anti-quark elementary fragmentation functions for emitting specific mesons in the NJL model under the requirement that the qbar{q} pair maintains in the flavor-singlet state after meson emission. An iteration method and an inverse matrix method based on the gluon elementary fragmentation functions then yield the gluon fragmentation functions at the model scale. It is found that the resultant gluon fragmentation functions are stable with respect to variation of relevant model parameters, especially after QCD evolution to a higher scale is implemented. We show that the inclusion of the gluon fragmentation functions into the theoretical predictions from only the quark fragmentation functions greatly improve the agreement with the SLD data for the pion and kaon productions in e+e- annihilation. Our proposal provides a plausible construct for the gluon fragmentation functions, which are supposed to be null in the NJL model.
NASA Technical Reports Server (NTRS)
Naumann, R. J.; Clifton, K. S.
1973-01-01
Low light level television systems offer the ability to observe meteors as faint as 10th magnitude which allows the extension of optical meteor data to masses as small as 0.0001 gram. The results of these observations, using image orthicons and intensified vidicons, are presented along with an interpretation in terms of mass flux. This interpretation includes the development of a relationship between peak luminosity of a meteor and mass, velocity, and zenith angle that was derived from single body meteor theory and compares favorably with results obtained from the artificial meteor program. Also included in the mass flux interpretation is an analysis of the observation response of a LLLTV system to fixed and moving point sources.
NASA Astrophysics Data System (ADS)
Canon-Tapia, E.
2014-12-01
The distribution of volcanic features is ultimately controlled by processes taking place beneath the surface of a planet. For this reason, characterization of volcano distribution at a global scale can be used to obtain insights concerning dynamic aspects of planetary interiors. In this work, description of the distribution of volcanic features observed on Earth and Venus is completed using density contours obtained with the Fisher kernel. Attention is focused on similar features observed in both planets. In particular two features are examined with more detail: First, a pattern of groups of clusters defining the boundaries of elliptical regions that tentatively can be associated to large mantle plumes. Second, the existence of a uniform distribution of background volcanism. The former pattern is considered to constitute the first order convective pattern of the mantle in Venus, and although it is present on Earth, it is not as prominent. In contrast, the persistent occurrence of volcanic clusters at a lower significance level, suggests the occurrence of a different scale of mantle convection that controls a more uniformly distributed volcanism. Both, the first order related to large mantle-plumes and the background volcanism are superimposed on Earth to the volcanism controlled by plate tectonics. Consequently, the global distribution of volcanism in both planets reveals that at least three types of mantle convection can take place in the terrestrial planets, and that such types of mantle convection can coexist simultaneously in one given planet, although in each case, a dominant mode is different.
Probing Quark-Gluon Structure of Matter with e-p and e-A Reactions
Jian-Ping Chen
2011-11-01
Understanding the strong interaction (QCD) in the truly strong ('non-perturbative') region remains a major challenge in modern physics. Nucleon and nuclei provide natural laboratories to study the strong interaction. The quark-gluon structure of the nucleon and nuclei are important by themselves since they are the main (>99%) part of the visible world. With electroweak interaction well-understood, e-p and e-A are clean means to probe the nucleon and nuclear structure and to study the strong interaction (QCD). Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinally-polarized parton (quark and gluon) distributions (PDFs). It has becoming clear that transverse spin and transverse structure (both transverse spatial structure via generalized parton distributions (GPDs) and transverse momentum structure via transverse- momentum-dependent distributions (TMDs)) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction(QCD). The transverse spin, GPDs and TMDs have been the subjects of increasingly intense theoretical and experimental study recently. With 12 GeV energy upgrade, Jefferson Lab (JLab) will provide the most precise multi-dimensional map of the TMDs and GPDs in the valence quark region through Semi-Inclusive DIS (SIDIS) and Deep-Exclusive experiments, providing a 3-d partonic picture of the nucleon in momentum and spatial spaces. The precision information on TMDs and GPDs will provide access to the quark orbital angular momentum and its correlation with the quark and the nucleon spins. The planned future Electron-Ion Collider (EIC) will enable a precision study of the TMDs and GPDs of the sea quarks and gluons, in addition to completing the study in the valence region. The EIC will also open a new window to study the role of gluons in nuclei.
From gluon topology to chiral anomaly: Emergent phenomena in quark-gluon plasma
NASA Astrophysics Data System (ADS)
Liao, Jinfeng
2017-01-01
Heavy-ion collision experiments at RHIC and the LHC have found a new emergent phase of QCD, a strongly coupled quark-gluon plasma (sQGP) that is distinctively different from either the low temperature hadron phase or the very high temperature weakly coupled plasma phase. Highly nontrivial emergent phenomena occur in such sQGP and two examples will be discussed in this contribution: the magnetic component of sQGP that stems from topologically nontrivial configurations in the gluon sector; and the anomalous chiral transport that arises as macroscopic manifestation of microscopic chiral anomaly in the quark sector. For both examples, their important roles in explaining pertinent heavy-ion data will be emphasized.
Gluon-ghost condensate of mass dimension 2 in the Curci-Ferrari gauge
NASA Astrophysics Data System (ADS)
Dudal, D.; Verschelde, H.; Lemes, V. E. R.; Sarandy, M. S.; Sorella, S. P.; Picariello, M.
2003-11-01
The effective potential for an on-shell BRST invariant gluon-ghost condensate of mass dimension 2 in the Curci-Ferrari gauge in SU( N) Yang-Mills is analysed by combining the local composite operator technique with the algebraic renormalization. We pay attention to the gauge parameter independence of the vacuum energy obtained in the considered framework and discuss the Landau gauge as an interesting special case.
The gluon contribution to nucleon spin
Antje Bruell
2006-04-06
EIC is the ideal machine to finally determine the contribution of the gluons to the nucleon spin. Measurements of G{sub 1} will allow: (1) a determination of {Delta}G/G from its scaling violation and (2) a statistically very precise determination of the Bjorken Sum (systematics due to uncertainty in proton beam polarization). Measurements of charm cross section asymmetries will provide a precise determination of {Delta}G/G for 0.003 < x < 0.5 at a fixed value of Q{sup 2} of {approx} GeV{sup 2} provided they can measure the scattered electron at extremely small angles; separate the primary and secondary vertex with sufficient precision; and control the contribution of resolved photons. More work is needed to define the necessary detector requirements.
Anomalous gluon content of the proton
NASA Astrophysics Data System (ADS)
Hatsuda, T.
1990-01-01
The proton matrix element of the flavor singlet axial current is evaluated using the large Nc chiral dynamics satisfying the anomalous Ward-Takahashi identities. We relate the quark and gluon contributions ( Δq and Δg) of the matrix element to the nucleon-meson ( η, η', π0) pseudo-scalar coupling constants. It is shown that the weak η'-nucleon coupling is preferred to reproduce the recent EMC data. The origin of the anomalous value of Δg pointed out by Cheng and Li is clarified in the context of the large isospin violation due to the anomaly. A subtlety related to the matrix element of the gauge-variant topological current Kμ is also discussed.
Check of the gluon-reggeization condition in the next-to-leading order: Gluon part
Kozlov, M. G. Reznichenko, A. V. Fadin, V. S.
2012-04-15
The last bootstrap condition whose validity has not been verified to date is considered. This condition is an indispensable element in the unitarity-relation-based proof of themulti-Regge form of highenergy gluon-exchange QCD amplitudes in the next-to-leading-logarithm approximation. The approach used here relies on the s-channel unitarity and makes it possible to reproduce successively, in all orders of perturbation theory, themulti-Regge form of the amplitude, provided that specific nonlinear relations, called bootstrap conditions, hold. All of them were derived, and all, with the exception of one, were tested. An explicit verification of fulfillment of the last condition (the bootstrap condition for the inelastic amplitude of the production of one gluon inmulti-Regge kinematics) is performed. In our preceding study, we performed such a verification for purely fermion contributions, while, in the present study, we complete it for one-loop gluon corrections to the components of the condition being considered.
Quark-gluon discrimination in the search for gluino pair production at the LHC
Bhattacherjee, Biplob; Mukhopadhyay, Satyanarayan; Nojiri, Mihoko M.; ...
2017-01-11
Here, we study the impact of including quark- and gluon-initiated jet discrimination in the search for strongly interacting supersymmetric particles at the LHC. Taking the example of gluino pair production, considerable improvement is observed in the LHC search reach on including the jet substructure observables to the standard kinematic variables within a multivariate analysis. In particular, quark and gluon jet separation has higher impact in the region of intermediate mass-gap between the gluino and the lightest neutralino, as the difference between the signal and the standard model background kinematic distributions is reduced in this region. We also compare the predictionsmore » from different Monte Carlo event generators to estimate the uncertainty originating from the modelling of the parton shower and hadronization processes.« less
Quark-gluon discrimination in the search for gluino pair production at the LHC
NASA Astrophysics Data System (ADS)
Bhattacherjee, Biplob; Mukhopadhyay, Satyanarayan; Nojiri, Mihoko M.; Sakaki, Yasuhito; Webber, Bryan R.
2017-01-01
We study the impact of including quark- and gluon-initiated jet discrimination in the search for strongly interacting supersymmetric particles at the LHC. Taking the example of gluino pair production, considerable improvement is observed in the LHC search reach on including the jet substructure observables to the standard kinematic variables within a multivariate analysis. In particular, quark and gluon jet separation has higher impact in the region of intermediate mass-gap between the gluino and the lightest neutralino, as the difference between the signal and the standard model background kinematic distributions is reduced in this region. We also compare the predictions from different Monte Carlo event generators to estimate the uncertainty originating from the modelling of the parton shower and hadronization processes.
Inclusive b-jet and bb¯-dijet production at the LHC via Reggeized gluons
NASA Astrophysics Data System (ADS)
Saleev, V. A.; Shipilova, A. V.
2012-08-01
We study inclusive b-jet and bb¯-dijet production at the CERN LHC invoking the hypothesis of gluon Reggeization in t-channel exchanges at high energy. The b-jet cross section includes contributions from open b-quark production and from b-quark production via gluon-to-bottom-pair fragmentation. The transverse-momentum distributions of inclusive b-jet production measured with the ATLAS detector at the CERN LHC in different rapidity ranges are calculated both within multi-Regge kinematics and quasi-multi-Regge kinematics. The bb¯-dijet cross section is calculated within quasi-multi-Regge kinematics as a function of the dijet invariant mass Mjj, the azimuthal angle between the two jets Δϕ, and the angular variable χ. At the numerical calculation, we adopt the Kimber-Martin-Ryskin and Blümlein prescriptions to derive unintegrated gluon distribution function of the proton from its collinear counterpart for which we use the Martin-Roberts-Stirling-Thorne set. We find good agreement with measurements by the ATLAS and CMS Collaborations at the LHC at the hadronic c.m. energy of S=7TeV.
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Ivanov, Yu. B.; Fortov, V. E.; Bonitz, M.; Levashov, P. R.
2013-03-01
Based on the quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for the calculation of thermodynamic properties and—closely related to the latter—a Wigner dynamics method for calculation of transport properties of the QGP are formulated. The QGP partition function is presented in the form of a color path integral with a new relativistic measure instead of the Gaussian one traditionally used in the Feynman-Wiener path integral. A procedure of sampling color variables according to the SU(3) group Haar measure is developed for integration over the color variable. It is shown that the PIMC method is able to reproduce the lattice QCD equation of state at zero baryon chemical potential at realistic model parameters (i.e., quasiparticle masses and coupling constant) and also yields valuable insight into the internal structure of the QGP. Our results indicate that the QGP reveals quantum liquidlike(rather than gaslike) properties up to the highest considered temperature of 525 MeV. The pair distribution functions clearly reflect the existence of gluon-gluon bound states, i.e., glueballs, at temperatures just above the phase transition, while mesonlike qq¯ bound states are not found. The calculated self-diffusion coefficient agrees well with some estimates of the heavy-quark diffusion constant available from recent lattice data and also with an analysis of heavy-quark quenching in experiments on ultrarelativistic heavy-ion collisions, however, appreciably exceeds other estimates. The lattice and heavy-quark-quenching results on the heavy-quark diffusion are still rather diverse. The obtained results for the shear viscosity are in the range of those deduced from an analysis of the experimental elliptic flow in ultrarelativistic heavy-ions collisions, i.e., in terms the viscosity-to-entropy ratio, 1/4π≲η/S<2.5/4π, in the temperature range from 170 to 440 MeV.
NASA Astrophysics Data System (ADS)
Cañon-Tapia, Edgardo
2014-06-01
The distribution of volcanic features is ultimately controlled by processes taking place beneath the surface of a planet. For this reason, characterization of volcano distribution at a global scale can be used to obtain insights concerning dynamic aspects of planetary interiors. Until present, studies of this type commonly have focused on volcanic features of a specific type (e.g., large volcanoes in Venus or hot-spot volcanism on Earth), or have concentrated on relatively small regions (i.e., vent distribution within individual volcanic fields), but no comparison of extensive databases has been made by using the same tools in both planets. In this work, the description of the distribution of volcanic features observed over the entire surface of Venus is made using the same tool used for Earth, and is applied to an extensive database. The analysis is based on density contours obtained with the Fisher kernel. As a result, several groupings of volcanoes are identified refining the already documented concentration of volcanoes on the BAT zone. In particular some doughnut-like patterns are observed that might be related to the action of mantle plumes. The occurrence of such features on Earth, as well as the existence of a uniform distribution of background volcanism on both planets, suggests similarities on their geodynamic behavior that had not been identified previously.
Verbaro, Daniel; Ghosh, Indrajit; Nau, Werner M; Schweitzer-Stenner, Reinhard
2010-12-30
Structural preferences in the unfolded state of peptides determined by molecular dynamics still contradict experimental data. A remedy in this regard has been suggested by MD simulations with an optimized Amber force field ff03* ( Best, R. Hummer, G. J. Phys. Chem. B 2009 , 113 , 9004 - 9015 ). The simulations yielded a statistical coil distribution for alanine which is at variance with recent experimental results. To check the validity of this distribution, we investigated the peptide H-A(5)W-OH, which with the exception of the additional terminal tryptophan is analogous to the peptide used to optimize the force fields ff03*. Electronic circular dichroism, vibrational circular dichroism, and infrared spectroscopy as well as J-coupling constants obtained from NMR experiments were used to derive the peptide's conformational ensemble. Additionally, Förster resonance energy transfer between the terminal chromophores of the fluorescently labeled peptide analogue H-Dbo-A(5)W-OH was used to determine its average length, from which the end-to-end distance of the unlabeled peptide was estimated. Qualitatively, the experimental (3)J(H(N),C(α)), VCD, and ECD indicated a preference of alanine for polyproline II-like conformations. The experimental (3)J(H(N),C(α)) for A(5)W closely resembles the constants obtained for A(5). In order to quantitatively relate the conformational distribution of A(5) obtained with the optimized AMBER ff03* force field to experimental data, the former was used to derive a distribution function which expressed the conformational ensemble as a mixture of polyproline II, β-strand, helical, and turn conformations. This model was found to satisfactorily reproduce all experimental J-coupling constants. We employed the model to calculate the amide I' profiles of the IR and vibrational circular dichroism spectrum of A(5)W, as well as the distance between the two terminal peptide carbonyls. This led to an underestimated negative VCD couplet and an
One-loop amplitudes of gluons in supersymmetric QCD
Britto, Ruth; Buchbinder, Evgeny; Cachazo, Freddy; Feng Bo
2005-09-15
One-loop amplitudes of gluons in supersymmetric Yang-Mills are four-dimensional cut-constructible. This means that they can be determined from their unitarity cuts. We present a new systematic procedure to explicitly carry out any finite unitarity cut integral. The procedure naturally separates the contributions from bubble, triangle and box scalar integrals. This technique allows the systematic calculation of N=1 amplitudes of gluons. As an application we compute all next-to-MHV six-gluon amplitudes in N=1 super-Yang-Mills.
Quark-gluon vertex model and lattice-QCD data
Bhagwat, M.S.; Tandy, P.C.
2004-11-01
A model for the dressed-quark-gluon vertex, at zero gluon momentum, is formed from a nonperturbative extension of the two Feynman diagrams that contribute at one loop in perturbation theory. The required input is an existing ladder-rainbow model Bethe-Salpeter kernel from an approach based on the Dyson-Schwinger equations; no new parameters are introduced. The model includes an Ansatz for the triple-gluon vertex. Two of the three vertex amplitudes from the model provide a pointwise description of the recent quenched-lattice-QCD data. An estimate of the effects of quenching is made.
Probing the Gluon Self-Interaction in Light Mesons
Fischer, Christian S.; Williams, Richard
2009-09-18
We investigate masses and decay constants of light mesons from a coupled system of Dyson-Schwinger and Bethe-Salpeter equations. We explicitly take into account dominant non-Abelian contributions to the dressed quark-gluon vertex stemming from the gluon self-interaction. We construct the corresponding Bethe-Salpeter kernel that satisfies the axial-vector Ward-Takahashi identity. Our numerical treatment fully includes all momentum dependencies with all equations solved completely in the complex plane. This approach goes well beyond the rainbow-ladder approximation and permits us to investigate the influence of the gluon self-interaction on the properties of mesons. As a first result we find indications of a nonperturbative cancellation of the gluon self-interaction contributions and pion cloud effects in the mass of the rho meson.
Probing the gluon self-interaction in light mesons.
Fischer, Christian S; Williams, Richard
2009-09-18
We investigate masses and decay constants of light mesons from a coupled system of Dyson-Schwinger and Bethe-Salpeter equations. We explicitly take into account dominant non-Abelian contributions to the dressed quark-gluon vertex stemming from the gluon self-interaction. We construct the corresponding Bethe-Salpeter kernel that satisfies the axial-vector Ward-Takahashi identity. Our numerical treatment fully includes all momentum dependencies with all equations solved completely in the complex plane. This approach goes well beyond the rainbow-ladder approximation and permits us to investigate the influence of the gluon self-interaction on the properties of mesons. As a first result we find indications of a nonperturbative cancellation of the gluon self-interaction contributions and pion cloud effects in the mass of the rho meson.
Time evolution of the quark-gluon plasma
Cooper, F. |
1993-03-01
We review progress in our understanding the production and time evolution of the quark gluon plasma starting with boost invariant initial conditions in a filed theory model based on the Schwinger mechanism of particle production via tunneling.
Resummation and the gluon damping rate in hot QCD
Pisarski, R.D.
1990-08-01
At high temperature a consistent perturbative expansion requires the resummation of an infinite subset of loop corrections into an effective expansion. This effective exansion is used to compute the gluon damping rate at leading order. 25 refs.
Gluon condensate, Wilson loops and gauge/string duality
Andreev, Oleg; Zakharov, Valentin I.
2007-08-15
We test gauge/string duality by evaluating expectation values of small Wilson loops in pure Yang-Mills theories. On the gauge theory side, there exists a rich phenomenology. The dual formulation provides a universal language to evaluate the gluon condensate and quadratic correction in terms of the metric in the fifth coordinate. Quantitatively, the estimated value of the gluon condensate is approximately 0.010 GeV{sup 4}.
Unquenching effects in the quark and gluon propagator
NASA Astrophysics Data System (ADS)
Kamleh, Waseem; Bowman, Patrick O.; Leinweber, Derek B.; Williams, Anthony G.; Zhang, Jianbo
2007-11-01
In this work we examine the fat-link irrelevant clover (FLIC) overlap quark propagator and the gluon propagator on both dynamical and quenched lattices. The tadpole-improved Luscher-Weisz gauge action is used in both cases. The dynamical gauge fields use the FLIC fermion action for the sea quark contribution. We observe that the presence of sea quarks causes a suppression of the mass function, quark renormalization function, and gluon dressing function in the infrared. The ultraviolet physics is unaffected.
Study of leading hadrons in gluon and quark fragmentation
NASA Astrophysics Data System (ADS)
Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.; Delphi Collaboration
2006-12-01
The study of quark jets in e+e- reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected by the DELPHI experiment in the LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are defined by requiring a rapidity gap and their sum of charges is studied. An excess of leading systems with total charge zero is found for gluon jets in all cases, when compared to Monte Carlo simulations with JETSET (with and without Bose-Einstein correlations included) and ARIADNE. The corresponding leading systems of quark jets do not exhibit such an excess. The influence of the gap size and of the gluon purity on the effect is studied and a concentration of the excess of neutral leading systems at low invariant masses (≲ 2 GeV /c2) is observed, indicating that gluon jets might have an additional hitherto undetected fragmentation mode via a two-gluon system. This could be an indication of a possible production of gluonic states as predicted by QCD.
Study of leading hadrons in gluon and quark fragmentation
NASA Astrophysics Data System (ADS)
DELPHI Collaboration; Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.
2006-12-01
The study of quark jets in ee reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected by the DELPHI experiment in the LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are defined by requiring a rapidity gap and their sum of charges is studied. An excess of leading systems with total charge zero is found for gluon jets in all cases, when compared to Monte Carlo simulations with JETSET (with and without Bose Einstein correlations included) and ARIADNE. The corresponding leading systems of quark jets do not exhibit such an excess. The influence of the gap size and of the gluon purity on the effect is studied and a concentration of the excess of neutral leading systems at low invariant masses (≲2 GeV/c) is observed, indicating that gluon jets might have an additional hitherto undetected fragmentation mode via a two-gluon system. This could be an indication of a possible production of gluonic states as predicted by QCD.
Momentum broadening in unstable quark-gluon plasma
NASA Astrophysics Data System (ADS)
Carrington, M. E.; Mrówczyński, St.; Schenke, B.
2017-02-01
Quark-gluon plasma produced at the early stage of ultrarelativistic heavy-ion collisions is unstable, if weakly coupled, due to the anisotropy of its momentum distribution. Chromomagnetic fields are spontaneously generated and can reach magnitudes much exceeding typical values of the fields in equilibrated plasma. We consider a high-energy test parton traversing an unstable plasma that is populated with strong fields. We study the momentum broadening parameter q ̂ which determines the radiative energy loss of the test parton. We develop a formalism which gives q ̂ as the solution of an initial value problem, and we focus on extremely oblate plasmas which are physically relevant for relativistic heavy-ion collisions. The parameter q ̂ is found to be strongly dependent on time. For short times it is of the order of the equilibrium value, but at later times q ̂ grows exponentially due to the interaction of the test parton with unstable modes and becomes much bigger than the value in equilibrium. The momentum broadening is also strongly directionally dependent and is largest when the test parton velocity is transverse to the beam axis. Consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.
Heavy quarkonium moving in a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Escobedo, Miguel Angel; Giannuzzi, Floriana; Mannarelli, Massimo; Soto, Joan
2013-06-01
By means of effective field theory techniques, we study the modifications of some properties of weakly coupled heavy quarkonium states propagating through a quark-gluon plasma at temperatures much smaller than the heavy quark mass, mQ. Two different cases are considered, corresponding to two different hierarchies between the typical size of the bound state, r, the binding energy, E, the temperature, T, and the screening mass, mD. The first case corresponds to the hierarchy mQ≫1/r≫T≫E≫mD, relevant for moderate temperatures, and the second one to the hierarchy mQ≫T≫1/r, mD≫E, relevant for studying the dissociation mechanism. In the first case we determine the perturbative correction to the binding energy and to the decay width of states with arbitrary angular momentum, finding that the width is a decreasing function of the velocity. A different behavior characterizes the second kinematical case, where the width of s-wave states becomes a nonmonotonic function of the velocity, increasing at moderate velocities and decreasing in the ultrarelativistic limit. We obtain a simple analytical expression of the decay width for T≫1/r≫mD≫E at moderate velocities, and we derive the s-wave spectral function for the more general case T≫1/r, mD≫E. A brief discussion of the possible experimental signatures as well as a comparison with the relevant lattice data are also presented.
Phenomenological Review on Quark–Gluon Plasma: Concepts vs. Observations
NASA Astrophysics Data System (ADS)
Pasechnik, Roman; Šumbera, Michal
2017-01-01
In this review, we present an up-to-date phenomenological summary of research developments in the physics of the Quark--Gluon Plasma (QGP). A short historical perspective and theoretical motivation for this rapidly developing field of contemporary particle physics is provided. In addition, we introduce and discuss the role of the quantum chromodynamics (QCD) ground state, non-perturbative and lattice QCD results on the QGP properties, as well as the transport models used to make a connection between theory and experiment. The experimental part presents the selected results on bulk observables, hard and penetrating probes obtained in the ultra-relativistic heavy-ion experiments carried out at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (BNL RHIC) and CERN Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC) accelerators. We also give a brief overview of new developments related to the ongoing searches of the QCD critical point and to the collectivity in small ($p+p$ and $p+A$) systems.
Gluon-gluon contributions to W+ W- production and Higgs interference effects
Campbell, John M.; Ellis, R.Keith; Williams, Ciaran
2011-07-01
In this paper we complete our re-assessment of the production of W boson pairs at the LHC, by calculating analytic results for the gg {yields} W{sup +}W{sup -} {yields} {nu}{ell}{sup +}{ell}{sup -}{bar {nu}} process including the effect of massive quarks circulating in the loop. Together with the one-loop amplitudes containing the first two generations of massless quarks propagating in the loop, these diagrams can give a significant contribution with a large flux of gluons. One of the component parts of this calculation is the production of a standard model Higgs boson, gg {yields} H and its subsequent decay, H {yields} W{sup +}({yields} {nu}{ell}{sup +})W{sup -}({yields} {ell}{sup -}{bar {nu}}). We will quantify the importance of the interference between the Higgs boson production process and the gluon-induced continuum production in the context of searches for the Higgs boson at the Tevatron and the LHC. For instance, for m{sub H} < 140 GeV the effect of the interference typically results in around a 10% reduction in the expected number of Higgs signal events. The majority of this interference is due to non-resonant contributions. Therefore cuts on the transverse mass such as those currently used by the ATLAS collaboration reduce the destructive interference to about a 1% effect. We advocate that a cut on the maximum transverse mass be used in future Higgs searches in this channel.
NASA Technical Reports Server (NTRS)
VonGlahn, Uwe H.; Gelder, Thomas F.; Smyers, William H., Jr.
1955-01-01
A dye-tracer technique has been developed whereby the quantity of dyed water collected on a blotter-wrapped body exposed to an air stream containing a dyed-water spray cloud can be colorimetrically determined in order to obtain local collection efficiencies, total collection efficiency, and rearward extent of impingement on the body. In addition, a method has been developed whereby the impingement characteristics obtained experimentally for a body can be related to theoretical impingement data for the same body in order to determine the droplet size distribution of the impinging cloud. Several cylinders, a ribbon, and an aspirating device to measure cloud liquid-water content were used in the studies presented herein for the purpose of evaluating the dye-tracer technique. Although the experimental techniques used in the dye-tracer technique require careful control, the methods presented herein should be applicable for any wind tunnel provided the humidity of the air stream can be maintained near saturation.
Collective Flow signals the Quark Gluon Plasma
NASA Astrophysics Data System (ADS)
Bratkovskaya, E. L.; Bleicher, M.; Greiner, C.; Muronga, A.; Paech, K.; Reiter, M.; Scherer, S.; Soff, S.; Xu, Z.; Zeeb, G.; Zschiesche, D.; Tavares, B.; Portugal, L.; Aguiar, C.; Kodama, T.; Grassi, F.; Hama, Y.; Osada, T.; Sokolowski, O.; Werner, K.; Gallmeister, K.; Cassing, W.; Stöcker, H.
2004-12-01
A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 AṡGeV: here the hydrodynamic model has predicted the collapse of the v1-flow and of the v2-flow at ˜ 10 AṡGeV; at 40 AṡGeV it has been recently observed by the NA49 collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density ρB. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Additionally, detailed transport studies show that the away-side jet suppression can only partially (< 50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e. at μB ≈ 400 MeV (y ≈ 4 - 5), where the collapse of the proton flow should be seen in analogy to the 40 AṡGeV data. The study of Jet-Wake-riding potentials and Bow shocks — caused by jets in the QGP formed at RHIC — can give further information on the equation of state (EoS) and transport coefficients of the Quark Gluon Plasma (QGP).
NASA Astrophysics Data System (ADS)
Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; da Silva, T.; Da Silva, W.; Della Ricca, G.; De Angelis, A.; De Boer, W.; De Clercq, C.; De Lotto, B.; De Maria, N.; De Min, A.; de Paula, L.; Di Ciaccio, L.; Di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nemecek, S.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; Van Dam, P.; Van Eldik, J.; van Remortel, N.; Van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.
2011-02-01
The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly decaying b-hadrons, EB^{weak}. The average value of x^{weak}B = EB^{weak}/E_{beam} is measured to be 0.699±0.011. The resulting x^{weak}B distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of b-hadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data: a= 1.84^{+0.23}_{-0.21}quadandquad b=0.642^{+0.073}_{-0.063} GeV^{-2}, with a correlation factor ρ=92.2%. Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of x^{weak}B is found to be 0.7092±0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained: a= 1.48^{+0.11}_{-0.10}quadandquad b=0.509^{+0.024}_{-0.023} GeV^{-2}, with a correlation factor ρ=92.6%.
de Araujo-Barbosa, Paulo Henrique Ferreira; de Menezes, Lidiane Teles; Costa, Abraão Souza; Couto Paz, Clarissa Cardoso Dos Santos; Fachin-Martins, Emerson
2015-05-01
Described as an alternative way of assessing weight-bearing asymmetries, the measures obtained from digital scales have been used as an index to classify weight-bearing distribution. This study aimed to describe the intra-test and the test/retest reliability of measures in subjects with and without hemiparesis during quiet stance. The percentage of body weight borne by one limb was calculated for a sample of subjects with hemiparesis and for a control group that was matched by gender and age. A two-way analysis of variance was used to verify the intra-test reliability. This analysis was calculated using the differences between the averages of the measures obtained during single, double or triple trials. The intra-class correlation coefficient (ICC) was utilized and data plotted using the Bland-Altman method. The intra-test analysis showed significant differences, only observed in the hemiparesis group, between the measures obtained by single and triple trials. Excellent and moderate ICC values (0.69-0.84) between test and retest were observed in the hemiparesis group, while for control groups ICC values (0.41-0.74) were classified as moderate, progressing from almost poor for measures obtained by a single trial to almost excellent for those obtained by triple trials. In conclusion, good reliability ranging from moderate to excellent classifications was found for participants with and without hemiparesis. Moreover, an improvement of the repeatability was observed with fewer trials for participants with hemiparesis, and with more trials for participants without hemiparesis.
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.
AdS/QCD, Light-Front Holography, and Sublimated Gluons
Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.
2012-02-16
The gauge/gravity duality leads to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian - 'Light-Front Holography', which provides a Lorentz-invariant first-approximation to QCD, and successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schroedinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holography connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable {zeta} in 3+1 space at fixed light-front time. A key feature is the determination of the frame-independent light-front wavefunctions of hadrons - the relativistic analogs of the Schroedinger wavefunctions of atomic physics which allow one to compute form factors, transversity distributions, spin properties of the valence quarks, jet hadronization, and other hadronic observables. One thus obtains a one-parameter color-confining model for hadron physics at the amplitude level. AdS/QCD also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function with an infrared fixed point which agrees with the effective coupling a{sub g1} (Q{sup 2}) extracted from measurements of the Bjorken sum rule below Q{sup 2} < 1 GeV{sup 2}. This is consistent with a flux-tube interpretation of QCD where soft gluons with virtualities Q{sup 2} < 1 GeV{sup 2} are sublimated into a color-confining potential for quarks. We discuss a number of phenomenological hadronic properties which support this picture.
The consequences of SU (3) colorsingletness, Polyakov Loop and Z (3) symmetry on a quark-gluon gas
NASA Astrophysics Data System (ADS)
Aminul Islam, Chowdhury; Abir, Raktim; Mustafa, Munshi G.; Ray, Rajarshi; Ghosh, Sanjay K.
2014-02-01
Based on quantum statistical mechanics, we show that the SU(3) color singlet ensemble of a quark-gluon gas exhibits a Z(3) symmetry through the normalized character in fundamental representation and also becomes equivalent, within a stationary point approximation, to the ensemble given by Polyakov Loop. In addition, a Polyakov Loop gauge potential is obtained by considering spatial gluons along with the invariant Haar measure at each space point. The probability of the normalized character in SU(3) vis-a-vis a Polyakov Loop is found to be maximum at a particular value, exhibiting a strong color correlation. This clearly indicates a transition from a color correlated to an uncorrelated phase, or vice versa. When quarks are included in the gauge fields, a metastable state appears in the temperature range 145 ⩽ T(MeV) ⩽ 170 due to the explicit Z(3) symmetry breaking in the quark-gluon system. Beyond T ⩾ 170 MeV, the metastable state disappears and stable domains appear. At low temperatures, a dynamical recombination of ionized Z(3) color charges to a color singlet Z(3) confined phase is evident, along with a confining background that originates due to the circulation of two virtual spatial gluons, but with conjugate Z(3) phases in a closed loop. We also discuss other possible consequences of the center domains in the color deconfined phase at high temperatures. Communicated by Steffen Bass
Comparison of jet quenching formalisms for a quark-gluon plasma ``brick''
NASA Astrophysics Data System (ADS)
Armesto, Nestor; Cole, Brian; Gale, Charles; Horowitz, William A.; Jacobs, Peter; Jeon, Sangyong; van Leeuwen, Marco; Majumder, Abhijit; Müller, Berndt; Qin, Guang-You; Salgado, Carlos A.; Schenke, Björn; Verweij, Marta; Wang, Xin-Nian; Wiedemann, Urs Achim
2012-12-01
We review the currently available formalisms for radiative energy loss of a high-momentum parton in a dense strongly interacting medium. The underlying theoretical framework of the four commonly used formalisms is discussed and the differences and commonalities between the formalisms are highlighted. A quantitative comparison of the single-gluon emission spectra as well as the energy-loss distributions is given for a model system consisting of a uniform medium with a fixed length of L=2 fm and L=5 fm (the “Brick”). Sizable quantitative differences are found. The largest differences can be attributed to specific approximations that are made in the calculation of the radiation spectrum.
To What Extent is Gluon Confinement an Empirical Fact?
NASA Astrophysics Data System (ADS)
Delgado, R. L.; Hidalgo-Duque, Carlos; Llanes-Estrada, Felipe J.
2013-11-01
Experimental verifications of confinement in hadron physics have established the absence of charges with a fraction of the electron's charge by studying the energy deposited in ionization tracks at high energies, and performing Millikan experiments with charged droplets at rest. These experiments test only the absence of particles with fractional charge in the asymptotic spectrum, and thus "Quark" Confinement. However what theory suggests is that Color is confined, that is, all asymptotic particles are color singlets. Since QCD is a non-Abelian theory, the gluon force carriers (indirectly revealed in hadron jets) are colored. We empirically examine what can be said about gluon confinement based on the lack of detection of appropriate events, aiming at an upper bound for high-energy free-gluon production.
NASA Technical Reports Server (NTRS)
Siemers, P. M., III; Henry, M. W.
1986-01-01
Pressure distribution test data obtained on a 0.10-scale model of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests were completed in the AEDC 16T Propulsion Wind Tunnel. The 0.10-scale model was tested at angles of attack from -2 deg to 18 deg and angles of side slip from -6 to 6 deg at Mach numbers from 0.25 to 1/5 deg. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS orifices, the wind-tunnel model was also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations that existed on the Space Shuttle Orbiter Columbia (OV-102) during the Orbiter Flight Test program. This DFI simulation has provided a means of comparisons between reentry flight pressure data and wind-tunnel and computational data.
Gluon mass generation in the massless bound-state formalism
NASA Astrophysics Data System (ADS)
Ibañez, D.; Papavassiliou, J.
2013-02-01
We present a detailed, all-order study of gluon mass generation within the massless bound-state formalism, which constitutes the general framework for the systematic implementation of the Schwinger mechanism in non-Abelian gauge theories. The main ingredient of this formalism is the dynamical formation of bound states with vanishing mass, which give rise to effective vertices containing massless poles; these latter vertices, in turn, trigger the Schwinger mechanism, and allow for the gauge-invariant generation of an effective gluon mass. This particular approach has the conceptual advantage of relating the gluon mass directly to quantities that are intrinsic to the bound-state formation itself, such as the “transition amplitude” and the corresponding “bound-state wave function.” As a result, the dynamical evolution of the gluon mass is largely determined by a Bethe-Salpeter equation that controls the dynamics of the relevant wave function, rather than the Schwinger-Dyson equation of the gluon propagator, as happens in the standard treatment. The precise structure and field-theoretic properties of the transition amplitude are scrutinized in a variety of independent ways. In particular, a parallel study within the linear-covariant (Landau) gauge and the background-field method reveals that a powerful identity, known to be valid at the level of conventional Green’s functions, also relates the background and quantum transition amplitudes. Despite the differences in the ingredients and terminology employed, the massless bound-state formalism is absolutely equivalent to the standard approach based on Schwinger-Dyson equations. In fact, a set of powerful relations allows one to demonstrate the exact coincidence of the integral equations governing the momentum evolution of the gluon mass in both frameworks.
Delepine, P; Montier, T; Guillaume, C; Vaysse, L; Le Pape, A; Ferec, C
2002-06-01
Gene transfer to the lung can be achieved via a systemic, that targets the endothelium, or local, that targets the epithelium, delivery route. In the present study, we followed the distribution of a plasmid after transfection using some of our phosphonolipids, which have previously shown their efficiency in transfecting mouse lungs. The plasmid was radiolabeled and varying combinations of plasmid/phosphonolipid were administered by intravenous injection, or by endotracheal spray. The distribution of radioactive labeling was observed over a time course using a gamma-camera. These images were then correlated with the results for luciferase expression levels in the lungs. In each case, lungs were well targeted. However, whereas an intravenous injection reaches all of the lung immediately, progressive diffusion occurs when the plasmid/phosphonolipid is administered via an aerosol. Elimination of the radioactivity associated with plasmid occurs via the urinary tract after intravenous injections, and via the feces using the aerosol delivery approach. The radioactivity detected in the lungs correlated strongly with transgene expression. Thus, such an imaging technique is a powerful strategy to predict the formulation that will generate the best transfection efficiency. This study reveals that scintigraphic imaging permits both validation of the administration method and the results obtained for each animal, thereby reducing the statistical variability of in vivo experiments.
Quarkonium in a weakly-coupled quark-gluon plasma
Vairo, Antonio
2010-12-22
We report about a recent calculation of the heavy quarkonium mass and decay width in a quark-gluon plasma, whose temperature T and screening mass m{sub D} satisfy the hierarchy m{alpha}{sub s}>>T>>m{alpha}{sub s}{sup 2}>>m{sub D}, m being the heavy-quark mass, up to order m{alpha}{sub s}{sup 5}. The calculation may be relevant to understand the behavior of the {Upsilon}(1S) in a quark-gluon plasma at present-day colliders.
Further evidence for zero crossing on the three gluon vertex
NASA Astrophysics Data System (ADS)
Duarte, Anthony G.; Oliveira, Orlando; Silva, Paulo J.
2016-10-01
The three gluon one particle irreducible function is investigated using lattice QCD simulations over a large region of momentum in the Landau gauge for four-dimensional pure Yang-Mills equations and the SU(3) gauge group. The results favor a zero crossing of the gluon form factor for momenta in the range 220-260 MeV. This zero crossing is required to happen in order to have a properly defined set of Dyson-Schwinger equations. It is also shown that in the high momentum region the lattice results are compatible with the predictions of renormalization group improved perturbation theory.
Bottomonia suppression in an anisotropic quark-gluon plasma
NASA Astrophysics Data System (ADS)
Ryblewski, Radoslaw
2017-03-01
A brief review of recent studies on suppression of bottomonia in an anisotropic quark-gluon plasma created in heavy-ion collisions at the LHC is presented. A reasonable agreement between the model predictions for the inclusive RAA suppression factor and the preliminary CMS experimental data is found. The values of the shear viscosity to the entropy density ratio extracted from the comparison with the data lie between one and two times the gauge/gravity duality lower bound. These values agree very well with the fluid dynamical fits to the light hadron correlation data and confirm that the quark-gluon plasma is a nearly-perfect fluid.
Drell-Yan hadron tensor: Contour gauge and gluon propagator
NASA Astrophysics Data System (ADS)
Anikin, I. V.; Cherednikov, I. O.; Teryaev, O. V.
2017-02-01
We consider the gauge invariant Drell-Yan hadron tensor which includes the standard and nonstandard diagram contributions. The nonstandard diagram contribution appeared owing to the complexity of the twist three BV(x1,x2)-function where the gluon pole manifests. We use the contour gauge conception which allows us to fix easily the spurious uncertainties in the gluon propagator. The contour gauge condition is generated by the corresponding Wilson lines in both the standard and nonstandard diagrams. We demonstrate the substantial role of the nonstandard diagram for forming of the relevant contour in the Wilson path-ordered exponential that leads to the spurious singularity fixing.
Quark-gluon vertex in arbitrary gauge and dimension
NASA Astrophysics Data System (ADS)
Davydychev, A. I.; Osland, P.; Saks, L.
2001-01-01
One-loop off-shell contributions to the quark-gluon vertex are calculated, in an arbitrary covariant gauge and in arbitrary space-time dimension, including quark-mass effects. It is shown how one can get results for all on-shell limits of interest directly from the off-shell expressions. In order to demonstrate that the Ward-Slavnov-Taylor identity for the quark-gluon vertex is satisfied, we have also calculated the corresponding one-loop contribution involving the quark-quark-ghost-ghost vertex.
Viscous quark-gluon plasma model through fluid QCD approach
Djun, T. P.; Soegijono, B.; Mart, T.; Handoko, L. T. E-mail: Laksana.tri.handoko@lipi.go.id
2014-09-25
A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, are discussed. The energy momentum tensor that is relevant to the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.
Impact factors for Reggeon-gluon transition in N=4 SYM with large number of colours
NASA Astrophysics Data System (ADS)
Fadin, V. S.; Fiore, R.
2014-06-01
We calculate impact factors for Reggeon-gluon transition in supersymmetric Yang-Mills theory with four supercharges at large number of colours Nc. In the next-to-leading order impact factors are not uniquely defined and must accord with BFKL kernels and energy scales. We obtain the impact factor corresponding to the kernel and the energy evolution parameter, which is invariant under Möbius transformation in momentum space, and show that it is also Möbius invariant up to terms taken into account in the BDS ansatz.
Perkins, W G; Lucero, D A
2001-02-01
The US Department of Energy (DOE), with technical assistance from Sandia National Laboratories, has successfully received EPA certification and opened the Waste Isolation Pilot Plant (WIPP), a nuclear waste disposal facility located approximately 42 km east of Carlsbad, NM. Performance assessment (PA) analyses indicate that human intrusions by inadvertent, intermittent drilling for resources provide the only credible mechanisms for significant releases of radionuclides from the disposal system. For long-term brine releases, migration pathways through the permeable layers of rock above the Salado formation are important. Major emphasis is placed on the Culebra Member of the Rustler Formation because this is the most transmissive geologic layer overlying the WIPP site. In order to help quantify parameters for the calculated releases, radionuclide transport experiments have been carried out using intact-core columns obtained from the Culebra dolomite member of the Rustler Formation within the WIPP site. This paper deals primarily with results of analyses for 241Pu and 241Am distributions developed during transport experiments in one of these cores. Transport experiments were done using a synthetic brine that simulates Culebra brine at the core recovery location (the WIPP air-intake shaft (AIS)). Hydraulic characteristics (i.e., apparent porosity and apparent dispersion coefficient) for intact-core columns were obtained via experiments using the conservative tracer 22Na. Elution experiments carried out over periods of a few days with tracers 232U and 239Np indicated that these tracers were weakly retarded as indicated by delayed elution of the species. Elution experiments with tracers 241Pu and 241Am were attempted but no elution of either species has been observed to date, including experiments of many months' duration. In order to quantify retardation of the non-eluted species 241Pu and 241Am after a period of brine flow, non-destructive and destructive analyses of
NASA Astrophysics Data System (ADS)
Perkins, W. George; Lucero, Daniel A.
2001-02-01
The US Department of Energy (DOE), with technical assistance from Sandia National Laboratories, has successfully received EPA certification and opened the Waste Isolation Pilot Plant (WIPP), a nuclear waste disposal facility located approximately 42 km east of Carlsbad, NM. Performance assessment (PA) analyses indicate that human intrusions by inadvertent, intermittent drilling for resources provide the only credible mechanisms for significant releases of radionuclides from the disposal system. For long-term brine releases, migration pathways through the permeable layers of rock above the Salado formation are important. Major emphasis is placed on the Culebra Member of the Rustler Formation because this is the most transmissive geologic layer overlying the WIPP site. In order to help quantify parameters for the calculated releases, radionuclide transport experiments have been carried out using intact-core columns obtained from the Culebra dolomite member of the Rustler Formation within the WIPP site. This paper deals primarily with results of analyses for 241Pu and 241Am distributions developed during transport experiments in one of these cores. Transport experiments were done using a synthetic brine that simulates Culebra brine at the core recovery location (the WIPP air-intake shaft (AIS)). Hydraulic characteristics (i.e., apparent porosity and apparent dispersion coefficient) for intact-core columns were obtained via experiments using the conservative tracer 22Na. Elution experiments carried out over periods of a few days with tracers 232U and 239Np indicated that these tracers were weakly retarded as indicated by delayed elution of the species. Elution experiments with tracers 241Pu and 241Am were attempted but no elution of either species has been observed to date, including experiments of many months' duration. In order to quantify retardation of the non-eluted species 241Pu and 241Am after a period of brine flow, non-destructive and destructive analyses of
Tranchepain, Frédéric; Deschrevel, Brigitte; Courel, Marie-Noëlle; Levasseur, Nicolas; Le Cerf, Didier; Loutelier-Bourhis, Corinne; Vincent, Jean-Claude
2006-01-15
Hyaluronan (HA) has different biological functions according to its molar mass; short HA fragments are involved in inflammation processes and angiogenesis, whereas native HA is not. Physicochemically, studies of native HA hydrolysis catalyzed by bovine testicular hyaluronidase (HAase) have suggested that kinetic parameters depend on HA chain length. To study the influence of HA chain length in more detail, and to try to correlate the physicochemical and biological properties of HA, HA hydrolysis catalyzed by HAase was used in a new procedure to obtain HA fragments of different molar masses. HA fragments (10-mg scale) with a molar mass from 800 to 300,000 g mol(-1) were prepared, purified using low-pressure size exclusion chromatography (SEC), lyophilized, and characterized in molar mass by either mass spectrometry or HPLC-SEC-multiangle laser light scattering. The polydispersity index of the purified fractions was less than 1.25. The complete set of HA standards obtained was used to calibrate our routine HPLC-SEC device using only a refractive index (RI) detector. We showed that the N-acetyl-d-glucosamine reducing end assay and the calibrated HPLC-SEC-RI gave equivalent kinetic data. In addition, the HPLC-SEC-RI furnished the mass distribution of the polysaccharide during its hydrolysis.
Gluon condensate in a pion superfluid beyond the mean-field approximation
Jiang Yin; Zhuang Pengfei
2011-03-15
We study gluon condensate in a pion superfluid by calculating the equation of state of the system in the Nambu-Jona-Lasinio model. While in mean-field approximation the growing pion condensate leads to an increasing gluon condensate, meson fluctuations reduce the gluon condensate, and the broken scalar symmetry can be smoothly restored at finite isospin density.
Bali, Gunnar S.; Pineda, Antonio
2016-01-22
We study the operator product expansion of the plaquette (gluon condensate) and the self-energy of an infinitely heavy quark. We first compute their perturbative expansions to order α{sup 35} and α{sup 20}, respectively, in the lattice scheme. In both cases we reach the asymptotic regime where the renormalon behavior sets in. Subtracting the perturbative series, we obtain the leading non-perturbative corrections of their respective operator product expansions. In the first case we obtain the gluon condensate and in the second the binding energy of the heavy quark in the infinite mass limit. The results are fully consistent with the expectations from renormalons and the operator product expansion.
Kannamkumarath, Sasi S; Wrobel, Katarzyna; Wuilloud, Rodolfo G
2005-03-31
In this work, size exclusion chromatography (SEC) with UV and inductively coupled plasma mass spectrometry (ICP-MS) detection was used to study the association of selenium to proteins present in Brazil nuts (Bertholletia excelsa) under five different extraction conditions. As expected, better solubilization of proteins was observed using 0.05molL(-1) sodium hydroxide and 1% sodium dodecylsulfate (SDS) in Tris/HCl buffer (0.05molL(-1), pH 8) as compared to 0.05molL(-1) HCl, 0.05molL(-1) Tris/HCl or hot water (60 degrees C). Due to non-destructive character of Tris-SDS treatment, this was applied for studying molecular weight (MW) distribution patterns of selenium-containing nut proteins. Three different SEC columns were used for obtaining complete MW distribution of selenium: Superdex 75, Superdex Peptide, and Superdex 200 were tested with 50mmolL(-1) Tris buffer (pH 8), 150mmolL(-1) ammonium bicarbonate buffer (pH 7.8), phosphate (pH 7.5), and CAPS (pH 10.0) mobile phases. Using Superdex 200 column, the elution of at least three MW fractions was observed with UV detection (200-10kDa) and ICP-MS chromatogram showed the co-elution of selenium with the two earlier fractions. The apparent MWs of these selenium-containing fractions were respectively about 107 and 50kDa, as evaluated from the column calibration. For further characterization of individual selenium species, the defatted nuts were hydrolyzed with proteinase K and analyzed by capillary electrophoresis (CE) with ICP-MS detection. The suitability of CE for the separation of selenite, selenate, selenocystine and selenomethionine in the presence of the nut sample matrix is demonstrated. Complete separation of the above mentioned selenium species was obtained within a migration time of 7min. In the analysis of nut extracts with CE-ICP-MS, selenium was found to be present mainly as selenomethionine.
Creating the Primordial Quark-Gluon Plasma at the LHC
NASA Astrophysics Data System (ADS)
Harris, John W.
2013-04-01
Ultra-relativistic collisions of heavy ions at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) create an extremely hot system at temperatures (T) expected only within the first microseconds after the Big Bang. At these temperatures (T ˜ 2 x 10^12 K), a few hundred thousand times hotter than the sun's core, the known ``elementary'' particles cannot exist and matter ``melts'' to form a ``soup'' of quarks and gluons, called the quark-gluon plasma (QGP). This ``soup'' flows easily, with extremely low viscosity, suggesting a nearly perfect hot liquid of quarks and gluons. Furthermore, the liquid is dense, highly interacting and opaque to energetic probes (fast quarks or gluons). RHIC has been in operation for twelve years and has established an impressive set of findings. Recent results from heavy ion collisions at the LHC extend the study of the QGP to higher temperatures and harder probes, such as jets (energetic clusters of particles), particles with extremely large transverse momenta and those containing heavy quarks. I will present a motivation for physics in the field and an overview of the new LHC heavy ion results in relation to results from RHIC.
Nonlinear Landau damping in quark-gluon plasma
NASA Astrophysics Data System (ADS)
Xiaofei, Zhang; Jiarong, Li
1995-08-01
The semiclassical kinetic equations for the quark-gluon plasma (QGP) are discussed by the multiple time-scale method. The mechanism of nonlinear Landau damping owing to non-Abelian and nonlinear wave-particle interactions in QGP is investigated, and the nonlinear Landau damping rate for the longitudinal color eigenwaves in the long-wavelength limit is calculated.
Holographic Wilson loops in anisotropic quark-gluon plasma.
NASA Astrophysics Data System (ADS)
Ageev, Dmitry
2016-10-01
The nonequilibrium properties of the anisotropic quark-gluon plasma are condidered from the holographic viewpoint. Lifshitz-like solution is considered as a holographic dual of anisotropic QGP. The black brane formation in such background is considered as a thermalization in dual theory. As a probe of thermalization we consider rectangular spatial Wilson loops with different orientation.
Probing Quark-Gluon-Plasma properties with a Bayesian model-to-data comparison
NASA Astrophysics Data System (ADS)
Cai, Tianji; Bernhard, Jonah; Ke, Weiyao; Bass, Steffen; Duke QCD Group Team
2016-09-01
Experiments at RHIC and LHC study a special state of matter called the Quark Gluon Plasma (QGP), where quarks and gluons roam freely, by colliding relativistic heavy-ions. Given the transitory nature of the QGP, its properties can only be explored by comparing computational models of its formation and evolution to experimental data. The models fall, roughly speaking, under two categories-those solely using relativistic viscous hydrodynamics (pure hydro model) and those that in addition couple to a microscopic Boltzmann transport for the later evolution of the hadronic decay products (hybrid model). Each of these models has multiple parameters that encode the physical properties we want to probe and that need to be calibrated to experimental data, a task which is computationally expensive, but necessary for the knowledge extraction and determination of the models' quality. Our group has developed an analysis technique based on Bayesian Statistics to perform the model calibration and to extract probability distributions for each model parameter. Following the previous work that applies the technique to the hybrid model, we now perform a similar analysis on a pure-hydro model and display the posterior distributions for the same set of model parameters. We also develop a set of criteria to assess the quality of the two models with respect to their ability to describe current experimental data. Funded by Duke University Goldman Sachs Research Fellowship.
Exploring dynamical gluon mass generation in three dimensions
NASA Astrophysics Data System (ADS)
Cornwall, John M.
2016-01-01
We reexamine the d =3 dynamical gluon mass problem in pure-glue non-Abelian S U (N ) gauge theories, paying particular attention to the observed (in Landau gauge) violation of positivity for the spectral function of the gluon propagator. This is expressed as a large bulge in the propagator at small momentum, due to the d =3 avatar of asymptotic freedom. Mass is defined through m-2=Δ (p =0 ) , where Δ (p ) is the scalar function for the gluon propagator in some chosen gauge; it is not a pole mass and is generally gauge dependent, except in the gauge-invariant pinch technique (PT). We truncate the PT equations with a recently proposed method called the vertex paradigm that automatically satisfies the QED-like Ward identity relating the three-gluon PT vertex function with the PT propagator. The mass is determined by a homogeneous Bethe-Salpeter equation involving this vertex and propagator. This gap equation also encapsulates the Bethe-Salpeter equation for the massless scalar excitations, essentially Nambu-Goldstone fields, that necessarily accompany gauge-invariant gluon mass. The problem is to find a good approximate value for m and at the same time explain the bulge, which by itself leads, in the gap equation for the gluon mass, to excessively large values for the mass. Our point is not to give a high-accuracy determination of m but to clarify the way in which the propagator bulge and a fairly accurate estimate of m can coexist, and we use various approximations that illustrate the underlying mechanisms. The most critical point is to satisfy the Ward identity. In the PT we estimate a gauge-invariant dynamical gluon mass of m ≈N g2/(2.48 π ) . We translate these results to the Landau gauge using a background-quantum identity involving a dynamical quantity κ such that m =κ mL , where mL-2≡ΔL(p =0 ) . Given our estimates for m , κ , the relation is fortuitously well satisfied for S U (2 ) lattice data.
NASA Technical Reports Server (NTRS)
Siemers, P. M., III; Henry, M. W.
1986-01-01
Pressure distribution test data obtained on a 0.10-scale model of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests were completed in the Ames Unitary Wind Tunnel (UPWT). The UPWT tests were conducted in two different test sections operating in the continuous mode, the 8 x 7 feet and 9 x 7 feet test sections. Each test section has its own Mach number range, 1.6 to 2.5 and 2.5 to 3.5 for the 9 x 7 feet and 8 x 7 feet test section, respectively. The test Reynolds number ranged from 1.6 to 2.5 x 10 to the 6th power ft and 0.6 to 2.0 x 10 to the 6th power ft, respectively. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS orifices, the wind-tunnel model was also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations that existed on the Space Shuttle Columbia (OV-102) during the Orbiter Flight test program. This DFI simulation has provided a means for comparisons between reentry flight pressure data and wind-tunnel and computational data.
QCD in the nuclear medium and effects due to Cherenkov gluons
Dremin, I. M.
2010-04-15
The equations of in-medium gluodynamics are proposed. Their classical lowest-order solution is explicitly shown for a color charge moving with constant speed. For chromopermittivity larger than 1 it describes emission of Cherenkov gluons resembling results of classical electrodynamics. The values of the real and imaginary parts of the chromopermittivity are obtained from the fits to experimental data on the double-humped structure around the away-side jet obtained at RHIC. The dispersion of the chromopermittivity is predicted by comparing the RHIC, SPS, and cosmic-ray data. This is important for LHC experiments. Cherenkov gluons may be responsible for the asymmetry of dilepton mass spectra near {rho} meson observed in the SPS experiment with excess in the low-mass wing of the resonance. This feature is predicted to be common for all resonances. The 'color rainbow' quantum effect might appear according to higher-order terms of in-medium QCD if the chromopermittivity depends on color.
NASA Astrophysics Data System (ADS)
Pagnoni, G.; Tinti, S.; Armigliato, A.; Tonini, R.; Gallazzi, S.; Manucci, A.; Zaniboni, F.
2006-12-01
study the run-up heights. In both cases, we divide the earthquake fault in a given number of sub-faults, and then compute the tsunami generated by each sub-fault by means of two different codes: a finite-difference code implementing the linear shallow-water equations for the ocean-wide domain, and a finite-element code solving the non-linear version of the same equations in the local domain. In the case of the altimeter data, the adopted inversion technique is an implementation of the classical generalized linear least-squares theory. A more sophisticated technique, allowing one to determine also different amplification factors along different coastal segments, is employed to invert run-up data. We discuss the slip distributions obtained separately in the two approaches, and compare the results with those retrieved by modeling seismic and geodetic data.
Rapidity distributions in Drell-Yan and Higgs productions at threshold to third order in QCD.
Ahmed, Taushif; Mandal, M K; Rana, Narayan; Ravindran, V
2014-11-21
We present the threshold N(3)LO perturbative QCD corrections to the rapidity distributions of dileptons in the Drell-Yan process and Higgs boson in gluon fusion. Sudakov resummation of QCD amplitudes, renormalization group invariance, and the mass factorization theorem provide useful guidelines to obtain them in an elegant manner. We use various state of the art three loop results that have been recently available to obtain these distributions. For the Higgs boson, we demonstrate numerically the importance of these corrections at the LHC.
NASA Astrophysics Data System (ADS)
Shurshakov, Vyacheslav; Nikolaev, Igor; Kartsev, Ivan; Tolochek, Raisa; Lyagushin, Vladimir
The tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS in Matroshka-R experiment for more than 10 years. Both passive and active space radiation detectors can be located inside the phantom and on its surface. Due to the specially chosen phantom shape and size, the chord length distributions of the detector locations are attributed to self-shielding properties of the critical organs in a human body. Originally the spherical phantom was installed in the star board crew cabin of the ISS Service Module, then in the Piers-1, MIM-2, and MIM-1 modules of the ISS Russian segment, and finally in JAXA Kibo module. Total duration of the detector exposure is more than 2000 days in 9 sessions of the space experiment. In the first phase of the experiment with the spherical phantom the dose measurements were realized with only passive detectors (thermoluminescent and solid state track detectors). The detectors are placed inside the phantom along the axes of 20 containers and on the phantom outer surface in 32 pockets of the phantom jacket. After each session the passive detectors are returned to the ground. The results obtained show the dose difference on the phantom surface as much as a factor of 2, the highest dose being usually observed close to the outer wall of the compartment, and the lowest dose being in the opposite location along the phantom diameter. However, because of the ISS module shielding properties an inverse dose distribution in a human body can be observed when the dose rate maximum is closer to the geometrical center of the module. Maximum dose rate measured in the phantom is obviously due to the action of two radiation sources, namely, galactic cosmic rays (GCR) and Earth’ radiation belts. Minimum dose rate is produced mainly by the strongly penetrating GCR particles and is mostly observed behind more than 5 g/cm2 tissue shielding. Critical organ doses, mean
Longitudinal oscillations and linear Landau damping in quark-gluon plasma.
Murtaza, G; Khattak, N A D; Shah, H A
2003-12-01
On the basis of the semiclassical kinetic Vlasov equation for quark-gluon plasma and the Yang-Mills equation in covariant gauge, linear Landau damping for electrostatic perturbations such as Langmuir waves is investigated for the extreme-relativistic and strongly relativistic cases. It has been observed that for the extreme-relativistic case, wherein the thermal speed of the particles exceeds the phase velocity of the perturbations, the linear Landau damping is absent as has been reported in the literature. However, a departure from extreme-relativistic case generates an imaginary component of the frequency giving rise to linear Landau damping effect. The relevant integral for the conductivity tensor has been evaluated and the dispersion relation for the longitudinal part of the oscillation was obtained. Further, it is also noted that both the real part of the oscillation frequency and the damping rate are sensitive to the choice of the wave number k and the Debye length lambda(D) associated with quark-gluon plasma.
Magnetic phase diagram of dense holographic multiquarks in the quark-gluon plasma
NASA Astrophysics Data System (ADS)
Burikham, Piyabut
2011-05-01
We study phase diagram of the dense holographic gauge matter in the Sakai-Sugimoto model in the presence of the magnetic field above the deconfinement temperature. Even above the deconfinement, quarks could form colour bound states through the remaining strong interaction if the density is large. We demonstrate that in the presence of the magnetic field for a sufficiently large baryon density, the multiquark-pion gradient (MQ-∇ φ) phase is more thermodynamically preferred than the chiral-symmetric quark-gluon plasma. The phase diagrams between the holographic multiquark and the chiral-symmetric quark-gluon plasma phase are obtained at finite temperature and magnetic field. In the mixed MQ-∇ φ phase, the pion gradient induced by the external magnetic field is found to be a linear response for small and moderate field strengths. Its population ratio decreases as the density is raised and thus the multiquarks dominate the phase. Temperature dependence of the baryon chemical potential, the free energy and the linear pion gradient response of the multiquark phase are well approximated by a simple q analytic function sqrt {{1 - {{T^6}}/{T_0^6}}} inherited from the metric of the holographic background.
Angular correlations in gluon production at high energy
Kovner, Alex; Lublinsky, Michael
2011-02-01
We present a general, model independent argument demonstrating that gluons produced in high energy hadronic collision are necessarily correlated in rapidity and also in the emission angle. The strength of the correlation depends on the process and on the structure/model of the colliding particles. In particular we argue that it is strongly affected (and underestimated) by factorized approximations frequently used to quantify the effect.
Quark-gluon plasma phase transition using cluster expansion method
NASA Astrophysics Data System (ADS)
Syam Kumar, A. M.; Prasanth, J. P.; Bannur, Vishnu M.
2015-08-01
This study investigates the phase transitions in QCD using Mayer's cluster expansion method. The inter quark potential is modified Cornell potential. The equation of state (EoS) is evaluated for a homogeneous system. The behaviour is studied by varying the temperature as well as the number of Charm Quarks. The results clearly show signs of phase transition from Hadrons to Quark-Gluon Plasma (QGP).
Coulomb-Gauge Gluon Propagator and the Gribov Formula
Burgio, G.; Quandt, M.; Reinhardt, H.
2009-01-23
We analyze the lattice SU(2) Yang-Mills theory in the Coulomb gauge. We show that the static gluon propagator is multiplicative renormalizable and takes the simple form D(|p-vector|){sup -1}={radical}(|p-vector|{sup 2}+M{sup 4}/|p-vector|{sup 2}), proposed by Gribov through heuristic arguments many years ago. We find M=0.88(1) GeV{approx_equal}2{radical}({sigma})
RHIC AND THE PURSUIT OF THE QUARK-GLUON PLASMA.
MITCHELL,J.T.
2001-07-25
There is a fugitive on the loose. Its name is Quark-Gluon Plasma, alias the QGP. The QGP is a known informant with knowledge about the fundamental building blocks of nature that we wish to extract. This briefing will outline the status of the pursuit of the elusive QGP. We will cover what makes the QGP tick, its modus operandi, details on how we plan to hunt the fugitive down, and our level of success thus far.
Tests of QCD at HERA: determination of the gluon density
Repond, J.
1996-12-31
An overview is given of the various methods available to the colliding beam experiments at HERA to determine the gluon density of the proton. The article includes a description of fits to the structure function F{sub 2}, of studies of dijet and open charm production in deep inelastic scattering, of elastic and inelastic {psi} photoproduction, and of inclusive diffractive scattering. 13 refs., 8 figs.
Quark Gluon Plasma: Surprises from strongly coupled QCD matter
NASA Astrophysics Data System (ADS)
Jacak, Barbara
2017-01-01
Quantum Chromodynamics has long predicted a transition from normal hadronic matter to a phase where the quarks and gluons are no longer bound together and can move freely. Quark gluon plasma is now produced regularly in collisions of heavy nuclei at very high energy at both the Relativistic Heavy Ion Collider (RHIC) in the U.S. and at the LHC in Europe. Quark gluon plasma exhibits remarkable properties. Its vanishingly small shear viscosity to entropy density ratio means that it flows essentially without internal friction, making it one of the most ``perfect'' liquids known. It is also very opaque to transiting particles including heavy charm quarks, though the exact mechanism for this is not yet understood. Recent data suggest that even very small colliding systems may produce a droplet of plasma. The similarities to strongly coupled or correlated systems in ultra-cold atoms and condensed matter are striking, and have inspired novel theoretical descriptions growing out of string theory. It remains a mystery how this plasma emerges from cold, dense gluonic matter deep inside nuclei. I will discuss how a future electron-ion collider can help address this question.
Two-gluon and trigluon glueballs from dynamical holography QCD
NASA Astrophysics Data System (ADS)
Chen, Yi-dian; Huang, Mei
2016-12-01
We study the scalar, vector and tensor two-gluon and trigluon glueball spectra in the framework of the 5-dimension dynamical holographic QCD model, where the metric structure is deformed self-consistently by the dilaton field. For comparison, the glueball spectra are also calculated in the hard-wall and soft-wall holographic QCD models. In order to distinguish glueballs with even and odd parities, we introduce a positive and negative coupling between the dilaton field and glueballs, and for higher spin glueballs, we introduce a deformed 5-dimension mass. With this set-up, there is only one free parameter from the quadratic dilaton profile in the dynamical holographic QCD model, which is fixed by the scalar glueball spectra. It is found that the two-gluon glueball spectra produced in the dynamical holographic QCD model are in good agreement with lattice data. Among six trigluon glueballs, the produced masses for 1±- and 2-- are in good agreement with lattice data, and the produced masses for 0--, 0+- and 2+- are around 1.5 GeV lighter than lattice results. This result might indicate that the three trigluon glueballs of 0--, 0+- and 2+- are dominated by the three-gluon condensate contribution. Supported by the NSFC (11175251, 11621131001), DFG and NSFC (CRC 110), CAS Key Project KJCX2-EW-N01, K.C.Wong Education Foundation, and Youth Innovation Promotion Association of CAS
NASA Astrophysics Data System (ADS)
Alombert-Goget, Guillaume; Trichard, Florian; Li, Hui; Pezzani, Cyril; Silvestre, Maud; Barthalay, Nicolas; Motto-Ros, Vincent; Lebbou, Kheirreddine
2017-03-01
The titanium distributions in Ti-doped sapphires grown by Czochralski and Kyropoulos techniques were evaluated using Laser-Induced Breakdown Spectroscopy (LIBS) and luminescence characterizations. Distinctly different radial profiles of Ti4+ distribution were observed in the as grown Ti: Al2O3 crystals. The Ti4+ distribution in the crystal grown by Kyropoulos technique was analyzed as a function of the specific of the growth technique, the conclusion is significant for Ti: sapphire on laser application. Kyropoulos technique presents an advantage to reduce the proportion of Ti4+ in Ti: sapphire comparing to Czochralski technique.
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.
NASA Astrophysics Data System (ADS)
Mackler, D. A.; Pollock, C. J.; Jahn, J.; Mukherjee, J.
2011-12-01
Charge exchange between ring current ions spiraling into the upper atmosphere and terrestrial neutral constituents produces a non-isotropic distribution of escaping Energetic Neutral Atoms (ENA). These ENA's are no longer tied to the magnetic field, and can therefore be observed remotely from orbiting platforms. Particularly of interest is Low Altitude Emissions (LAE) of ENA's. These ENA emissions occur near the oxygen exobase and constitute the brightest ENA signatures during geomagnetic storms. In this study we build on previous work described in Pollock et al. [2009] in which IMAGE/MENA data was used to compute the pitch angle distribution of ENA's observed in the 29 October 2003 storm. The algorithms used in Pollock et al. [2009] are used to compute the pitch angle distribution for 80 identified storms at different phases of the solar cycle. The pitch angles are a function of invariant latitude, magnetic local time, and universal time. This allows them to be used to characterize the velocity-space distribution of ENA's emanating from the source point as well as the configuration-space distribution of ENA fluxes from a point in the upper atmosphere.
General Exact Solutions for the Full Gluon Propagator in QCD with the Mass Gap
NASA Astrophysics Data System (ADS)
Gogokhia, V.; Barnaföldi, G. G.
We have explicitly shown that Quantum Chromodynamics is a color gauge invariant theory with non-zero mass gap, which has been defined as the value of the regularized full gluon self-energy at a finite scale point. The mass gap itself is mainly generated by the nonlinear interaction of massless gluon modes. All this allows one to establish the structure of the full gluon propagator in the explicit presence of the mass gap. In this case, the two independent general types of formal solutions for the full gluon propagator as a function of the regularized mass gap have been found: (i) The nonlinear iteration solution at which the gluons remain massless is explicitly present. (ii) Existence of the solution with an effective gluon mass is also demonstrated.
Effects of jet quenching on the hydrodynamical evolution of quark-gluon plasma.
Chaudhuri, A K; Heinz, Ulrich
2006-08-11
We study the effects of jet quenching on the hydrodynamical evolution of the quark-gluon plasma (QGP) fluid created in a heavy-ion collision. In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium, leading to suppressed production of high-pT hadrons. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. For partons moving at supersonic speed, vp>cs, and sufficiently large energy loss, a shock wave forms leading to conical flow. The PHENIX Collaboration recently suggested that observed structures in the azimuthal angle distribution might be caused by conical flow. We show here that, for phenomenologically acceptable values of parton energy loss, conical flow effects are too weak to explain these structures.
Observation of tree-level B decays with ss production from gluon radiation.
Aubert, B; Bona, M; Boutigny, D; Karyotakis, Y; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lopes Pegna, D; Lynch, G; Mir, L M; Orimoto, T J; Ronan, M T; Tackmann, K; Wenzel, W A; Del Amo Sanchez, P; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Schroeder, T; Steinke, M; Walker, D; Asgeirsson, D J; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Khan, A; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Liu, F; Long, O; Shen, B C; Zhang, L; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Williams, D C; Wilson, M G; Winstrom, L O; Chen, E; Cheng, C H; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Gabareen, A M; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Brandt, T; Klose, V; Kobel, M J; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Lombardo, V; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Santoro, V; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Dauncey, P D; Flack, R L; Nash, J A; Nikolich, M B; Panduro Vazquez, W; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Béquilleux, J; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; George, K A; Di Lodovico, F; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Koeneke, K; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Zheng, Y; McLachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Fabozzi, F; Lista, L; Monorchio, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; Losecco, J M; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gagliardi, N; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; Leruste, Ph; Malclès, J; Ocariz, J; Perez, A; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cenci, R; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Biesiada, J; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Baracchini, E; Bellini, F; Cavoto, G; D'Orazio, A; Del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Castelli, G; Franek, B; Olaiya, E O; Ricciardi, S; Roethel, W; Wilson, F F; Aleksan, R; Emery, S; Escalier, M; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Hryn'ova, T; Innes, W R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Wagner, A P; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Dasu, S; Flood, K T; Hollar, J J; Kutter, P E; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Neal, H
2008-05-02
We report on our search for decays proceeding via a tree-level b-->c quark transition in which a gluon radiates into an ss[over ] pair. We present observations of the decays B;{-}-->D_{s};{+}K;{-}pi;{-} and B[over ];{0}-->D_{s};{+}K_{S};{0}pi;{-} and evidence for B;{-}-->D_{s};{+}K;{-}K;{-} and set upper limits on the branching fractions for B[over ];{0}-->D_{s};{+}K_{S};{0}pi;{-} and B;{-}-->D_{s};{+}K;{-}K;{-} using 383x10;{6} Upsilon(4S)-->BB[over ] events collected by the BABAR detector at SLAC. We present evidence that the invariant mass distributions of D_{s};{+}K;{-} pairs from B;{-}-->D_{s};{+}K;{-}pi;{-} decays are inconsistent with the phase-space model, suggesting the presence of charm resonances lying below the D_{s};{+}K;{-} threshold.
Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon
Brodsky, S.J.; Gardner, S.
2006-08-23
The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.
Wallace, A.; Romney, E.M.; Kinnear, J.
1982-07-01
Baseline measurements were made of mineral composition of alfalfa (Medicago sativa L.) and sugar beets (Beta vulgaris L.) from one field each in the Imperial Valley of California. The fields are in a geothermal area being developed for energy production, and the purpose of the investigation was to ascertain variablility within a relatively large number of samples from a common area, so that subsequent samplings could be made to satisfactorily detect whether there were changes resulting from the geothermal activity. Means, standard deviations, frequency distribution, correlations, cluster trees, and other statistics were examined for over 20 elements at each site.Most elements were normally distributed, but there was three- to fourfold range in the concentration for each.
NASA Astrophysics Data System (ADS)
Wongpratat, Unchista; Maensiri, Santi; Swatsitang, Ekaphan
2016-09-01
Effect of cations distribution upon EXAFS analysis on magnetic properties of Co1-xNixFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0) nanoparticles prepared by the hydrothermal method in aloe vera extract solution were studied. XRD analysis confirmed a pure phase of cubic spinel ferrite of all samples. Changes in lattice parameter and particle size depended on the Ni content with partial substitution and site distributions of Co2+, Ni2+ ions of different ionic radii at both tetrahedral and octahedral sites in the crystal structure. Particle sizes of samples estimated by TEM images were found to be in the range of 10.87-62.50 nm. The VSM results at room temperature indicated the ferrimagnetic behavior of all samples. Superparamagnetic behavior was observed in NiFe2O4 sample. The coercivity (Hc) and remanance (Mr) values were related to the particle sizes of samples. The saturation magnetization (Ms) was increased by a factor of 1.4 to a value of 57.57 emu/g, whereas the coercivity (Hc) was decreased by a factor of 20 to a value of 63.15 Oe for a sample with x = 0.75. In addition to the cations distribution, the increase of aspect ratio (surface to volume ratio) due to the decrease of particle size could significantly affect the magnetic properties of the materials.
How perfect can a gluon plasma be in perturbative QCD?
Chen, Jiunn-Wei; Deng Jian; Dong Hui; Wang Qun
2011-02-01
The shear viscosity to entropy density ratio, {eta}/s, characterizes how perfect a fluid is. We calculate the leading order {eta}/s of a gluon plasma in perturbation using the kinetic theory. The leading order contribution only involves the elastic gg{r_reversible}gg (22) process and the inelastic gg{r_reversible}ggg (23) process. The hard-thermal-loop (HTL) treatment is used for the 22 matrix element, while the exact matrix element in vacuum is supplemented by the gluon Debye mass insertion for the 23 process. Also, the asymptotic mass is used for the external gluons in the kinetic theory. The errors from not implementing HTL and the Landau-Pomeranchuk-Migdal effect in the 23 process, and from the uncalculated higher order corrections, are estimated. Our result smoothly connects the two different approximations used by Arnold, Moore, and Yaffe (AMY) and Xu and Greiner (XG). At small {alpha}{sub s} ({alpha}{sub s}<<1), our result is closer to AMY's collinear result while at larger {alpha}{sub s} the finite angle noncollinear configurations become more important and our result is closer to XG's soft bremsstrahlung result. In the region where perturbation is reliable ({alpha}{sub s} < or approx. 0.1), we find no indication that the proposed perfect fluid limit {eta}/s{approx_equal}1/(4{pi}) can be achieved by perturbative QCD alone. Whether this can be achieve for {alpha}{sub s} > or approx. 0.1 is still an open question.
Heavy quarks, gluons and the confinement potential in Coulomb gauge
Popovici, Carina; Watson, Peter; Reinhardt, Hugo
2011-05-23
We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.
Interactions of quarks and gluons with nuclei at intermediate energies
Mueller, A.H.
1994-04-01
Some processes involving the interaction of medium energy quarks and gluons with nuclear matter are described. Possible mechanisms for the A-dependence of the energy loss of leading protons produced in proton-nucleus collisions are given, and an experiment which may help to distinguish these mechanisms is described. A possible color transparency experiment at CEBAF is described. Experiments to measure energy loss of quarks in nuclear matter and the formation time of hadrons are discussed along with the possibilities of measuring {sigma}{sub J}/{psi} and {sigma}{sub {psi}{prime}} at CEBAF.
Attractive Casimir effect in an infrared modified gluon bag model
Oxman, L.E.; Amaral, R.L.P.G.
2005-12-15
In this work, we are motivated by previous attempts to derive the vacuum contribution to the bag energy in terms of familiar Casimir energy calculations for spherical geometries. A simple infrared modified model is introduced which allows studying the effects of the analytic structure as well as the geometry in a clear manner. In this context, we show that if a class of infrared vanishing effective gluon propagators is considered, then the renormalized vacuum energy for a spherical bag is attractive, as required by the bag model to adjust hadron spectroscopy.
Quark-gluon plasma and topological quantum field theory
NASA Astrophysics Data System (ADS)
Luo, M. J.
2017-03-01
Based on an analogy with topologically ordered new state of matter in condensed matter systems, we propose a low energy effective field theory for a parity conserving liquid-like quark-gluon plasma (QGP) around critical temperature in quantum chromodynamics (QCD) system. It shows that below a QCD gap which is expected several times of the critical temperature, the QGP behaves like topological fluid. Many exotic phenomena of QGP near the critical temperature discovered at Relativistic Heavy Ion Collision (RHIC) are more readily understood by the suggestion that QGP is a topologically ordered state.
Quarks and gluons in the nucleon: Proceedings. Volume 6
1997-12-31
The purpose of the symposium was to discuss the quark and gluon structure of the nucleon as probed experimentally by hard processes with lepton and hadron beams and studied theoretically by perturbative QCD, lattice QCD and effective models on the one hand and to stimulate research activities in the fields related to RHIC and RHIC-SPIN projects on the other hand. There were 18 talks and 2 discussion sessions. About 50, including 5 from abroad participated in the symposium. An excellent summary in the form of 5 most important transparencies and a one-page explanation is included for each of the invited talks.
Search for the Quark Gluon Plasma: A Status Report
NASA Astrophysics Data System (ADS)
Nagle, J. L.
2006-07-01
This document is the proceedings from an overview talk on the search for the Quark Gluon Plasma (QGP) given at the Particles and Nuclei International Conference (PANIC) in Santa Fe, New Mexico in October 2005. After five years of successful data taking at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, there is much to report in this field of physics. In this short review, we present a bulleted list of experimental discoveries and conclusions to date on the matter formed in these highest energy nuclear reactions.
Universal behavior of gluon and ghost propagators in the infrared
NASA Astrophysics Data System (ADS)
Siringo, Fabio
2017-03-01
A universal behavior is predicted for ghost and gluon propagators in the infrared. The universal behavior is shown to be a signature of a one-loop approximation and emerges naturally by the massive expansion that predicts universal analytical functions for the inverse dressing functions that do not depend on any parameter or color number. By a scaling of units and by adding an integration constant, all lattice data, for different color numbers (and even quark content for the ghosts), collapse on the same universal curves predicted by the massive expansion.
Threshold region for Higgs boson production in gluon fusion.
Bonvini, Marco; Forte, Stefano; Ridolfi, Giovanni
2012-09-07
We provide a quantitative determination of the effective partonic kinematics for Higgs boson production in gluon fusion in terms of the collider energy at the LHC. We use the result to assess, as a function of the Higgs boson mass, whether the large m(t) approximation is adequate and Sudakov resummation advantageous. We argue that our results hold to all perturbative orders. Based on our results, we conclude that the full inclusion of finite top mass corrections is likely to be important for accurate phenomenology for a light Higgs boson with m(H)~125 GeV at the LHC with √s=14 TeV.
Eikonal gluon bremsstrahlung at finite Nc beyond two loops
NASA Astrophysics Data System (ADS)
Delenda, Yazid; Khelifa-Kerfa, Kamel
2016-03-01
We present a general formalism for computing the matrix-element squared for the emission of soft energy-ordered gluons beyond two loops in QCD perturbation theory at finite Nc. Our formalism is valid in the eikonal approximation. A Mathematica program has been developed for the automated calculation of all real/virtual eikonal squared amplitudes needed at a given loop order. For the purpose of illustration, we show the explicit forms of the eikonal squared amplitudes up to the fifth-loop order. In the large-Nc limit, our results coincide with those previously reported in literature.
NASA Astrophysics Data System (ADS)
Adolph, C.; Alekseev, M. G.; Alexakhin, V. Yu.; Alexandrov, Yu.; Alexeev, G. D.; Amoroso, A.; Antonov, A. A.; Austregesilo, A.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bertini, R.; Bettinelli, M.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Das, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M., Jr.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Goertz, S.; Grabmüller, S.; Grasso, A.; Grube, B.; Gushterski, R.; Guskov, A.; Guthörl, T.; Haas, F.; von Harrach, D.; Heinsius, F. H.; Herrmann, F.; Heß, C.; Hinterberger, F.; Horikawa, N.; Höppner, Ch.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, O.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koblitz, S.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Korzenev, A.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kroumchtein, Z. V.; Kunne, F.; Kurek, K.; Lauser, L.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Liska, T.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Morreale, A.; Mutter, A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Nowak, W.-D.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Padee, A.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Perevalova, E.; Pesaro, G.; Peshekhonov, D. V.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Rajotte, J.-F.; Ramos, S.; Rapatsky, V.; Reicherz, G.; Rocco, E.; Rondio, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sapozhnikov, M. G.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, A.; Schmidt, K.; Schmitt, L.; Schmïden, H.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sissakian, A. N.; Slunecka, M.; Smirnov, G. I.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Sznajder, P.; Takekawa, S.; Ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Tkatchev, L. G.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vlassov, N. V.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wiślicki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zhuravlev, N.; Zvyagin, A.
2013-03-01
The gluon polarization in the nucleon was measured using open charm production by scattering 160GeV/c polarized muons off longitudinally polarized protons or deuterons. The data were taken by the COMPASS Collaboration between 2002 and 2007. A detailed account is given of the analysis method that includes the application of neural networks. Several decay channels of D0 mesons are investigated. Longitudinal spin asymmetries of the D meson production cross sections are extracted in bins of D0 transverse momentum and energy. At leading order QCD accuracy, the average gluon polarization is determined as ⟨Δg/g⟩LO=-0.06±0.21(stat.)±0.08(syst.) at the scale ⟨μ2⟩≈13(GeV/c)2 and an average gluon momentum fraction ⟨x⟩≈0.11. The average gluon polarization is also obtained at next-to-leading order QCD accuracy as ⟨Δg/g⟩ NLO=-0.13±0.15(stat.)±0.15(syst.) at the scale ⟨μ2⟩≈13(GeV/c)2 and ⟨x⟩≈0.20.
NASA Astrophysics Data System (ADS)
Campanario, Francisco; Kubocz, Michael
2013-09-01
Higgs production in association with three jets via gluon fusion is an important channel for the measurement of the CP properties of the Higgs particle at the LHC. In this paper, we go beyond the heavy top effective theory approximation and include at LO the full mass dependence of the top- and bottom-quark contributions. We consider the dominant subchannel gg→Hggg which involves the manipulation of massive rank-5 hexagon integrals. Furthermore, we present results for several differential distributions and show deviations from the effective theory as large as 100% at high pT for light Higgs masses.
NASA Astrophysics Data System (ADS)
Gervino, Gianpiero; Lavagno, Andrea; Pigato, Daniele
2012-06-01
We investigate the relativistic equation of state of hadronic matter and quark-gluon plasma at finite temperature and baryon density in the framework of the non-extensive statistical mechanics, characterized by power-law quantum distributions. We impose the Gibbs conditions on the global conservation of baryon number, electric charge and strangeness number. For the hadronic phase, we study an extended relativistic mean-field theoretical model with the inclusion of strange particles (hyperons and mesons). For the quark sector, we employ an extended MIT-Bag model. In this context we focus on the relevance of non-extensive effects in the presence of strange matter.
NASA Astrophysics Data System (ADS)
Gökçe, M.; Uslu, D. Koçyiǧit; Ertunç, C.; Karalı, T.
2016-03-01
The aim of this study is to compare Intensity Modulated Radiation Therapy (IMRT) plan of prostate cancer patients with different dose verification systems in dosimetric aspects and to compare these systems with each other in terms of reliability, applicability and application time. Dosimetric control processes of IMRT plan of three prostate cancer patients were carried out using thermoluminescent dosimeter (TLD), ion chamber (IC) and 2D Array detector systems. The difference between the dose values obtained from the dosimetric systems and treatment planning system (TPS) were found to be about % 5. For the measured (TLD) and calculated (TPS) doses %3 percentage differences were obtained for the points close to center while percentage differences increased at the field edges. It was found that TLD and IC measurements will increase the precision and reliability of the results of 2D Array.
Rayner, Keith; Juhasz, Barbara J; Brown, Sarah J
2007-02-01
Two experiments tested predictions derived from serial lexical processing and parallel distributed models of eye movement control in reading. The boundary paradigm (K. Rayner, 1975) was used, and the boundary location was set either at the end of word n - 1 (the word just to the left of the target word) or at the end of word n - 2. Serial lexical processing models predict that there should be preview benefit only when the boundary is set at word n - 1 (when the target word will be the next word fixated) and no preview benefit when the boundary is set at word n - 2. Parallel lexical models, on the other hand, predict that there should be some preview benefit in both situations. Consistent with the predictions of the serial lexical processing models, there was no preview benefit for a target word when the boundary was set at the end of word n - 2. Furthermore, there was no evidence of parafoveal-on-foveal effects.
Singh, Warsha; Örnólfsdóttir, Erla B; Stefansson, Gunnar
2014-01-01
An approach is developed to estimate size of Iceland scallop shells from AUV photos. A small-scale camera based AUV survey of Iceland scallops was conducted at a defined site off West Iceland. Prior to height estimation of the identified shells, the distortions introduced by the vehicle orientation and the camera lens were corrected. The average AUV pitch and roll was 1.3 and 2.3 deg that resulted in <2% error in ground distance rendering these effects negligible. A quadratic polynomial model was identified for lens distortion correction. This model successfully predicted a theoretical grid from a frame photographed underwater, representing the inherent lens distortion. The predicted shell heights were scaled for the distance from the bottom at which the photos were taken. This approach was validated by height estimation of scallops of known sizes. An underestimation of approximately 0.5 cm was seen, which could be attributed to pixel error, where each pixel represented 0.24 x 0.27 cm. After correcting for this difference the estimated heights ranged from 3.8-9.3 cm. A comparison of the height-distribution from a small-scale dredge survey carried out in the vicinity showed non-overlapping peaks in size distribution, with scallops of a broader size range visible in the AUV survey. Further investigations are necessary to evaluate any underlying bias and to validate how representative these surveys are of the true population. The low resolution images made identification of smaller scallops difficult. Overall, the observations of very few small scallops in both surveys could be attributed to low recruitment levels in the recent years due to the known scallop parasite outbreak in the region.
Singh, Warsha; Örnólfsdóttir, Erla B.; Stefansson, Gunnar
2014-01-01
An approach is developed to estimate size of Iceland scallop shells from AUV photos. A small-scale camera based AUV survey of Iceland scallops was conducted at a defined site off West Iceland. Prior to height estimation of the identified shells, the distortions introduced by the vehicle orientation and the camera lens were corrected. The average AUV pitch and roll was and deg that resulted in error in ground distance rendering these effects negligible. A quadratic polynomial model was identified for lens distortion correction. This model successfully predicted a theoretical grid from a frame photographed underwater, representing the inherent lens distortion. The predicted shell heights were scaled for the distance from the bottom at which the photos were taken. This approach was validated by height estimation of scallops of known sizes. An underestimation of approximately cm was seen, which could be attributed to pixel error, where each pixel represented cm. After correcting for this difference the estimated heights ranged from cm. A comparison of the height-distribution from a small-scale dredge survey carried out in the vicinity showed non-overlapping peaks in size distribution, with scallops of a broader size range visible in the AUV survey. Further investigations are necessary to evaluate any underlying bias and to validate how representative these surveys are of the true population. The low resolution images made identification of smaller scallops difficult. Overall, the observations of very few small scallops in both surveys could be attributed to low recruitment levels in the recent years due to the known scallop parasite outbreak in the region. PMID:25303243
Xu Zhe; Greiner, Carsten
2007-08-15
To describe momentum isotropization of gluon matter produced in ultrarelativistic heavy-ion collisions, the transport rate of gluon drift and the transport collision rates of elastic (gg{r_reversible}gg) as well as inelastic (gg{r_reversible}ggg) perturbative quantum chromodynamics- (pQCD) scattering processes are introduced and calculated within the kinetic parton cascade Boltzmann approach of multiparton scatterings (BAMPS), which simulates the space-time evolution of partons. We define isotropization as the development of an anisotropic system as it reaches isotropy. The inverse of the introduced total transport rate gives the correct time scale of the momentum isotropization. The contributions of the various scattering processes to the momentum isotropization can be separated into the transport collision rates. In contrast to the transport cross section, the transport collision rate has an indirect but correctly implemented relationship with the collision-angle distribution. Based on the calculated transport collision rates from BAMPS for central Au+Au collisions at Relativistic Heavy Ion Collider energies, we show that pQCD gg{r_reversible}ggg bremsstrahlung processes isotropize the momentum five times more efficiently than elastic scatterings. The large efficiency of the bremsstrahlung stems mainly from its large momentum deflection. Due to kinematics, 2{yields}N (N>2) production processes allow more particles to become isotropic in momentum space and thus kinetically equilibrate more quickly than their back reactions or elastic scatterings. We also show that the relaxation time in the relaxation time approximation, which is often used, is strongly momentum dependent and thus cannot serve as a global quantity that describes kinetic equilibration.
Pre-equilibrium dilepton production from an anisotropic quark-gluon plasma
Martinez, Mauricio; Strickland, Michael
2008-09-15
We calculate leading-order dilepton yields from a quark-gluon plasma that has a time-dependent anisotropy in momentum space. Such anisotropies can arise during the earliest stages of quark-gluon plasma evolution due to the rapid longitudinal expansion of the created matter. Two phenomenological models for the proper-time dependence of the parton hard momentum scale, p{sub hard}, and the plasma anisotropy parameter, {xi}, are constructed that describe the transition of the plasma from its initial nonequilibrium state to an isotropic thermalized state. The first model constructed interpolates between 1+1 dimensional free streaming at early times and 1+1 dimensional ideal hydrodynamical expansion at late times. In the second model we include the effect of collisional broadening of the parton distribution functions in the early-time pre-equilibrium stage of plasma evolution. We find for both cases that for fixed initial conditions high-energy dilepton production is enhanced by pre-equilibrium emission. When the models are constrained to fixed final pion multiplicity the dependence of the resulting spectra on the assumed plasma isotropization time is reduced. Using our most realistic collisionally broadened model we find that high-transverse-momentum dilepton production would be enhanced by at most 40% at the Relativistic Heavy Ion Collider and 50% at the CERN Large Hadron Collider if one assumes an isotropization/thermalization time of 2 fm/c. Given sufficiently precise experimental data this enhancement could be used to determine the plasma isotropization time experimentally.
Small shear viscosity in the semiquark gluon plasma
Hidaka, Yoshimasa; Pisarski, Robert D.
2010-04-01
At nonzero temperature in QCD, about the deconfining phase transition there is a semiquark gluon plasma (semi-QGP), where the expectation value of the (renormalized) Polyakov loop is less than one. This can be modeled by a semiclassical expansion about a constant field for the vector potential, A{sub 0}, which is diagonal in color. We compute the shear viscosity in the semi-QGP by using the Boltzmann equation in the presence of this background field. To leading, logarithmic order in weak coupling, the dominant diagrams are given by the usual scattering processes of 2{yields}2 particles. For simplicity we also assume that both the number of colors and flavors are large. Near the critical temperature T{sub c}, where the expectation value of the Polyakov loop is small, the overall density of colored fields decreases according to their color representation, with the density of quarks vanishes linearly with the loop, and that of gluons, quadratically. This decrease in the overall density dominates changes in the transport cross section. As a result, relative to that in the perturbative QGP, near T{sub c} the shear viscosity in the semi-QGP is suppressed by two powers of the Polyakov loop. In a semiclassical expansion, the suppression of colored fields depends only upon which color representation they lie in, and not upon their mass. That light and heavy quarks are suppressed in a common manner may help to explain the behavior of charm quarks at RHIC.
Quark-gluon vertex: A perturbation theory primer and beyond
NASA Astrophysics Data System (ADS)
Bermudez, R.; Albino, L.; Gutiérrez-Guerrero, L. X.; Tejeda-Yeomans, M. E.; Bashir, A.
2017-02-01
There has been growing evidence that the infrared enhancement of the form factors defining the full quark-gluon vertex plays an important role in realizing a dynamical breakdown of chiral symmetry in quantum chromodynamics, leading to the observed spectrum and properties of hadrons. Both the lattice and the Schwinger-Dyson communities have begun to calculate these form factors in various kinematical regimes of momenta involved. A natural consistency check for these studies is that they should match onto the perturbative predictions in the ultraviolet, where nonperturbative effects mellow down. In this article, we carry out a numerical analysis of the one-loop result for all the form factors of the quark-gluon vertex. Interestingly, even the one-loop results qualitatively encode most of the infrared enhancement features expected of their nonperturbative counter parts. We analyze various kinematical configurations of momenta: symmetric, on shell, and asymptotic. The on-shell limit enables us to compute anomalous chromomagnetic moment of quarks. The asymptotic results have implications for the multiplicative renormalizability of the quark propagator and its connection with the Landau-Khalatnikov-Fradkin transformations, allowing us to analyze and compare various Ansätze proposed so far.
Quark mean field model with pion and gluon corrections
NASA Astrophysics Data System (ADS)
Xing, Xueyong; Hu, Jinniu; Shen, Hong
2016-10-01
The properties of nuclear matter and finite nuclei are studied within the quark mean field (QMF) model by taking the effects of pions and gluons into account at the quark level. The nucleon is described as the combination of three constituent quarks confined by a harmonic oscillator potential. To satisfy the spirit of QCD theory, the contributions of pions and gluons on the nucleon structure are treated in second-order perturbation theory. In a nuclear many-body system, nucleons interact with each other by exchanging mesons between quarks. With different constituent quark mass, mq, we determine three parameter sets for the coupling constants between mesons and quarks, named QMF-NK1, QMF-NK2, and QMF-NK3, by fitting the ground-state properties of several closed-shell nuclei. It is found that all of the three parameter sets can give a satisfactory description of properties of nuclear matter and finite nuclei, moreover they also predict a larger neutron star mass around 2.3 M⊙ without hyperon degrees of freedom.
Understanding the Quark-gluon Plasma via String Theory
NASA Astrophysics Data System (ADS)
Liu, Hong
2007-10-01
Collisions of high-energy gold nuclei at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory create exploding droplets of quark-gluon plasma, the stuff which filled the universe microseconds after the Big Bang. The quark- gluon plasma at RHIC exhibits many surprising properties: it is close to an ideal liquid and it strongly attenuates the high energy quarks trying to plow through it. So far calculations in QCD have not been able to explain these properties satisfactorily, but interesting insight has been gained by using techniques from string theory. In the last ten years string theory has revealed a surprising and deep connection between quantum gravity and non-Abelian gauge theories similar to QCD. Such a connection enables one to answer difficult questions in some strongly coupled gauge theories by simple calculations of classical gravity. I will discuss some examples where these string theory techniques have been used to shed light on existing data from RHIC and to make one prediction that can be tested by experiments in the near future.
New signals of quark-gluon-hadron mixed phase formation
NASA Astrophysics Data System (ADS)
Bugaev, K. A.; Sagun, V. V.; Ivanytskyi, A. I.; Oliinychenko, D. R.; Ilgenfritz, E.-M.; Nikonov, E. G.; Taranenko, A. V.; Zinovjev, G. M.
2016-08-01
Here we present several remarkable irregularities at chemical freeze-out which are found using an advanced version of the hadron resonance gas model. The most prominent of them are the sharp peak of the trace anomaly existing at chemical freeze-out at the center-of-mass energy 4.9 GeV and two sets of highly correlated quasi-plateaus in the collision energy dependence of the entropy per baryon, total pion number per baryon, and thermal pion number per baryon which we found at the center-of-mass energies 3.8-4.9 GeV and 7.6-10 GeV. The low-energy set of quasi-plateaus was predicted a long time ago. On the basis of the generalized shock-adiabat model we demonstrate that the low-energy correlated quasi-plateaus give evidence for the anomalous thermodynamic properties inside the quark-gluon-hadron mixed phase. It is also shown that the trace anomaly sharp peak at chemical freeze-out corresponds to the trace anomaly peak at the boundary between the mixed phase and quark gluon plasma. We argue that the high-energy correlated quasi-plateaus may correspond to a second phase transition and discuss its possible origin and location. Besides we suggest two new observables which may serve as clear signals of these phase transformations.
Quark and gluon form factors to four-loop order in QCD: The Nf3 contributions
NASA Astrophysics Data System (ADS)
von Manteuffel, Andreas; Schabinger, Robert M.
2017-02-01
We calculate the four-loop massless QCD corrections with three closed quark lines to quark and gluon form factors. We apply a novel integration by parts algorithm based on modular arithmetic and compute all relevant master integrals for arbitrary values of the space-time dimension. This is the first calculation of a gluon form factor at this perturbative order in QCD.
Non-transversality of the gluon self-energy and the DDT analysis
NASA Astrophysics Data System (ADS)
Konetschny, W.
1982-12-01
It is found that the one-loop corrections to the propagator induced by the non-transversality of the gluon self energy in the planar gauge are not kinematically suppressed in the leading logarithm approximation. As a consequence the multiplicative renormalization of the bare gluon propagator assumed by Dokshitzer, Dyakonov and Troyan is lost.
Introduction to quantum chromo transport theory for quark-gluon plasmas
Gyulassy, M.; Elze, H.Th.; Iwazaki, A.; Vasak, D.
1986-08-01
Upcoming heavy ion experiments at the AGS and SPS are aimed at producing and diagnosing a primordial form of matter, the quark-gluon plasma. In these lectures some recent developments on formulating a quantum transport theory for quark-gluon plasmas are introduced. 46 refs.
Analytic Form of the Two-Loop Planar Five-Gluon All-Plus-Helicity Amplitude in QCD.
Gehrmann, T; Henn, J M; Lo Presti, N A
2016-02-12
Virtual two-loop corrections to scattering amplitudes are a key ingredient to precision physics at collider experiments. We compute the full set of planar master integrals relevant to five-point functions in massless QCD, and use these to derive an analytical expression for the two-loop five-gluon all-plus-helicity amplitude. After subtracting terms that are related to the universal infrared and ultraviolet pole structure, we obtain a remarkably simple and compact finite remainder function, consisting only of dilogarithms.
Cacciari, Matteo; Mangano, Michelangelo L; Nason, Paolo
We discuss production of charm and bottom quarks at forward rapidity in pp collisions at the LHC, updating the QCD predictions for the run at [Formula: see text] TeV. We show that, while the absolute rates suffer from large theoretical systematics, dominated by scale uncertainties, the increase relative to the rates precisely measured at 7 TeV can be predicted with an accuracy of a few percent, sufficient to highlight the sensitivity to the gluon distribution function.
NASA Astrophysics Data System (ADS)
Wolin, Scott Justin
The PHENIX experiment is one of two detectors located at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, NY. Understanding the spin structure of the proton is a central goal at RHIC, the only polarized proton-on-proton collider in existence. The PHENIX spin program has two primary objectives. The first is to improve the constraints on the polarized parton distributions of the anti-u and anti-d quarks within the proton. The second objective is to improve the constraint on the gluon spin contribution to the proton spin, DeltaG. The focus of this thesis is the second objective. PHENIX experiment has been successful at providing the first meaningful constraints on DeltaG, along with STAR, the other detector located at RHIC. These constraints have, in fact, eliminated the extreme scenarios for gluon polarization through measurements of the double spin asymmetry, ALL, between the cross section of like and unlike sign helicity pp interactions. ALL measurements can be performed with a variety of final states at PHENIX. Until 2009, these final states were only measured for pseudo-rapidities of |eta| < 0.35. This range of eta is referred to as mid-rapidity. These mid-rapidity measurements, like the polarized DIS measurements, suffer from a limited kinematic reach. Final states containing a measured particle with pT [special character omitted] 1 GeV/c are considered to have occurred in the hard scattering domain where the pp interaction is well approximated as an interaction of a quark or gluon in one proton and a quark or gluon in the second proton. Each of these interacting particles has a momentum fraction, x, of its parent proton's momentum. The gluon polarization is dependent on the momentum fraction and the net gluon polarization can be written as the integral of the momentum fraction dependent polarization: DeltaG = f(1,0)Delta g(x)dx. The momentum fractions of the two interacting particles give information about the final state
Zhu, Yanbei; Hioki, Akiharu; Chiba, Koichi
2013-01-01
Eighteen elements in the cotyledon, the embryonic axis, and the testa of peanut seeds were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave acid digestion, while the gravimetric standard addition with internal standard was applied for the calibration of the elemental concentrations. The detection limit and the procedure blank value for each element were low enough to ensure the precise analysis of the elements, with a relative expanded uncertainty of less than 5%. The concentrations of the elements in peanut seed samples covered 6 orders of magnitude from approximately 0.01 mg kg(-1) of Co to approximately 7000 mg kg(-1) of K. The correlation coefficient factor was around 0.98 for the elemental concentrations in peanut seeds grown in Japan and those grown in China, indicating a good correlation. Most of the elements distributed in the cotyledon in large amounts because of the cotyledon's relatively high mass fraction. By contrast, Na, Ca, Fe, Co, Ni, Cu, Ga, Sr, Cd, and Ba were apparently enriched in the testa and the relative enrichment factor (REF) values of the elements were over 4. The relative enrichment of Mo, Fe, Zn and other elements was observed in the embryonic axis samples with REF values over 2. The relative enrichment of Cd in the testa of peanut seed indicates that about 15 to 25% of the Cd intake through peanut seeds could be effectively lowered by removal of the testa (roughly 2.5 to 3.5% of the peanut seed).
NASA Astrophysics Data System (ADS)
Snyder, Douglas
For a pair of entangled signal-idler photons, one may ``lose'' the idler photon (that provides which-way information to the entangled signal photon) in many other photons with similar characteristics to the idler photon before the signal photon is detected, thereby losing the which-way information supplied to the signal photon and eliminating the entanglement. The experiment allows for a delayed choice on the idler photons (whether or not to lose the idler photon before the signal photon is detected) to determine the distribution of distant signal photons (either overall which-way or overall interference) without making correlations between signal and idler photon detections. When the idler photon is lost, it is lost in an optical microcavity filled with photons in the same mode as the idler photon. The experiment could provide the basis for a useful quantum communications device. It might be possible to use a micropost coated with a material such as Vantablack in place of the optical microcavity.
Infrared suppression of the Coulomb gauge gluon propagator in SU(3) Yang-Mills theory
NASA Astrophysics Data System (ADS)
Nakagawa, Y.
We calculate the equal-time transverse gluon propagator in Coulomb gauge QCD using a SU(3) quenched lattice gauge simulation on large lattices, up to 114 [fm4 ]. We find that the equal-time gluon propagator shows scaling violation; namely, the data for different lattice spacings do not fall on top of one curve. This problem is cured by discarding data at large momenta, which suffer from discretization errors. In the infrared region, the transverse gluon propagator is strongly suppressed and shows a turnover at about 500 [MeV]. Fitting the power law ansatz to the data at small momenta predicts the vanishing gluon propagator at zero momentum, indicating the confinement of gluons.
Quark-gluon tagging with shower deconstruction: Unearthing dark matter and Higgs couplings
NASA Astrophysics Data System (ADS)
Ferreira de Lima, Danilo; Petrov, Petar; Soper, Davison; Spannowsky, Michael
2017-02-01
The separation of quark and gluon initiated jets can be an important way to improve the sensitivity in searches for new physics or in measurements of Higgs boson properties. We present a simplified version of the shower deconstruction approach as a novel observable for quark-gluon tagging. Assuming topoclusterlike objects as input, we compare our observable with energy correlation functions and find a favorable performance for a large variety of jet definitions. We address the issue of infrared sensitivity of quark-gluon discrimination. When this approach is applied to dark matter searches in monojet final states, limitations from small signal-to-background ratios can be overcome. We also show that quark-gluon tagging is an alternative way of separating weak boson from gluon-fusion production in the process p +p →H +jet+jet+X .
Mochalski, Paweł; Unterkofler, Karl; Španěl, Patrik; Smith, David; Amann, Anton
2014-04-15
Product ion distributions for the reactions of NO(+) with 22 aldehydes involved in human physiology have been determined under the prevailing conditions of a selective reagent ionization time of flight mass spectrometry (SRI-TOF-MS) at an E/N in the flow/drift tube reactor of 130 Td. The chosen aldehydes were fourteen alkanals (the C2-C11 n-alkanals, 2-methyl propanal, 2-methyl butanal, 3-methyl butanal, and 2-ethyl hexanal), six alkenals (2-propenal, 2-methyl 2-propenal, 2-butenal, 3-methyl 2-butenal, 2-methyl 2-butenal, and 2-undecenal), benzaldehyde, and furfural. The product ion fragmentations patterns were determined for both dry air and humid air (3.5% absolute humidity) used as the matrix buffer/carrier gas in the drift tube of the SRI-TOF-MS instrument. Hydride ion transfer was seen to be a common ionization mechanism in all these aldehydes, thus generating (M-H)(+) ions. Small fractions of the adduct ion, NO(+)M, were also seen for some of the unsaturated alkenals, in particular 2-undecenal, and heterocyclic furfural for which the major reactive channel was non-dissociative charge transfer generating the M(+) parent ion. Almost all of the reactions resulted in partial fragmentation of the aldehyde molecules generating hydrocarbon ions; specifically, the alkanal reactions resulted in multiple product ions, whereas, the alkenals reactions produced only two or three product ions, dissociation of the nascent excited product ion occurring preferentially at the 2-position. The findings of this study are of particular importance for data interpretation in studies of aldehydes reactions employing SRI-TOF-MS in the NO(+) mode.
Mochalski, Paweł; Unterkofler, Karl; Španěl, Patrik; Smith, David; Amann, Anton
2014-01-01
Product ion distributions for the reactions of NO+ with 22 aldehydes involved in human physiology have been determined under the prevailing conditions of a selective reagent ionization time of flight mass spectrometry (SRI-TOF-MS) at an E/N in the flow/drift tube reactor of 130 Td. The chosen aldehydes were fourteen alkanals (the C2–C11 n-alkanals, 2-methyl propanal, 2-methyl butanal, 3-methyl butanal, and 2-ethyl hexanal), six alkenals (2-propenal, 2-methyl 2-propenal, 2-butenal, 3-methyl 2-butenal, 2-methyl 2-butenal, and 2-undecenal), benzaldehyde, and furfural. The product ion fragmentations patterns were determined for both dry air and humid air (3.5% absolute humidity) used as the matrix buffer/carrier gas in the drift tube of the SRI-TOF-MS instrument. Hydride ion transfer was seen to be a common ionization mechanism in all these aldehydes, thus generating (M−H)+ ions. Small fractions of the adduct ion, NO+M, were also seen for some of the unsaturated alkenals, in particular 2-undecenal, and heterocyclic furfural for which the major reactive channel was non-dissociative charge transfer generating the M+ parent ion. Almost all of the reactions resulted in partial fragmentation of the aldehyde molecules generating hydrocarbon ions; specifically, the alkanal reactions resulted in multiple product ions, whereas, the alkenals reactions produced only two or three product ions, dissociation of the nascent excited product ion occurring preferentially at the 2-position. The findings of this study are of particular importance for data interpretation in studies of aldehydes reactions employing SRI-TOF-MS in the NO+ mode. PMID:25844049
NASA Astrophysics Data System (ADS)
Billon, Astrid; Hénault, Jean-Marie; Quiertant, Marc; Taillade, Frédéric; Khadour, Aghiad; Martin, Renaud-Pierre; Benzarti, Karim
2015-11-01
Distributed optical fiber systems (DOFSs) are an emerging and innovative technology that allows long-range and continuous strain/temperature monitoring with a high resolution. Sensing cables are either surface-mounted or embedded into civil engineering structures to ensure long-term structural monitoring and early crack detection. However, strain profiles measured in the optical fiber (OF) may differ from the actual strain in the structure due to the shear transfer through the intermediate material layers between the OF and the host material (i.e., in the protective coating of the sensing cable and in the adhesive). Therefore, OF sensors need to be qualified to provide accurate quantitative strain measurements. This study presents a methodology for the qualification of a DOFS. This qualification is achieved through the calculation of the so-called mechanical transfer function (MTF), which relates the strain profile in the OF to the actual strain profile in the structure. It is proposed to establish a numerical modeling of the system, in which the mechanical parameters are calibrated from experiments. A specific surface-mounted sensing cable connected to an optical frequency domain reflectometry interrogator is considered as a case study. It was found that (i) tensile and pull-out tests can provide detailed information about materials and interfaces of the numerical model; (ii) the calibrated model made it possible to compute strain profiles along the OF and therefore to calculate the MTF of the system; (iii) the results proved to be consistent with experimental data collected on a cracked concrete beam during a four-point bending test. This paper is organized as follows: first, the technical background related to DOFSs and interrogators is briefly recalled, the MTF is defined and the above-mentioned methodology is presented. In the second part, the methodology is applied to a specific cable. Finally, a comparison with experimental evidence validates the proposed
NASA Astrophysics Data System (ADS)
Wang, Jin; Zhang, Cao; Katz, Joseph
2016-11-01
A PIV based method to reconstruct the volumetric pressure field by direct integration of the 3D material acceleration directions has been developed. Extending the 2D virtual-boundary omni-directional method (Omni2D, Liu & Katz, 2013), the new 3D parallel-line omni-directional method (Omni3D) integrates the material acceleration along parallel lines aligned in multiple directions. Their angles are set by a spherical virtual grid. The integration is parallelized on a Tesla K40c GPU, which reduced the computing time from three hours to one minute for a single realization. To validate its performance, this method is utilized to calculate the 3D pressure fields in isotropic turbulence and channel flow using the JHU DNS Databases (http://turbulence.pha.jhu.edu). Both integration of the DNS acceleration as well as acceleration from synthetic 3D particles are tested. Results are compared to other method, e.g. solution to the Pressure Poisson Equation (e.g. PPE, Ghaemi et al., 2012) with Bernoulli based Dirichlet boundary conditions, and the Omni2D method. The error in Omni3D prediction is uniformly low, and its sensitivity to acceleration errors is local. It agrees with the PPE/Bernoulli prediction away from the Dirichlet boundary. The Omni3D method is also applied to experimental data obtained using tomographic PIV, and results are correlated with deformation of a compliant wall. ONR.
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.
NASA Astrophysics Data System (ADS)
Kłusek-Gawenda, Mariola; Schäfer, Wolfgang; Szczurek, Antoni
2016-10-01
We discuss the two-gluon exchange contribution (formally three-loops) to elastic photon-photon scattering in the high-energy approximation. The elastic γγ → γγ amplitude is given in the impact-factor representation for all helicity configurations and finite quark masses. We discuss the importance of including the charm quark, which contribution, due to interference, can enhance the cross section considerably. We investigate the contribution to the γγ → γγ amplitude from the soft region, by studying its dependence on nonperturbative gluon mass. Helicity-flip contributions are shown to be much smaller than helicity-conserving ones. We identify region(s) of phase space where the two-gluon exchange contribution becomes important ingredient compared to box and nonperturbative VDM-Regge mechanisms considered in the literature. Consequences for the AA → AAγγ reaction are discussed. Several differential distributions are shown. A feasibility study to observe the effect of two-gluon exchange is presented. We perform a similar analysis for the pp → ppγγ reaction. Only by imposing severe cuts on Mγγ and a narrow window on photon transverse momenta the two gluon contribution becomes comparable to the box contribution but the corresponding cross section is rather small.
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.
The one loop gluon emission light cone wave function
NASA Astrophysics Data System (ADS)
Lappi, T.; Paatelainen, R.
2017-04-01
Light cone perturbation theory has become an essential tool to calculate cross sections for various small- x dilute-dense processes such as deep inelastic scattering and forward proton-proton and proton-nucleus collisions. Here we set out to do one loop calculations in an explicit helicity basis in the four dimensional helicity scheme. As a first process we calculate light cone wave function for one gluon emission to one-loop order in Hamiltonian perturbation theory on the light front. We regulate ultraviolet divergences with transverse dimensional regularization and soft divergences using a cut-off on longitudinal momentum. We show that when all the renormalization constants are combined, the ultraviolet divergences can be absorbed into the standard QCD running coupling constant, and give an explicit expression for the remaining finite part.
Relativistic correction to gluon fragmentation function into pseudoscalar quarkonium
NASA Astrophysics Data System (ADS)
Gao, Xiangrui; Jia, Yu; Li, Liuji; Xiong, Xiaonu
2017-02-01
Inspired by the recent measurements of the ηc meson production at LHC experiments, we investigate the relativistic correction effect for the fragmentation functions of gluon/charm quark fragmenting into ηc, which constitute the crucial nonperturbative element for the ηc production at high p T. Employing three distinct methods, we calculate the next-to-leading-order (NLO) relativistic correction to g → ηc fragmentation function in the NRQCD factorization framework, as well as verifying the existing NLO result for the c → ηc fragmentation function. We also study the evolution behavior of these fragmentation functions with the aid of the DGLAP equation. Supported by National Natural Science Foundation of China (11475188, 11261130311, 11575202, 11222549), IHEP Innovation (Y4545170Y2), State Key Lab for Electronics and Particle Detectors
Experimental Studies of Quark Gluon Plasma at RHIC
NASA Astrophysics Data System (ADS)
Esumi, ShinIchi
2010-05-01
A new state of matter, Quark Gluon Plasma (QGP) is supposed to exist under extreme temperature and/or density conditions just as a beginning of this early universe after the Big Bang. High energy nucleus-nucleus collisions at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been used to form the QGP and to study the properties of QGP. The recent progress on the experimental research of QGP at RHIC experiments and the understanding of the properties are discussed. Major discoveries at RHIC experiments are very strong energy loss of high energy partons in central Au+Au collisions and very large elliptic and collective expansion given by the initial almond geometry in non-central Au+Au collisions. Those two finding and related physics explanations as well as future plans are presented.
Experimental Studies of Quark Gluon Plasma at RHIC
Esumi, ShinIchi
2010-05-12
A new state of matter, Quark Gluon Plasma (QGP) is supposed to exist under extreme temperature and/or density conditions just as a beginning of this early universe after the Big Bang. High energy nucleus-nucleus collisions at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been used to form the QGP and to study the properties of QGP. The recent progress on the experimental research of QGP at RHIC experiments and the understanding of the properties are discussed. Major discoveries at RHIC experiments are very strong energy loss of high energy partons in central Au+Au collisions and very large elliptic and collective expansion given by the initial almond geometry in non-central Au+Au collisions. Those two finding and related physics explanations as well as future plans are presented.
Gluon structure function of a color dipole in the light-cone limit of lattice QCD
Gruenewald, D.; Ilgenfritz, E.-M.; Pirner, H. J.
2009-10-01
We calculate the gluon structure function of a color dipole in near-light-cone SU(2) lattice QCD as a function of x{sub B}. The quark and antiquark are external nondynamical degrees of freedom which act as sources of the gluon string configuration defining the dipole. We compute the color dipole matrix element of transversal chromo-electric and chromo-magnetic field operators separated along a direction close to the light cone, the Fourier transform of which is the gluon structure function. As vacuum state in the pure glue sector, we use a variational ground state of the near-light-cone Hamiltonian. We derive a recursion relation for the gluon structure function on the lattice similar to the perturbative Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation. It depends on the number of transversal links assembling the Schwinger string of the dipole. Fixing the mean momentum fraction of the gluons to the 'experimental value' in a proton, we compare our gluon structure function for a dipole state with four links with the next-to-leading-order MRST 2002 and the CTEQ AB-0 parametrizations at Q{sup 2}=1.5 GeV{sup 2}. Within the systematic uncertainty we find rather good agreement. We also discuss the low x{sub B} behavior of the gluon structure function in our model calculation.
Two-gluon emission and interference in a thin QCD medium: insights into jet formation
NASA Astrophysics Data System (ADS)
Casalderrey-Solana, Jorge; Pablos, Daniel; Tywoniuk, Konrad
2016-11-01
In heavy-ion collisions, an abundant production of high-energy QCD jets allows to study how these multiparticle sprays are modified as they pass through the quark-gluon plasma. In order to shed new light on this process, we compute the inclusive two-gluon rate off a hard quark propagating through a color deconfined medium at first order in medium opacity. We explicitly impose an energy ordering of the two emitted gluons, such that the "hard" gluon can be thought of as belonging to the jet substructure while the other is a "soft" emission (which can be collinear or medium-induced). Our analysis focusses on two specific limits that clarify the modification of the additional angle- and formation time-ordering of splittings. In one limit, the formation time of the "hard" gluon is short compared to the "soft" gluon formation time, leading to a probabilistic formula for production of and subsequent radiation off a quark-gluon antenna. In the other limit, the ordering of formation is reverted, which automatically leads to the fact that the jet substructure is resolved by the medium. We observe in this case a characteristic delay: the jet radiates as one color current (quark) up to the formation of the "hard" gluon, at which point we observe the onset of radiation of the new color current (gluon). Within our kinematic constraints, our computation supports a picture in which the in-medium jet dynamics are described as a collection of subsequent antennas which are resolved by the medium according to their transverse extent.
Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation
Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng
2016-05-01
In this paper we study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. Lastly, the presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.
Probing the twist-3 multi-gluon correlation functions by p↑p → DX
NASA Astrophysics Data System (ADS)
Koike, Yuji; Yoshida, Shinsuke
2011-05-01
We study the single spin asymmetry (SSA) for the D-meson production ADN in the pp collision, p↑p → DX in the framework of the collinear factorization. Since the charm quark is mainly produced through the cbar c-pair creation from the gluon-fusion process, this is an ideal process to probe the twist-3 triple-gluon correlation functions in the polarized nucleon. We derive the corresponding cross section formula for the contribution of the triple-gluon correlation function to ADN in p↑p → DX, applying the method developed for ep↑ → eDX in our previous study. As in the case of ep↑ → eDX, our result differs from a previous study in the literature.We will also present a simple estimate of the triple-gluon correlation functions based on the preliminary data on ADN by RHIC.
Thermalization of mini-jets in a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Iancu, Edmond; Wu, Bin
2016-12-01
We present the complete physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma (QGP) by analytical and numerical investigation of thermalization of the soft components of the jet. Our results support the following physical picture: the leading particle emits a significant number of mini-jets which promptly evolve via multiple branching and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature T. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. Together with the background QGP, they behave hydrodynamically.
Study of enhancing a hadronic search for supersymmetry with quark/gluon discrimination
NASA Astrophysics Data System (ADS)
Penafiel, Louis
2017-01-01
We present studies of applying quark/gluon discrimination in the context of searches for supersymmetry in all hadronic final states with data from the Compact Muon Solenoid experiment. We compare the sensitivity of an established search with a search that utilizes the additional information from quark/gluon discrimination. Results are shown for several simplified model signal topologies. With support from the Chancellor's Research Fellowship of University of California, Riverside.
Non-perturbative effects for the Quark-Gluon Plasma equation of state
NASA Astrophysics Data System (ADS)
Begun, V. V.; Gorenstein, M. I.; Mogilevsky, O. A.
2012-07-01
The non-perturbative effects for the Quark-Gluon Plasma (QGP) equation of state (EoS) are considered. The modifications of the bag model EoS are constructed to satisfy the main qualitative features observed for the QGP EoS in the lattice QCD calculations. A quantitative comparison with the lattice results is done for the SU(3) gluon plasma and for the QGP with dynamical quarks. Our analysis advocates a negative value of the bag constant B.
Self-consistent one-gluon exchange in soliton bag models
NASA Astrophysics Data System (ADS)
Dodd, L. R.; Williams, A. G.
1988-08-01
The treatment of soliton bag models as two-point boundary value problems is extended to include self-consistent one-gluon exchange interactions. The colour-magnetic contribution to the nucleon-delta mass splitting is calculated self-consistently in the mean-field, one-gluon-exchange approximation for the Friedberg-Lee and Nielsen-Patkos models. Small glueball mass parameters (mGB~500 MeV) are favoured. Comparisons with previous calculations are made.
Effects of dynamical FLIC fermions in the quark and gluon propagator
NASA Astrophysics Data System (ADS)
Kamleh, W.; Bowman, P. O.; Leinweber, D. B.; Williams, A. G.; Zhang, J.-B.
2006-11-01
In this work we examine the FLIC overlap quark propagator and the gluon propagator on both dynamical and quenched lattices. The tadpole improved Luscher-Weisz gauge action is used in both cases. The dynamical gauge fields use the FLIC fermion action for the sea quark contribution. We observe that the presence of sea quarks causes a suppression of the mass function, quark renormalisation function and gluon dressing function in the infrared. The ultraviolet physics is unaffected.
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…
Chiral electric separation effect in the quark-gluon plasma
Jiang, Yin; Liao, Jinfeng; Huang, Xu-Guang
2015-02-02
In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient σ_{χe}, the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current J_{A} that is generated in response to an externally applied electric field eE: J_{A}=σ_{χe}(eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure σ_{χe}∝μμ5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density μ5 ≠ 0. Using the Hard-Thermal-Loop framework, the CESE conductivity for the QGP is found to be σ_{χe} = (#)TT_{rf}Q_{e}Q_{A}/g⁴ln(1/g) μμ5/T² to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.
The approach to equilibrium in a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Heinz, U.
The basic questions to be addressed in this paper are: How does the quark-gluon plasma, once formed in heavy-ion collisions, approach equilibrium. What are the basic equilibrium time scales - how do they compare with the plasma lifetime before hadronization and freeze-out set in. In particular, how do the strong color anisotropies, which are presumably present in the initial formation stage disappear and how fast, if at all, do the color degrees of freedom attain local equilibrium. The approach that I wish to present here involves the following chain of arguments: equilibration is related to dissipation of energy and creation of entropy; it is determined by the dissipative, i.e., imaginary part of certain response functions - for example, to calculate the rate of dissipation for a density perturbation in an equilibrium plasma we need to work out the imaginary part of the retarded density-density correlation function; this imaginary part of the response function is dominated by its poles which signal collective modes - for example, phonons in the density-density correlation function, (colored) plasmons in the electric and magnetic response functions, etc.; from the imaginary part one can calculate a damping rate gamma for these collective modes which in turn yields an estimate for the equilibration time scale tau/sub equ/ is approximately h-bar/gamma. In this contribution I will concentrate on color equilibration and thus focus on color electric and magnetic plasma oscillations and their damping rates.
Natural constraints on the gluon-quark vertex
NASA Astrophysics Data System (ADS)
Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis; Qin, Si-Xue; Roberts, Craig D.
2017-02-01
In principle, the strong-interaction sector of the standard model is characterized by a unique renormalization-group-invariant (RGI) running interaction and a unique form for the dressed-gluon-quark vertex, Γμ; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansätze for Γμ. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Evidently, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansätze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.
Measuring the aspect ratio renormalization of anisotropic-lattice gluons
Alford, M.; Drummond, I. T.; Horgan, R. R.; Shanahan, H.; Peardon, M.
2001-04-01
Using tadpole-improved actions we investigate the consistency between different methods of measuring the aspect ratio renormalization of anisotropic-lattice gluons for bare aspect ratios {chi}{sub 0}=4,6,10 and inverse lattice spacing in the range a{sub s}{sup -1}=660--840 MeV. The tadpole corrections to the action, which are established self-consistently, are defined for two cases, mean link tadpoles in the Landau gauge and gauge invariant mean plaquette tadpoles. Parameters in the latter case exhibited no dependence on the spatial lattice size L, while in the former, parameters showed only a weak dependence on L easily extrapolated to L={infinity}. The renormalized anisotropy {chi}{sub R} was measured using both the torelon dispersion relation and the sideways potential method. There is general agreement between these approaches, but there are discrepancies which are evidence for the presence of lattice artifact contributions. For the torelon these are estimated to be O({alpha}{sub S}a{sub s}{sup 2}/R{sup 2}), where R is the flux-tube radius. We also present some new data that suggest that rotational invariance is established more accurately for the mean-link action than the plaquette action.
Chiral electric separation effect in the quark-gluon plasma
Jiang, Yin; Liao, Jinfeng; Huang, Xu-Guang
2015-02-02
In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient σχe, the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current JA that is generated in response to an externally applied electric field eE: JA=σχe(eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure σχe∝μμ5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density μ5 ≠ 0. Using the Hard-Thermal-Loop framework, the CESEmore » conductivity for the QGP is found to be σχe = (#)TTrfQeQA/g⁴ln(1/g) μμ5/T² to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.« less
Resolving gluon fusion loops at current and future hadron colliders
NASA Astrophysics Data System (ADS)
Azatov, Aleksandr; Grojean, Christophe; Paul, Ayan; Salvioni, Ennio
2016-09-01
Inclusive Higgs measurements at the LHC have limited resolution on the gluon fusion loops, being unable to distinguish the long-distance contributions mediated by the top quark from possible short-distance new physics effects. Using an Effective Field Theory (EFT) approach we compare several proposed methods to lift this degeneracy, including toverline{t}h and boosted, off-shell and double Higgs production, and perform detailed projections to the High-Luminosity LHC and a future hadron collider. In addition, we revisit off-shell Higgs production. Firstly, we point out its sensitivity to modifications of the top- Z couplings, and by means of a general analysis we show that the reach is comparable to that of tree-level processes such as toverline{t}Z production. Implications for composite Higgs models are also discussed. Secondly, we assess the regime of validity of the EFT, performing an explicit comparison for a simple extension of the Standard Model containing one vector-like quark.
Lee, HyeongJin; Ahn, SeungHyun; Bonassar, Lawrence J.; Chun, Wook
2013-01-01
Generally, solid-freeform fabricated scaffolds show a controllable pore structure (pore size, porosity, pore connectivity, and permeability) and mechanical properties by using computer-aided techniques. Although the scaffolds can provide repeated and appropriate pore structures for tissue regeneration, they have a low biological activity, such as low cell-seeding efficiency and nonuniform cell density in the scaffold interior after a long culture period, due to a large pore size and completely open pores. Here we fabricated three different poly(ɛ-caprolactone) (PCL)/alginate scaffolds: (1) a rapid prototyped porous PCL scaffold coated with an alginate, (2) the same PCL scaffold coated with a mixture of alginate and cells, and (3) a multidispensed hybrid PCL/alginate scaffold embedded with cell-laden alginate struts. The three scaffolds had similar micropore structures (pore size=430–580 μm, porosity=62%–68%, square pore shape). Preosteoblast cells (MC3T3-E1) were used at the same cell density in each scaffold. By measuring cell-seeding efficiency, cell viability, and cell distribution after various periods of culturing, we sought to determine which scaffold was more appropriate for homogeneously regenerated tissues. PMID:23469894
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.
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.
Critical exponents of the quark-gluon bags model with a critical endpoint
NASA Astrophysics Data System (ADS)
Ivanytskyi, A. I.; Bugaev, K. A.; Sorin, A. S.; Zinovjev, G. M.
2012-12-01
The critical indices α', β, γ', and δ of the Quark Gluon Bags with Surface Tension Model that has a critical endpoint are calculated and compared with the exponents of other models. These indices are expressed in terms of the most general parameters of the model. Despite the usual expectations the found critical indices do not depend on the Fisher exponent τ and on the parameter ϰ which relates the mean bag surface to its volume. The scaling relations for the obtained critical exponents are verified, and it is demonstrated that for the standard definition of the index α' the Fisher and the Griffiths scaling inequalities are not fulfilled in general case, whereas the Liberman scaling inequality is always obeyed. This is not surprising for the phase diagram with the asymmetric properties of pure phases, but the present model also provides us with the first and explicit example that the specially defined index αs' does not recover the scaling relations as well. Therefore, here we suggest the physically motivated definition of the index α'=αc' and demonstrate that such a definition recovers the Fisher scaling inequality, while it is shown that the Griffiths inequality should be generalized for the phase diagram with the asymmetric properties. The critical exponents of several systems that belong to different universality classes are successfully described by the parameters of the present model, and hence its equation of state can be used for a variety of practical applications.
Suppression of Baryon Diffusion and Transport in a Baryon Rich Strongly Coupled Quark-Gluon Plasma.
Rougemont, Romulo; Noronha, Jorge; Noronha-Hostler, Jacquelyn
2015-11-13
Five dimensional black hole solutions that describe the QCD crossover transition seen in (2+1)-flavor lattice QCD calculations at zero and nonzero baryon densities are used to obtain predictions for the baryon susceptibility, baryon conductivity, baryon diffusion constant, and thermal conductivity of the strongly coupled quark-gluon plasma in the range of temperatures 130 MeV≤T≤300 MeV and baryon chemical potentials 0≤μ(B)≤400 MeV. Diffusive transport is predicted to be suppressed in this region of the QCD phase diagram, which is consistent with the existence of a critical end point at larger baryon densities. We also calculate the fourth-order baryon susceptibility at zero baryon chemical potential and find quantitative agreement with recent lattice results. The baryon transport coefficients computed in this Letter can be readily implemented in state-of-the-art hydrodynamic codes used to investigate the dense QGP currently produced at RHIC's low energy beam scan.
Gluon mass generation and infrared Abelian dominance in Yang-Mills theory
NASA Astrophysics Data System (ADS)
Shibata, Akihiro
2006-12-01
Dual superconductivity is believed to be a promising mechanism for quark confinement. Indeed, that this picture is true has been confirmed in the maximal Abelian (MA) gauge. However, it is not yet confirmed in any other gauge, and the MA gauge explicitly breaks color symmetry. To remedy this defect, we propose to use our compact formulation of a non-linear change of variables (NLCV), called once by the Cho-Faddeev-Niemi (CFN) decomposition, on a lattice. This formulation has succeeded to extract the magnetic monopole with integer-valued magnetic charge in the gauge-invariant way. We present measurements of various correlation functions for the operators constructed from the NLCV in SU(2) Yang-Mills theory. Some of our results reproduce previous results obtained in MA gauge, e.g., DeGrand-Toussaint monopole, infrared Abelian dominance and off-diagonal gluon mass generation. These studies preserve color symmetry, which is sharp contrast to the conventional MA gauge. We argue the gauge fixing independence of these results and the implications for quark confinement
Borowka, S; Greiner, N; Heinrich, G; Jones, S P; Kerner, M; Schlenk, J; Schubert, U; Zirke, T
2016-07-01
We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.
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.
Unified description of seagull cancellations and infrared finiteness of gluon propagators
NASA Astrophysics Data System (ADS)
Aguilar, A. C.; Binosi, D.; Figueiredo, C. T.; Papavassiliou, J.
2016-08-01
We present a generalized theoretical framework for dealing with the important issue of dynamical mass generation in Yang-Mills theories, and, in particular, with the infrared finiteness of the gluon propagators, observed in a multitude of recent lattice simulations. Our analysis is manifestly gauge invariant, in the sense that it preserves the transversality of the gluon self-energy, and gauge independent, given that the conclusions do not depend on the choice of the gauge-fixing parameter within the linear covariant gauges. The central construction relies crucially on the subtle interplay between the Abelian Ward identities satisfied by the nonperturbative vertices and a special integral identity that enforces a vast number of "seagull cancellations" among the one- and two-loop dressed diagrams of the gluon Schwinger-Dyson equation. The key result of these considerations is that the gluon propagator remains rigorously massless, provided that the vertices do not contain (dynamical) massless poles. When such poles are incorporated into the vertices, under the pivotal requirement of respecting the gauge symmetry of the theory, the terms comprising the Ward identities conspire in such a way as to still enforce the total annihilation of all quadratic divergences, inducing, at the same time, residual contributions that account for the saturation of gluon propagators in the deep infrared.
Dynamical chiral symmetry breaking and confinement with an infrared-vanishing gluon propagator
Roberts, C.D.; Hawes, F.T.; Williams, A.G.
1995-08-01
We have studied a model Dyson-Schwinger equation for the quark propagator, constructed using an Ansatz for the gluon propagator of the form D(q) {approximately} q{sup 2}/[(q{sup 2}){sup 2} + b{sup 4}] and two Ansatze for the quark-gluon vertex: the minimal Ball-Chiu and the modified form suggested by Curtis and Pennington. The aim was to determine whether such a form of the gluon propagator, which was suggested by a number of authors and which recent lattice simulations of QCD suggest may be plausible, can support dynamical chiral symmetry breaking and ensure quark confinement. The form of the gluon propagator at small space-like momenta is crucial to the nature of the strong interaction spectrum but is presently unknown and information gathered in such studies is invaluable in supporting or invalidating given hypotheses. It was found that there is a critical value of b = b{sub c} such that the model does not support dynamical chiral symmetry breaking for b > b{sub c}. Further, it was shown that this form of gluon propagator cannot confine quarks. As a consequence this form represents a physically unreasonable model. In addition, these results formed the basis for an invited presentation at a workshop on quantum infrared physics and will be published in the proceedings.
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.
Collective flow signals the quark-gluon plasma
NASA Astrophysics Data System (ADS)
Stöcker, H.
2005-03-01
A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A GeV: here the hydrodynamic model has predicted the collapse of the v-flow and of the v-flow at ˜10 A GeV; at 40 A GeV it has been recently observed by the NA49 Collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as evidence for a first order phase transition at high baryon density ρ. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Here, hadronic rescattering models can explain <30% of the observed elliptic flow, v, for p>2 GeV/c. This is interpreted as evidence for the production of superdense matter at RHIC with initial pressure far above hadronic pressure, p>1 GeV/fm. We suggest that the fluctuations in the flow, v and v, should be measured in future since ideal hydrodynamics predicts that they are larger than 50% due to initial state fluctuations. Furthermore, the QGP coefficient of viscosity may be determined experimentally from the fluctuations observed. The connection of v to jet suppression is examined. It is proven experimentally that the collective flow is not faked by minijet fragmentation. Additionally, detailed transport studies show that the away-side jet suppression can only partially (<50%) be due to hadronic rescattering. We, finally, propose upgrades and second generation experiments at RHIC which inspect the first order phase transition in the fragmentation region, i.e., at μ≈400 MeV ( y≈4-5), where the collapse of the proton flow should be seen in analogy to the 40 A GeV data. The study of Jet-Wake-riding potentials and Bow shocks—caused by jets in the QGP formed at RHIC—can give further information on the equation of state (EoS) and transport coefficients of the quark-gluon plasma
Resummation of soft gluon logarithms in the DGLAP evolution of fragmentation functions
NASA Astrophysics Data System (ADS)
Albino, S.; Kniehl, B. A.; Kramer, G.; Ochs, W.
2006-03-01
We define a general scheme for the evolution of fragmentation functions which resums both soft gluon logarithms and mass singularities in a consistent manner and to any order, and requires no additional theoretical assumptions. Using the double logarithmic approximation and the known perturbative results for the splitting functions, we present our scheme with the complete contribution from the double logarithms, being the largest soft gluon logarithms. We show that the resulting approximation is more complete than the modified leading logarithm approximation even with the fixed order contribution calculated to leading order only, and find, after using it to fit quark and gluon fragmentation functions to experimental data, that this approximation in our scheme gives a good description of the data from the largest xp values to the peak region in ξ=ln(1/xp), in contrast to other approximations. In addition, we develop a treatment of hadron mass effects which gives additional improvements at large ξ.
QCD fixed points: Banks-Zaks scenario or dynamical gluon mass generation?
NASA Astrophysics Data System (ADS)
Gomez, J. D.; Natale, A. A.
2017-01-01
Fixed points in QCD can appear when the number of quark flavors (Nf) is increased above a certain critical value as proposed by Banks and Zaks (BZ). There is also the possibility that QCD possess an effective charge indicating an infrared frozen coupling constant. In particular, an infrared frozen coupling associated to dynamical gluon mass (DGM) generation does lead to a fixed point even for a small number of quarks. We compare the BZ and DGM mechanisms, their β functions and fixed points, and within the approximations of this work, which rely basically on extrapolations of the dynamical gluon masses at large Nf, we verify that between Nf = 8 and Nf = 12 both cases exhibit fixed points at similar coupling constant values (g∗). We argue that the states of minimum vacuum energy, as a function of the coupling constant up to g∗ and for several Nf values, are related to the dynamical gluon mass generation mechanism.
Resummation of soft gluon logarithms in the DGLAP evolution of fragmentation functions
Albino, S.; Kniehl, B.A.; Kramer, G.; Ochs, W.
2006-03-01
We define a general scheme for the evolution of fragmentation functions which resums both soft gluon logarithms and mass singularities in a consistent manner and to any order, and requires no additional theoretical assumptions. Using the double logarithmic approximation and the known perturbative results for the splitting functions, we present our scheme with the complete contribution from the double logarithms, being the largest soft gluon logarithms. We show that the resulting approximation is more complete than the modified leading logarithm approximation even with the fixed order contribution calculated to leading order only, and find, after using it to fit quark and gluon fragmentation functions to experimental data, that this approximation in our scheme gives a good description of the data from the largest x{sub p} values to the peak region in {xi}=ln(1/x{sub p}), in contrast to other approximations. In addition, we develop a treatment of hadron mass effects which gives additional improvements at large {xi}.
Building a non-perturbative quark-gluon vertex from a perturbative one
NASA Astrophysics Data System (ADS)
Bermudez, Rocio
2016-10-01
The quark-gluon vertex describes the electromagnetic and the strong interaction among these particles. The description of this interaction at high precision in both regimes, perturbative and non-perturbative, continues being a matter of interest in the context of QCD and Hadron Physics. There exist very helpful models in the literature that explain perturbative aspects of the theory but they fail describing non-perturbative phenomena, as confinement and dynamic chiral symmetry breaking. In this work we study the structure of the quark-gluon vertex in a non-perturbative regime examining QCD, checking results with QED, and working in the Schwinger-Dyson formalism.
Colour-Octet-Annihilation in Leading Neutral Systems of Gluon Jets
Buschbeck, B.; Mandl, F.
2007-11-19
Using data of the DELPHI collaboration the electric charges of Leading Systems (defined by a rapidity gap) in quark and gluon jets are measured and are compared with the results from Monte Carlo simulations which do not contain colour-octet neutralistion processes. In the data an enhanced production of neutral Leading Systems compared to the Monte Carlo predictions is found in gluon jets. This excess and its location at low masses ({<=}2 GeV/c{sup 2}) of the neutral Leading System is expected for colour-octet neutralistion. The quark jets are found to be in agreement with the simulation.
Open-beauty production in pPb collisions at √{sNN}=5 TeV: Effect of the gluon nuclear densities
NASA Astrophysics Data System (ADS)
Conesa del Valle, Z.; Ferreiro, E. G.; Fleuret, F.; Lansberg, J. P.; Rakotozafindrabe, A.
2014-06-01
We present our results on open-beauty production in proton-nucleus collisions for the recent LHC pPb run at √{sNN}=5 TeV. We have analyzed the effect of the modification of the gluon PDFs in a nucleus at the level of the nuclear modification factor. Because of the absence of measurements in pp collisions at the same collision energy, √{sNN}, we also propose the study of the forward-to-backward yield ratio in which the unknown proton-proton yield cancels. Our results are compared with the data obtained by the LHCb collaboration and show a good agreement.
Peturbative gluon exchange in a covariant quark model of the pion
Ito, Hiroshi; Buck, W.W. . Dept. of Physics); Gross, F. . Dept. of Physics Continuous Electron Beam Accelerator Facility, Newport News, VA )
1990-01-01
A covariant pion wave function, which reproduces the low energy data, is used to calculate the perturbative gluon exchange contributions to the pion charge form factor. It is found that the perturbative process dominates at q > 3.5 GeV/c. The dependence on the quark mass and the asymptotic behavior of the form factor are explicitly displayed.
The one-gluon exchange effects to gA/gV of baryon semileptonic decay
NASA Astrophysics Data System (ADS)
Ushio, K.; Konashi, H.
1984-02-01
The one-gluon exchange effects to gA/gV of the processes, B --> B' + l + vl are investigated in the MIT bag model. Their contributions are rather consistent with the data. Sonodagakuen Women's Junior College, Minamitsukaguchicho, Amagasaki 601, Japan.
Supersymmetric Model of ρ-Meson Propagator in Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Rostampour, M.; Saadat, H.
2012-08-01
In this work we study supersymmetric model of ρ-meson propagation in quark-gluon plasma. Then we apply this method to total absorption cross sections of photon and photino. We use supersymmetric condition to find that absorption cross sections of photon should be equal to absorption cross sections of photino.
Equation of state of a quark-gluon plasma using the Cornell potential
NASA Astrophysics Data System (ADS)
Udayanandan, K. M.; Sethumadhavan, P.; Bannur, V. M.
2007-10-01
The equation of state (EOS) of quark-gluon plasma (QGP) using the Cornell potential based on Mayer's cluster expansion is presented. The string constant and the strong coupling constant for QGP are calculated. The EOS developed could describe the lattice EOS for pure gauge, two-flavor and three-flavor QGP qualitatively.
Glueballs, gluon condensate, and pure glue QCD below T{sub c}
Buisseret, F.
2011-05-23
A quasiparticle description of pure glue QCD below T{sub c} is presented. It is shown that the strong decrease of both the gluon condensate and the lightest glueball masses when approaching T{sub c} might be the trigger of the phase transition. The proposed model compares favorably with recent lattice data.
Maximal Wavelength of Confined Quarks and Gluons and Properties of Quantum Chromodynamics
Brodsky, Stanley J.; Shrock, Robert; /YITP, Stony Brook
2008-08-01
Because quarks and gluons are confined within hadrons, they have a maximum wavelength of order the confinement scale. Propagators, normally calculated for free quarks and gluons using Dyson-Schwinger equations, are modified by bound-state effects in close analogy to the calculation of the Lamb shift in atomic physics. Because of confinement, the effective quantum chromodynamic coupling stays finite in the infrared. The quark condensate which arises from spontaneous chiral symmetry breaking in the bound state Dyson-Schwinger equation is the expectation value of the operator {bar q}q evaluated in the background of the fields of the other hadronic constituents, in contrast to a true vacuum expectation value. Thus quark and gluon condensates reside within hadrons. The effects of instantons are also modified. We discuss the implications of the maximum quark and gluon wavelength for phenomena such as deep inelastic scattering and annihilation, the decay of heavy quarkonia, jets, and dimensional counting rules for exclusive reactions. We also discuss implications for the zero-temperature phase structure of a vectorial SU(N) gauge theory with a variable number N{sub f} of massless fermions.
Dynamical chiral symmetry breaking and confinement with an infrared-vanishing gluon propagator
Hawes, F.T. ); Roberts, C.D. ); Williams, A.G. )
1994-05-01
We study a model Dyson-Schwinger equation for the quark propagator closed using an [ital Ansatz] for the gluon propagator of the form [ital D]([ital q])[similar to][ital q][sup 2]/[([ital q][sup 2])[sup 2]+[ital b][sup 4
Implementation of Recursion Relations in Gluon Scattering Amplitude Calculations in AdS4 /CFT3
NASA Astrophysics Data System (ADS)
Dokmetzoglou, Nikolaos; Kharel, Savan
2017-01-01
The Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence is a duality between a theory of gravity in curved-space (AdS) and a conformally-invariant quantum field theory in flat-space (CFT). Scattering amplitudes are observables associated with the probability of the interaction of a given assembly of particles. Gluons, being the exchange particles associated with the strong nuclear force, which holds quarks together to form protons, are abundant byproducts of fundamental particle collisions. Thus, studying gluon scattering amplitudes is an effective way of deepening our understanding of these observables in AdS/CFT. Traditionally, Feynman diagrams have been used to calculate such scattering amplitudes. In this project, we use factorization properties and recursion relations to simplify these calculations. More specifically, we calculate multiple (different helicity combinations) four-point gluon scattering amplitudes in AdS4 /CFT3 (4-D AdS and 3-D CFT) as sums of products of three-point amplitudes. And then we calculate a five-point gluon scattering amplitude in AdS4 /CFT3 by decomposing it into a sum of products of these four-point and three-point amplitudes. Finally we comment on useful identities for checking these amplitudes. This work was supported by a Weinstein Davidson College Research Initiative Summer Research grant.
A physical meaning of mixed gluon-ghost condensate of mass dimension two
NASA Astrophysics Data System (ADS)
Kondo, Kei-Ichi
2003-10-01
We demonstrate that a clear physical content and relevance can be attributed to the on-shell BRST-invariant mixed gluon-ghost condensate of mass dimension two which was recently proposed by the author. We argue that a gauge invariant observable is associated with the mixed condensate.
Heavy quark quenching from RHIC to LHC and the consequences of gluon damping
NASA Astrophysics Data System (ADS)
Gossiaux, P. B.; Nahrgang, M.; Bluhm, M.; Gousset, Th.; Aichelin, J.
2013-05-01
In this contribution to the Quark Matter 2012 conference, we study whether energy loss models established for RHIC energies to describe the quenching of heavy quarks can be applied at LHC with the same success. We also benefit from the larger pT-range accessible at this accelerator to test the impact of gluon damping on observables such as the nuclear modification factor.
Bulk viscosity of quark-gluon matter in a magnetic field
Agasian, N. O.
2013-11-15
On the basis of low-energy QCD theorems, the bulk viscosity {zeta}(T, Micro-Sign , H) is expressed in terms of basic thermodynamic quantities that characterizes quark-gluon matter at finite temperature and a finite baryon density in a magnetic field. Various limiting cases are considered.
Gulyás, Balázs; Spenger, Christian; Beliczai, Zsuzsa; Gulya, Károly; Kása, Péter; Jahan, Mahabuba; Jia, Zhisheng; Weber, Urs; Pfeifer, Andrea; Muhs, Andreas; Willbold, Dieter; Halldin, Christer
2012-01-01
One of the major pathological landmarks of Alzheimer's disease and other neurodegenerative diseases is the presence of amyloid deposits in the brain. The early non-invasive visualization of amyloid is a major objective of recent diagnostic neuroimaging approaches, including positron emission tomography (PET), with an eye on follow-up of disease progression and/or therapy efficacy. The development of molecular imaging biomarkers with binding affinity to amyloid in the brain is therefore in the forefront of imaging biomarker and radiochemistry research. Recently, a dodecamer peptide (amino acid sequence=QSHYRHISPAQV; denominated D1 or ACI-80) was identified as a prospective ligand candidate, binding with high ex vivo affinity to L-Aβ-amyloid (K(d): 0.4 μM). In order to assess the ligand's capacity to visualize amyloid in Alzheimer's disease (AD), two (125)I labeled and three (18)F labeled analogues of the peptide were synthesized and tested in post mortem human autoradiography experiments using whole hemisphere brain slices obtained from deceased AD patients and age matched control subjects. The (18)F-labeled radioligands showed more promising visualization capacity of amyloid that the (125)I-labeled radioligands. In the case of each (18)F radioligands the grey matter uptake in the AD brains was significantly higher than that in control brains. Furthermore, the grey matter: white matter uptake ratio was over ~2, the difference being significant for each (18)F-radioligands. The regional distribution of the uptake of the various radioligands systematically shows a congruent pattern between the high uptake regions and spots in the autoradiographic images and the disease specific signals obtained in adjacent or identical brain slices labeled with histological, immunohistochemical or autoradiographic stains for amyloid deposits or activated astrocytes. The present data, using post mortem human brain autoradiography in whole hemisphere human brains obtained from deceased
Baryon scattering at high energies: wave function, impact factor, and gluon radiation
NASA Astrophysics Data System (ADS)
Bartels, J.; Motyka, L.
2008-05-01
The scattering of a baryon consisting of three massive quarks is investigated in the high energy limit of perturbative QCD. A model of a relativistic proton-like wave function, dependent on valence quark longitudinal and transverse momenta and on quark helicities, is proposed, and we derive the baryon impact factors for two, three and four t-channel gluons. We find that the baryonic impact factor can be written as a sum of three pieces: in the first one a subsystem consisting of two of the three quarks behaves very much like the quark antiquark pair in γ* scattering, whereas the third quark acts as a spectator. The second term belongs to the odderon, whereas in the third (C-even) piece all three quarks participate in the scattering. This term is new and has no analogue in γ* scattering. We also study the small x evolution of gluon radiation for each of these three terms. The first term follows the same pattern of gluon radiation as the γ*-initiated quark antiquark dipole, and, in particular, it contains the BFKL evolution followed by the 2→4 transition vertex (triple pomeron vertex). The odderon term is described by the standard BKP evolution, and the baryon couples to both known odderon solutions, the Janik Wosiek solution and the BLV solution. Finally, the t-channel evolution of the third term starts with a three-reggeized gluon state, which then, via a new 3→4 transition vertex, couples to the four-gluon (two-pomeron) state. We briefly discuss a few consequences of these findings, in particular the pattern of unitarization of high energy baryon scattering amplitudes.
Gluon fusion and b b bar corrections to HW+W-/HZZ production in the POWHEG-BOX
NASA Astrophysics Data System (ADS)
Baglio, Julien
2017-01-01
The study of the Higgs boson properties is one of the most important tasks to be accomplished in the next years, at the Large Hadron Collider (LHC) and at future colliders such as the Future Circular Collider in hadron-hadron mode (FCC-hh), the potential 100 TeV follow-up of the LHC machine. In this view the precise study of the Higgs couplings to weak gauge bosons is crucial and requires as much information as possible. After the recent calculation of the next-to-leading order QCD corrections to the production cross sections and differential distributions of a Standard Model Higgs boson in association with a pair of weak bosons, matched with parton shower in the POWHEG-BOX framework, we present the gluon fusion correction gg → HW+W- (HZZ) to the process pp → HW+W- (HZZ). This correction can be sizeable and amounts to + 3% (+ 10%) in the HW+W- process and + 5% (+ 18%) in the HZZ process at the LHC (FCC-hh). We also present the first study of the impact of the bottom-quark initiated channels b b bar → HW+W- / HZZ and find that they induce a significant + 18% correction in the HW+W- channel at the FCC-hh. We present results on total cross sections and distributions at the LHC and at the FCC-hh.
NASA Astrophysics Data System (ADS)
Ivanov, I. P.; Nikolaev, N. N.
2002-03-01
The differential gluon structure function of the proton F(x,Q2) introduced by Fadin, Kuraev, and Lipatov in 1975 is used in many applications of small-x QCD. We report here ready-to-use parametrizations of F(x,Q2) from the κ-factorization phenomenology of the experimental data on the small-x proton structure function F2p(x,Q2). These parametrizations are based partly on the available Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution fits [Glück-Reya-Vogt, Coordinated Theoretical/Experimental Project on QCD Phenomenology (CTEQ), and Martin-Roberts-Stirling] to parton distribution functions and on realistic extrapolations into a soft region. We discuss the impact of soft gluons on various observables. The x dependence of the F(x,Q2) so determined varies strongly with Q2 and does not exhibit simple Regge properties. Nonetheless, the hard-to-soft diffusion is found to give rise to a viable approximation of the proton structure function F2p(x,Q2) by the soft and hard Regge components with intercepts Δsoft=0 and Δhard~0.4.
NASA Astrophysics Data System (ADS)
Muñoz, M.; Fournier, H.; Mamani, M.; Febrer, J.; Borzotta, E.; Maidana, A.
The first magnetotelluric deep soundings in Chile were carried out during 1986 in the Villarrica active volcano zone (39°25'S, 71°57'W). In the TM mode of polarization, the curves show a distorted segment with dispersion. A static distortion at long periods is observed in curves in the TE mode of polarization; the segment was shifted vertically to fit the geomagnetic global model values at daily periods. This modified curve was used for 1D modelling to determine the electrical structure in the study area. The upper level of the intermediate conducting layer of resistivity 20-60 ω m is found to be at 35-50 km depth. A higher resistivity layer (600 ω m), starting at 100 km depth, may be resolved in the intermediate conducting layer. A sharp decrease in the resistivity is shown by the model at 500 km. Large heterogeneities at the level of the conducting layer encountered in the 1D modelling, and increased resistivity of the ultimate layer, may account for distortion observed at long periods. Two-dimensional test models show that the conducting layer in the area of Villarrica volcano may be an anomalous heated layer surrounded by rocks of higher resistivity of about 2 × 10 3 ω m. These features correspond to the interaction with a subsiding oceanic lithosphere resulting in a complex thermal structure and perturbed resistivity distribution in transition zones of the Pacific type such as Chile, and to the existence of a megafault and a system of fractures in the sounding area. These facts make it difficult to determine the conductance of the electrical asthenosphere. The parameters of the model structure correlate well with geophysical and geochemical results obtained in the area by other workers. Gravity studies indicate a maximum crustal thickness of about 37 km, which implies a non-full compensation according to the Airy hypothesis. The morphology of the Wadati-Benioff zone clearly shows a sharp decrease of earthquake foci at 50 km depth, and a reinitiation of
Galilo, Bogdan V.; Nedelko, Sergei N.
2011-11-01
The one-loop quark contribution to the QCD effective potential for the homogeneous Abelian gluon field in the presence of an external strong electromagnetic field is evaluated. The structure of extrema of the potential as a function of the angles between chromoelectric, chromomagnetic, and electromagnetic fields is analyzed. In this setup, the electromagnetic field is considered as an external one while the gluon field represents domain structured nonperturbative gluon configurations related to the QCD vacuum in the confinement phase. Two particularly interesting gluon configurations, (anti-)self-dual and crossed orthogonal chromomagnetic and chromoelectric fields, are discussed specifically. Within this simplified framework it is shown that the strong electromagnetic fields can play a catalyzing role for a deconfinement transition. At the qualitative level, the present consideration can be seen as a highly simplified study of an impact of the electromagnetic fields generated in relativistic heavy ion collisions on the strongly interacting hadronic matter.
Blaizot, Jean-Paul; Liao, Jinfeng; Mehtar-Tani, Yacine
2016-12-01
We analyze the interplay of elastic and inelastic collisions in the thermalization of the quark-gluon plasma, using kinetic theory. Our main focus is the dynamics and equilibration of long wavelength modes.
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
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.
Propagation of cosmic rays through the atmosphere in the quark-gluon strings model
NASA Technical Reports Server (NTRS)
Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.
1985-01-01
The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.
Spatially modulated phase in the holographic description of quark-gluon plasma.
Ooguri, Hirosi; Park, Chang-Soon
2011-02-11
We present a string theory construction of a gravity dual of a spatially modulated phase. Our earlier work shows that the Chern-Simons term in the five-dimensional Maxwell theory destabilizes the Reissner-Nordström black holes in anti-de Sitter space if the Chern-Simons coupling is sufficiently high. In this Letter, we show that a similar instability is realized on the world volume of 8-branes in the Sakai-Sugimoto model in the quark-gluon plasma phase. Our result suggests a new spatially modulated phase in quark-gluon plasma when the baryon density is above 0.8Nf fm(-3) at temperature 150 MeV.
Deep learning in color: towards automated quark/gluon jet discrimination
NASA Astrophysics Data System (ADS)
Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.
2017-01-01
Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. To establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, the deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.
Classical strongly coupled quark-gluon plasma. I. Model and molecular dynamics simulations
NASA Astrophysics Data System (ADS)
Gelman, Boris A.; Shuryak, Edward V.; Zahed, Ismail
2006-10-01
We propose a model for the description of strongly interacting quarks and gluon quasiparticles at T=(1-3)Tc as a classical and nonrelativistic colored Coulomb gas. The sign and strength of the interparticle interactions are fixed by the scalar product of their classical color vectors subject to Wong's equations. The model displays a number of phases as the Coulomb coupling is increased ranging from a gas, to a liquid, to a crystal with antiferromagnetic-like color ordering. We analyze the model using molecular dynamics simulations and discuss the density-density correlator in real time. We extract pertinent decorrelation times, diffusion, and viscosity constants for all phases. The classical results when extrapolated to the strongly coupled quark-gluon plasma suggest that the phase is liquid-like, with a diffusion constant D≈0.1/T and a shear viscosity to entropy density ratio η/s≈1/3.
Deconfining Phase Transition to a Quark-Gluon Plasma in Different SU(3) Color Representations
NASA Astrophysics Data System (ADS)
Mezouar, K.; Ait El Djoudi, A.; Ghenam, L.
2016-10-01
For a statistical description of the quark gluon plasma (QGP) considering its internal symmetry, we calculate its partition function using the group theoretical projection method. We project out the partition function of a QGP consisting of gluons, massless up and down quarks, and massive strange quarks onto the singlet representation of the SU(3) color group, as well as onto the color octet and the color 27-plet representations. A comparison of these color representations is done, by studying their effects on the behavior of some thermodynamical quantities characterizing the mixed hadronic gas-QGP system undergoing a thermal deconfining phase transition on one side, and on the free energy during the formation of a QGP droplet from the hot hadronic gas on another side.
Phenomenological analysis of Higgs boson production through gluon fusion in association with jets
Greiner, Nicolas; Hoeche, Stefan; Luisoni, Gionata; Schonherr, Marek; Winter, Jan -Christopher; Yundin, Valery
2016-01-27
We present a detailed phenomenological analysis of the production of a Standard Model Higgs boson in association with up to three jets. We consider the gluon fusion channel using an effective theory in the large top-quark mass limit. Higgs boson production in gluon fusion constitutes an irreducible background to the vector boson fusion (VBF) process; hence the precise knowledge of its characteristics is a prerequisite for any measurement in the VBF channel. The calculation is carried out at next-to-leading order (NLO) in QCD in a fully automated way by combining the two programs GoS_{AM} and SHERPA. We present numerical results for a large variety of observables for both standard cuts and VBF selection cuts.
Phenomenological analysis of Higgs boson production through gluon fusion in association with jets
Greiner, Nicolas; Hoeche, Stefan; Luisoni, Gionata; ...
2016-01-27
We present a detailed phenomenological analysis of the production of a Standard Model Higgs boson in association with up to three jets. We consider the gluon fusion channel using an effective theory in the large top-quark mass limit. Higgs boson production in gluon fusion constitutes an irreducible background to the vector boson fusion (VBF) process; hence the precise knowledge of its characteristics is a prerequisite for any measurement in the VBF channel. The calculation is carried out at next-to-leading order (NLO) in QCD in a fully automated way by combining the two programs GoSAM and SHERPA. We present numerical resultsmore » for a large variety of observables for both standard cuts and VBF selection cuts.« less
Searching for gluon number fluctuations effects in eA collisions
Kugeratski, M. S.; Gonçalves, V. P.; Santana Amaral, J. T. de
2014-11-11
We propose to investigate the gluon number fluctuations effects in deep inelastic electron-ion scattering at high energies. We estimate the nuclear structure function F{sub 2}{sup A}(x,Q{sup 2}), as well the longitudinal and charm contributions, using a generalization for nuclear targets of the Golec-Biernat-Wusthoff (GBW) model which describes the electron proton HERA data. Here we consider that the nucleus at high energies acts as an amplifier of the physics of high parton densities. For a first investigation we study the scattering with Ca and Pb nuclei. Our preliminary results predict that the effects of gluon number fluctuations are small in the region of the future electron ion collider.
Evolution of collectivity as a signal of quark gluon plasma formation in heavy ion collisions
Mohanty, Payal; Alam, Jan-e; Mohanty, Bedangadas
2011-08-15
A measurement for studying the mass dependence of dilepton interferometry in relativistic heavy-ion collision experiments as a tool to characterize the quark gluon phase is proposed. In calculations involving dileptons, we show that the mass dependence of radii extracted from the virtual photon (dilepton) interferometry provide access to the development of collective flow with time. It is argued that the nonmonotonic variation of Hanbury Brown-Twiss radii with invariant mass of the lepton pairs signals the formation of quark gluon plasma in heavy ion collisions. Our proposal of experimentally measuring the ratio, R{sub out}/R{sub side} for dileptons can be used to estimate the average lifetimes of the partonic as well as the hadronic phases.
Anti pp searches for quark-gluon plasma at TeV I
Turkot, F.
1986-06-01
Three experiments that have been approved to run at TeV I are discussed from the viewpoint of their capability to search for evidence of the QCD phase transition in proton-antiproton collisions at 1.6 TeV. One of these experiments, E-735, was proposed as a dedicated search for quark-gluon plasma effects with a detector designed to study large total E/sub T/, low P/sub T/ individual particles. The other two, E-741 (CDF) and E-740 (DO), embody general purpose four-pi detectors designed primarily to study the physics of W and Z bosons and other large P/sub T/ phenomena. The detectors and their quark-gluon plasma signals are compared. 8 refs., 6 figs., 4 tabs. (LEW)
From quarks and gluons to hadronic matter: A bridge too far?
NASA Astrophysics Data System (ADS)
In the third edition of the QCD-TNT workshop the traditional focus of the last two editions (that is gaining a firmer grasp on the infrared behavior of the QCD Green's functions) will be slightly shifted towards attempts to implement the transition from the fundamental (quarks and gluons) to the effective (mesons and hadrons) degrees of freedom. So in addition to the traditional QCD-TNT themes (e.g., confinement, gluon mass generation, lattice simulations in different gauges, QCD at finite temperature and density) we plan to have more phenomenologically oriented topics (e.g., experimental reviews, determination of form factors from first principle, construction of Bethe-Salpeter kernels). In addition, a special session will be dedicated to review talks, summarizing the state-of-the-art, as well as highlighting the future perspectives, of simulating non-Abelian gauge fields using ultracold neutral atoms trapped in optical lattices, and other systems.
Next-to-leading order static gluon self-energy for anisotropic plasmas
Carrington, M. E.; Rebhan, A.
2009-01-15
In this paper the structure of the next-to-leading order static gluon self-energy for an anisotropic plasma is investigated in the limit of a small momentum space anisotropy. Using the Ward identities for the static hard-loop (HL) gluon polarization tensor and the (nontrivial) static HL vertices, we derive a comparatively compact form for the complete next-to-leading order correction to the structure function containing the spacelike pole associated with magnetic instabilities. On the basis of a calculation without HL vertices, it has been conjectured that the imaginary part of this structure function is nonzero, rendering the spacelike poles integrable. We show that there are both positive and negative contributions when HL vertices are included, highlighting the necessity of a complete numerical evaluation, for which the present work provides the basis.
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.
Production of a KK-graviton and a vector boson in ADD model via gluon fusion
NASA Astrophysics Data System (ADS)
Shivaji, Ambresh; Ravindran, V.; Agrawal, Pankaj
2012-02-01
In the models with large extra-dimensions, we examine the production of a vector boson (γ/ Z) in association with the Kaluza-Klein (KK) modes of the graviton via gluon fusion. At the leading order, the process takes place through quark-loop box and triangle diagrams and it is ultraviolate finite. We report the results for the LHC. We also discuss the issues of anomaly and decoupling of heavy quarks in the amplitude.
A New Approach for Single Transverse-Spin Asymmetries from Twist-3 Soft-Gluon Mechanism
Koike, Yuji; Tanaka, Kazuhiro
2007-06-13
A dominant QCD mechanism for the single transverse-spin asymmetry in hard processes is induced by the twist-3 quark-gluon correlations inside nucleon, combined with the soft-gluonic poles to produce the interfering phase for the associated partonic hard scattering. It is shown that the corresponding interfering amplitude can be calculated entirely in terms of the partonic Born cross section which participates in the twist-2 cross section formula for the spin-averaged process.
Event-by-event hydrodynamics: A better tool to study the Quark-Gluon plasma
Grassi, Frederique
2013-03-25
Hydrodynamics has been established as a good tool to describe many data from relativistic heavyion collisions performed at RHIC and LHC. More recently, it has become clear that it is necessary to use event-by-event hydrodynamics (i.e. describe each collision individually using hydrodynamics), an approach first developed in Brazil. In this paper, I review which data require the use of event-by-event hydrodynamics and what more we may learn on the Quark-Gluon Plasma with this.
Influence of the nonperturbative quark-gluon vertex on the meson and baryon spectrum
Williams, Richard; Sanchis-Alepuz, Hèlios
2016-01-22
We present a calculation of the Hadron spectrum in the Dyson-Schwinger/Bethe-Salpeter approach to continuum QCD. A sophisticated truncation featuring all covariant structures of the quark-gluon vertex, with its inherent flavour dependence, is employed in a framework that preserves the dynamics of chiral symmetry breaking. The study is suggestive as to the relevance of additional resonant and non-resonant two- and three-body contributions.
A measurement of the gluon splitting rate into /cc¯ pairs in hadronic Z decays
NASA Astrophysics Data System (ADS)
ALEPH Collaboration; Heister, A.; Schael, S.; Barate, R.; Brunelière, R.; de Bonis, I.; Decamp, D.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocmé, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmüller, O.; Cattaneo, M.; Cerutti, F.; Clerbaux, B.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Hansen, J. B.; Harvey, J.; Hutchcroft, D. E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Sguazzoni, G.; Tejessy, W.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J. M.; Perret, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Kraan, A.; Nilsson, B. S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Swynghedauw, M.; Tanaka, R.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G. P.; Passalacqua, L.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Thompson, A. S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Leibenguth, G.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P. J.; Girone, M.; Hill, R. D.; Marinelli, N.; Nowell, J.; Rutherford, S. A.; Sedgbeer, J. K.; Thompson, J. C.; White, R.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Clarke, D. P.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Smizanska, M.; van der Aa, O.; Delaere, C.; Lemaitre, V.; Blumenschein, U.; Hölldorfer, F.; Jakobs, K.; Kayser, F.; Kleinknecht, K.; Müller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Männer, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Awunor, O.; Blair, G. A.; Cowan, G.; Garcia-Bellido, A.; Green, M. G.; Jones, L. T.; Medcalf, T.; Misiejuk, A.; Strong, J. A.; Teixeira-Dias, P.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Ward, J. J.; Bloch-Devaux, B.; Boumediene, D.; Colas, P.; Fabbro, B.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, B.; Konstantinidis, N.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S. R.; Berkelman, K.; Cranmer, K.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A.; Nielsen, J.; Pan, Y. B.; von Wimmersperg-Toeller, J. H.; Wiedenmann, W.; Wu, J.; Wu, Sau Lan; Wu, X.; Zobernig, G.; Dissertori, G.
2003-05-01
The rate of gluon splitting into /cc¯ pairs in hadronic Z decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is gcc¯=(3.26+/-0.23(stat)+/-0.42(syst))%.
Describing the strongly interacting quark-gluon plasma through the Friedberg-Lee model
NASA Astrophysics Data System (ADS)
Shu, Song; Li, Jia-Rong
2010-10-01
The Friedberg-Lee (FL) model is studied at finite temperature and density. The soliton solutions of the FL model in the deconfinement phase transition are solved and thoroughly discussed for certain boundary conditions. We indicate that the solitons before and after the deconfinement have different physical meanings: the soliton before deconfinement represents hadrons, while the soliton after the deconfinement represents the bound state of quarks which leads to a strongly interacting quark-gluon plasma phase. The corresponding phase diagram is given.
Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
Hrayr Matevosyan; Anthony Thomas; Peter Tandy
2007-04-01
We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. With the more consistent vertex used here, the error in ladder-rainbow truncation for vector mesons is never more than 10% as the current quark mass is varied from the u/d region to the b region.
Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
Matevosyan, Hrayr H.; Thomas, Anthony W.; Tandy, Peter C.
2007-04-15
We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light-quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three-gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. Within the current model, the more consistent dressed vertex limits the ladder-rainbow truncation error for vector mesons to be never more than 10% as the current quark mass is varied from the u/d region to the b region.
Confinement of quarks and valence gluons in SU( N) Yang-Mills-Higgs models
NASA Astrophysics Data System (ADS)
Oxman, L. E.
2013-03-01
In this work, we analyze a class of Yang-Mills models containing adjoint Higgs fields, with SU( N) symmetry spontaneously broken down to Z( N), showing they contain center vortices, Y-junctions formed by them, and junctions where different center vortices are smoothly interpolated by monopole-like configurations. In the context of dual superconductors, these objects represent different states of the gluon field. Center vortices confine quarks to form normal hadron states. The interpolating monopole, which in our model cannot exist as an isolated configuration, is identified with a confined valence gluon. A junction containing a monopole can bind quarks in a color nonsinglet state to form an overall neutral object, identified with a hybrid hadron. These states, formed by quarks bound to a valence gluon, are allowed by QCD, and current experimental collaborations are aimed at identifying them. Finally, considering the general version of the model, based on a compact simple gauge group G, the picture is completed with a heuristic discussion about why it would be natural using as G the dual of the chromoelectric gauge group G e, and external pointlike monopoles to represent the mesonic and baryonic Wilson loops.
Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
NASA Astrophysics Data System (ADS)
Matevosyan, Hrayr H.; Thomas, Anthony W.; Tandy, Peter C.
2007-04-01
We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light-quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three-gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. Within the current model, the more consistent dressed vertex limits the ladder-rainbow truncation error for vector mesons to be never more than 10% as the current quark mass is varied from the u/d region to the b region.
Triple gluon coupling, Adler-Bell-Jackiw anomaly, and polarized deep inelastic scattering
Lam, C.S.; Li, B.A.
1980-05-01
An unusual effect of triple gluon coupling and the Adler-Bell-Jackiw anomaly on the flavor singlet part of the polaried deep inelastic scattering structure function ..nu..G/sub 1/(Q/sup 2/,x) are discussed. Namely, the x-integral I/sub S/(Q/sup 2/) of this function is Q/sup 2/-independent both in parton model and leading logarithm calculations, but the first order nonleading logarithm calculation produces a term growing like (-lnlnQ/sup 2/), dominating over the parton model contributions at large Q/sup 2/. The detection of this unusual term will amount to an experimental confirmation of the existence of triple gluon coupling and the Adler-Bell-Jackiw anomaly. Technically, this term comes from a new axial vector gluon operator which is introduced in the Wilson expansion. Other results of this paper include a discussion of mass-sensitive and mass-insensitive structure functions and the derivation of the expression for, and the relations between, some of these structure functions.
NASA Astrophysics Data System (ADS)
Snihur, Robert Michael
2000-12-01
This thesis presents some of the first experimental results of the k⊥ jet algorithm at a hadron collider. Gluon jets dominate the final state of proton-antiproton (pp¯) collisions at high center-of- mass energies (
Obtaining and maintaining funding
Beverly Hartline
1996-04-01
Obtaining and maintaining funding is important for individuals, groups, institutions, and fields. This challenge is easier during times of abundant and growing resources than it is now, when funding is tight and shrinking. Thus, to obtain and maintain funding will require: maintaining healthy funding levels for all of science; maintaining healthy funding levels for the field(s) you work in; and competing successfully for the available funds. Everyone should pay attention to the overall prospects for science funding and dedicate some effort to working with others to grow the constituency for science. Public support is likely an important prerequisite for keeping future science budgets high. In this context, researchers should share with society at large the benefits of their research, so that taxpayers can see and appreciate some return from the federal investment in science. Assuming this effort is successful, and there continue to be government and private organizations with substantial resources to invest in research, what can the individual investigator do to improve her chances? She can be clear about her goal(s) and carefully plan her effort to make maximum progress for minimum resources, especially early in her career while she is establishing a solid professional reputation. Specific useful strategies include: brainstorm funding options and select the most promising one(s); be persistent but flexible, responsive to new information and changing circumstances; provide value and assistance to prospective funding sources both before and after receiving funding; know the funding agents and what their goals are, they are the customers; promise a lot and always deliver more; build partnerships and collaboration to leverage interest and resources; and develop capabilities and ideas with a promising, irresistible future. There is no guarantee of success. For the best chances, consistently contribute positively and productively in all your efforts, and continue to
Lund, Flemming; Petersen, Per Hyltoft; Fraser, Callum G; Sölétormos, György
2016-11-01
Background Reference change values provide objective tools to assess the significance of a change in two consecutive results for a biomarker from an individual. The reference change value calculation is based on the assumption that within-subject biological variation has random fluctuation around a homeostatic set point that follows a normal (Gaussian) distribution. This set point (or baseline in steady-state) should be estimated from a set of previous samples, but, in practice, decisions based on reference change value are often based on only two consecutive results. The original reference change value was based on standard deviations according to the assumption of normality, but was soon changed to coefficients of variation (CV) in the formula (reference change value = ± Z ċ 2(½) ċ CV). Z is being dependent on the desired probability of significance, which also defines the percentages of false-positive results. The aim of this study was to investigate false-positive results using five different published methods for calculation of reference change value. Methods The five reference change value methods were examined using normally and ln-normally distributed simulated data. Results One method performed best in approaching the theoretical false-positive percentages on normally distributed data and another method performed best on ln-normally distributed data. The commonly used reference change value method based on two results (without use of estimated set point) performed worst both on normally distributed and ln-normally distributed data. Conclusions The optimal choice of method to calculate reference change value limits requires knowledge of the distribution of data (normal or ln-normal) and, if possible, knowledge of the homeostatic set point.
NASA Technical Reports Server (NTRS)
Butler, Thomas G.
1990-01-01
In modeling a complex structure the researcher was faced with a component that would have logical appeal if it were modeled as a beam. The structure was a mast of a robot controlled gantry crane. The structure up to this point already had a large number of degrees of freedom, so the idea of conserving grid points by modeling the mast as a beam was attractive. The researcher decided to make a separate problem of of the mast and model it in three dimensions with plates, then extract the equivalent beam properties by setting up the loading to simulate beam-like deformation and constraints. The results could then be used to represent the mast as a beam in the full model. A comparison was made of properties derived from models of different constraints versus manual calculations. The researcher shows that the three-dimensional model is ineffective in trying to conform to the requirements of an equivalent beam representation. If a full 3-D plate model were used in the complete representation of the crane structure, good results would be obtained. Since the attempt is to economize on the size of the model, a better way to achieve the same results is to use substructuring and condense the mast to equivalent end boundary and intermediate mass points.
Exploring the Quark-Gluon Content of Hadrons: From Mesons to Nuclear Matter
Matevosyan, Hrayr
2007-08-01
Even though Quantum Chromodynamics (QCD) was formulated over three decades ago, it poses enormous challenges for describing the properties of hadrons from the underlying quark-gluon degrees of freedom. Moreover, the problem of describing the nuclear force from its quark-gluon origin is still open. While a direct solution of QCD to describe the hadrons and nuclear force is not possible at this time, we explore a variety of developed approaches ranging from phenomenology to first principle calculations at one or other level of approximation in linking the nuclear force to QCD. The Dyson Schwinger formulation (DSE) of coupled integral equations for the QCD Green’s functions allows a non-perturbative approach to describe hadronic properties, starting from the level of QCD n-point functions. A significant approximation in this method is the employment of a finite truncation of the system of DSEs, that might distort the physical picture. In this work we explore the effects of including a more complete truncation of the quark-gluon vertex function on the resulting solutions for the quark 2-point functions as well as the pseudoscalar and vector meson masses. The exploration showed strong indications of possibly large contributions from the explicit inclusion of the gluon 3- and 4-point functions that are omitted in this and previous analyses. We then explore the possibility of extrapolating state of the art lattice QCD calculations of nucleon form factors to the physical regime using phenomenological models of nucleon structure. Finally, we further developed the Quark Meson Coupling model for describing atomic nuclei and nuclear matter, where the quark-gluon structure of nucleons is modeled by the MIT bag model and the nucleon many body interaction is mediated by the exchange of scalar and vector mesons. This approach allows us to formulate a fully relativistic theory, which can be expanded in the nonrelativistic limit to reproduce the well known phenomenological Skyrme
Quarks, Gluons and Color are sufficient, but are they necessary?
NASA Astrophysics Data System (ADS)
Bartlett, David
2016-03-01
John Stewart Bell died in 1990. Two experiments in the last year have made one appreciate Bell's support for instantaneous action at a distance (``quantum spookiness'') and his disdain for ``hidden variables''. R. Hanson et al constructed an entangled state with electrons in two labs 1.3 km apart. At NIST, C.W. Clark et al gave a free neutron orbital angular momentum. The neutron joins the electron and photon as particles that can be given L. Who knows how the up and down quarks enjoyed this experience. Quarks are the most obvious hidden variable in physics. No person has isolated even one. Consequently, the standard model features ``Quark Confinement''. Unfortunately confinement complicates the comparison of QED and QCD.. The alternatives to quarks are scattering lengths, resonances, octets, decuplets, and singlets. This talk will elucidate some of the pre LHC tensions in the standard model. Why is strangeonium qualitatively different from charmonium and bottomonium . Why does the process γ + γ --> η + η (Belle 2010) have a resonance at just the mass of the J/psi, but with a forward & backward peaked angular distribution that contrasts with the isotropy of the J/psi(1S)(1974)? What is needed to show that it is really the off-diagonal elements in the K-mass matrix that are responsible for CP violation (CPLEAR 1999). My colleague John Cumalat MAY submit something. If so, please call either him (303) 492-8604 or me (303) 492-6960.
The four-loop six-gluon NMHV ratio function
Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.
2016-01-11
We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N = 4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q^{-} differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result against multi- Regge predictions at NNLL and N^{3}LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We also study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. Furthermore, we provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.
The four-loop six-gluon NMHV ratio function
Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.
2016-01-11
We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N=4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q¯ differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result against multi-Regge predictions at NNLL and N^{3}LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. As a result, we also provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.
The four-loop six-gluon NMHV ratio function
Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.
2016-01-11
We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N=4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q¯ differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result againstmore » multi-Regge predictions at NNLL and N3LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. As a result, we also provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.« less
Hyperfine meson splittings: chiral symmetry versus transverse gluon exchange
Felipe J. Llanes-Estrada; Stephen R. Cotanch; Adam P. Szczepaniak; Eric S. Swanson
2004-02-01
Meson spin splittings are examined within an effective Coulomb gauge QCD Hamiltonian incorporating chiral symmetry and a transverse hyperfine interaction necessary for heavy quarks. For light and heavy quarkonium systems the pseudoscalar-vector meson spectrum is generated by approximate BCS-RPA diagonalizations. This relativistic formulation includes both S and D waves for the vector mesons which generates a set of coupled integral equations. A smooth transition from the heavy to the light quark regime is found with chiral symmetry dominating the /pi-/rho mass difference. A good, consistent description of the observed meson spin splittings and chiral quantities, such as the quark condensate and the /pi mass, is obtained. Similar comparisons with TDA diagonalizations, which violate chiral symmetry, are deficient for light pseudoscalar mesons indicating the need to simultaneously include both chiral symmetry and a hyperfine interaction. The /eta{sub b} mass is predicted to be around 9400 MeV consistent with other theoretical expectations and above the unconfirmed 9300 MeV candidate. Finally, for comparison with lattice results, the J reliability parameter is also evaluated.
NASA Astrophysics Data System (ADS)
Lacey, Roy A.; Reynolds, D.; Taranenko, A.; Ajitanand, N. N.; Alexander, J. M.; Liu, Fu-Hu; Gu, Yi; Mwai, A.
2016-10-01
It is shown that the acoustic scaling patterns of anisotropic flow for different event shapes at a fixed collision centrality (shape-engineered events), provide robust constraints for the event-by-event fluctuations in the initial-state density distribution from ultrarelativistic heavy ion collisions. The empirical scaling parameters also provide a dual-path method for extracting the specific shear viscosity {(η /s)}{QGP} of the quark-gluon plasma (QGP) produced in these collisions. A calibration of these scaling parameters via detailed viscous hydrodynamical model calculations, gives {(η /s)}{QGP} estimates for the plasma produced in collisions of Au + Au (\\sqrt{{s}{NN}}=0.2 {TeV}) and Pb + Pb (\\sqrt{{s}{NN}}=2.76 {TeV}). The estimates are insensitive to the initial-state geometry models considered.
How do quarks and gluons lose energy in the QGP?
Tannenbaum, M. J.
2015-03-10
multiplicity or transverse energy production in p-p collisions–soft particles, with ρT < 2 GeV/c, predominate. Thus an apparent hard scattering component for A+A multiplicity distributions based on a popular formula, dNAAch/dη = [(1 - x) (Npart)dNppch/dη2 + x (NcolldNppch/dη], seems to be an unphysical way to understand the deviation from Npart scaling. Based on recent p-p and d+A measurements, a more physical way is presented along with several other stimulating results and ideas from recent d+Au (p+Pb) measurements.« less
How do quarks and gluons lose energy in the QGP?
Tannenbaum, M. J.
2015-03-10
k_{T}-effect. Another issue well known from experiments at the CERN ISR, SpS and SpS collider is that parton-parton hard-collisions make negligible contribution to multiplicity or transverse energy production in p-p collisions–soft particles, with ρ_{T} < 2 GeV/c, predominate. Thus an apparent hard scattering component for A+A multiplicity distributions based on a popular formula, dN^{AA}_{ch}/dη = [(1 - x) (N_{part})dN^{pp}_{ch}/dη2 + x (N_{coll}dN^{pp}_{ch}/dη], seems to be an unphysical way to understand the deviation from N_{part} scaling. Based on recent p-p and d+A measurements, a more physical way is presented along with several other stimulating results and ideas from recent d+Au (p+Pb) measurements.
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A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb[Formula: see text] of proton-proton collision data at [Formula: see text] [Formula: see text] collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of [Formula: see text] 10-20 %. In data, light-quark jets can be tagged with an efficiency of [Formula: see text] while achieving a gluon-jet mis-tag rate of [Formula: see text] in a [Formula: see text] range between [Formula: see text] and [Formula: see text] for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6 Monte Carlo simulation, where gluon-jet mis-tag rates of 10 % can be reached for a 50 % selection efficiency of light-quark jets using the same jet properties.
NASA Astrophysics Data System (ADS)
Gómez-Rocha, M.; Hilger, T.; Krassnigg, A.
2016-04-01
We extend earlier investigations of heavy-light pseudoscalar mesons to the vector case, using a simple model in the context of the Dyson-Schwinger-Bethe-Salpeter approach. We investigate the effects of a dressed quark-gluon vertex in a systematic fashion and illustrate and attempt to quantify corrections beyond the phenomenologically very useful and successful rainbow-ladder truncation. In particular we investigate the dressed quark-photon vertex in such a setup and make a prediction for the experimentally as yet unknown mass of the Bc* , which we obtain at 6.334 GeV well in line with predictions from other approaches. Furthermore, we combine a comprehensive set of results from the theoretical literature. The theoretical average for the mass of the Bc* meson is 6.336 ±0.002 GeV .
Where are we in the search for the Quark Gluon Plasma?
Ullrich, Thomas
2006-02-08
The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory was completed in 1999, with the first data-taking runs in the summer of 2000. Since then the measurements at RHIC have yielded a wealth of data from four independent detectors: BRAHMS, PHENIX, PHOBOS, and STAR. For the first time, collisions of heavy nuclei have been carried out with colliding-beam energies that have previously been accessible only to high-energy physics experiments. It is at these high energies that the predictions of QCD come into play and new phenomena are sought that may illuminate our view of the basic structure of matter.The RHIC experiments have recorded data from collisions of gold nuclei from {radical}(S{sub NN}) = 19 GeV up to the highest energy of 200 GeV, as well as reference data in proton-proton and deuteron-gold collisions. These collisions result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision.The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high density and temperature. This medium allows for the predictions of QCD to be tested, and new phenomena explored, under conditions where the relevant degrees of freedom, over nuclear volumes, are expected to be those of quarks and gluons, rather than of hadrons. This is the realm of the quark gluon plasma.However, detailed analyses of the data also make it clear that this hot, dense medium has properties that are surprising, and not yet fully understood in terms of the early expectations for the quark gluon plasma. In this paper I review the major findings of the RHIC experiments to date and discuss the current understanding of the state of matter created.
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.
Yoctosecond metrology through Hanbury Brown-Twiss correlations from a quark-gluon plasma.
Ipp, Andreas; Somkuti, Peter
2012-11-09
Expansion dynamics at the yoctosecond time scale affect the evolution of the quark gluon plasma (QGP) created in heavy ion collisions. We show how these dynamics are accessible through Hanbury Brown-Twiss (HBT) intensity interferometry of direct photons emitted from the interior of the QGP. A detector placed close to the beam axis is particularly sensitive to early polar momentum anisotropies of the QGP. Observing a modification of the HBT signal at the proposed FoCal detector of the LHC ALICE experiment would allow us to measure the isotropization time of the plasma and could provide first experimental evidence for photon double pulses at the yoctosecond time scale.
Color path-integral Monte Carlo simulations of quark-gluon plasma
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Fortov, V. E.; Levashov, P. R.
2012-02-01
Thermodynamic properties of a strongly coupled quark-gluon plasma (QGP) of constituent quasiparticles are studied by a color path-integral Monte Carlo simulations (CPIMC). For our simulations we have presented QGP partition function in the form of color path integral with new relativistic measure instead of Gaussian one used in Feynman and Wiener path integrals. For integration over color variable we have also developed procedure of sampling color variables according to the group SU(3) Haar measure. It is shown that this method is able to reproduce the available quantum lattice chromodynamics (QCD) data.
Jet flavor tomography of quark gluon plasmas at RHIC and LHC.
Buzzatti, Alessandro; Gyulassy, Miklos
2012-01-13
A new Monte Carlo model of jet quenching in nuclear collisions, CUJET1.0, is applied to predict the jet flavor dependence of the nuclear modification factor for fragments f=π,D,B,e(-) from quenched jet flavors g,u,c,b in central collisions at RHIC and LHC. The nuclear modification factors for different flavors are predicted to exhibit a novel level crossing pattern over a transverse momentum range 5
gluon plasmas.
Measurement of the multiplicity of gluons splitting to bottom quark pairs in hadronic Z0 decays
NASA Astrophysics Data System (ADS)
Abreu, P.; Adam, W.; Adye, T.; Ajinenko, I.; Alekseev, G. D.; Alemany, R.; Allport, P. P.; Almehed, S.; Amaldi, U.; Amato, S.; Andersson, P.; Andreazza, A.; Antilogus, P.; Apel, W.-D.; Åsman, B.; Augustin, J.-E.; Augustinus, A.; Baillon, P.; Bambade, P.; Barao, F.; Barbi, M.; Barbiellini, G.; Bardin, D. Y.; Barker, G.; Baroncelli, A.; Barring, O.; Bates, M. J.; Battaglia, M.; Baubillier, M.; Baudot, J.; Becks, K.-H.; Begalli, M.; Beilliere, P.; Belokopytov, Yu.; Belous, K.; Benvenuti, A. C.; Berggren, M.; Bertini, D.; Bertrand, D.; Besancon, M.; Bianchi, F.; Bigi, M.; Bilenky, M. S.; Billoir, P.; Bizouard, M.-A.; Bloch, D.; Blume, M.; Bonesini, M.; Bonivento, W.; Booth, P. S. L.; Borgland, A. W.; Borisov, G.; Bosio, C.; Botner, O.; Boudinov, E.; Bouquet, B.; Bourdarios, C.; Bowcock, T. J. V.; Bozzo, M.; Branchini, P.; Brand, K. D.; Brenke, T.; Brenner, R. A.; Bricman, C.; Brown, R. C. A.; Bruckman, P.; Brunet, J.-M.; Bugge, L.; Buran, T.; Burgsmueller, T.; Buschmann, P.; Cabrera, S.; Caccia, M.; Calvi, M.; Rozas, A. J. Camacho; Camporesi, T.; Canale, V.; Canepa, M.; Cao, F.; Carena, F.; Carroll, L.; Caso, C.; Gimenez, M. V. Castillo; Cattai, A.; Cavallo, F. R.; Chabaud, V.; Charpentier, Ph.; Chaussard, L.; Checchia, P.; Chelkov, G. A.; Chen, M.; Chierici, R.; Chliapnikov, P.; Chochula, P.; Chorowicz, V.; Cindro, V.; Collins, P.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Cowell, J.-H.; Crawley, H. B.; Crennell, D.; Crosetti, G.; Maestro, J. Cuevas; Czellar, S.; Dahm, J.; Dalmagne, B.; Dam, M.; Damgaard, G.; Dauncey, P. D.; Davenport, M.; da Silva, W.; Deghorain, A.; della Ricca, G.; Delpierre, P.; Demaria, N.; de Angelis, A.; de Boer, W.; de Brabandere, S.; de Clercq, C.; de La Vaissiere, C.; de Lotto, B.; de Min, A.; de Paula, L.; Dijkstra, H.; di Ciaccio, L.; di Diodato, A.; Djannati, A.; Dolbeau, J.; Doroba, K.; Dracos, M.; Drees, J.; Drees, K.-A.; Dris, M.; Durand, J.-D.; Edsall, D.; Ehret, R.; Eigen, G.; Ekelof, T.; Ekspong, G.; Elsing, M.; Engel, J.-P.; Erzen, B.; Espirito Santo, M.; Falk, E.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Ferrari, P.; Ferrer, A.; Fichet, S.; Filippas, T. A.; Firestone, A.; Fischer, P.-A.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Formenti, F.; Franek, B.; Frodesen, A. G.; Fruhwirth, R.; Fulda-Quenzer, F.; Fuster, J.; Galloni, A.; Gamba, D.; Gandelman, M.; Garcia, C.; Garcia, J.; Gaspar, C.; Gasparini, U.; Gavillet, Ph.; Gazis, E. N.; Gele, D.; Gerber, J.-P.; Gerdyukov, L.; Gokieli, R.; Golob, B.; Goncalves, P.; Gopal, G.; Gorn, L.; Gorski, M.; Gouz, Yu.; Gracco, V.; Graziani, E.; Green, C.; Grefrath, A.; Gris, P.; Grosdidier, G.; Grzelak, K.; Gumenyuk, S.; Gunther, M.; Guy, J.; Hahn, F.; Hahn, S.; Hajduk, Z.; Hallgren, A.; Hamacher, K.; Harris, F. J.; Hedberg, V.; Henriques, R.; Hernandez, J. J.; Herquet, P.; Herr, H.; Hessing, T. L.; Heuser, J.-M.; Higon, E.; Holmgren, S.-O.; Holt, P. J.; Holthuizen, D.; Hoorelbeke, S.; Houlden, M.; Hrubec, J.; Huet, K.; Hultqvist, K.; Jackson, J. N.; Jacobsson, R.; Jalocha, P.; Janik, R.; Jarlskog, Ch.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Johansson, E. K.; Jonsson, L.; Jonsson, P.; Joram, C.; Juillot, P.; Kaiser, M.; Kapusta, F.; Karafasoulis, K.; Karlsson, M.; Katsanevas, S.; Katsoufis, E. C.; Keranen, R.; Khokhlov, Yu.; Khomenko, B. A.; Khovanski, N. N.; King, B.; Kjaer, N. J.; Klapp, O.; Klein, H.; Kluit, P.; Knoblauch, D.; Kokkinias, P.; Konopliannikov, A.; Koratzinos, M.; Korcyl, K.; Kostioukhine, V.; Kourkoumelis, C.; Kouznetsov, O.; Krammer, M.; Kreuter, C.; Kronkvist, I.; Krstic, J.; Krumstein, Z.; Krupinski, W.; Kubinec, P.; Kucewicz, W.; Kurvinen, K.; Lacasta, C.; Laktineh, I.; Lamsa, J. W.; Lanceri, L.; Lane, D. W.; Langefeld, P.; Laugier, J.-P.; Lauhakangas, R.; Leder, G.; Ledroit, F.; Lefebure, V.; Legan, C. K.; Leisos, A.; Leitner, R.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Libby, J.; Liko, D.; Lipniacka, A.; Lippi, I.; Loerstad, B.; Loken, J. G.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Maehlum, G.; Mahon, J. R.; Maio, A.; Malmgren, T. G. M.; Malychev, V.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Martinez-Vidal, F.; Garcia, S. Marti I.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazzucato, M.; Mc Cubbin, M.; Mc Kay, R.; Mc Nulty, R.; Medbo, J.; Meroni, C.; Meyer, S.; Meyer, W. T.; Michelotto, M.; Migliore, E.; Mirabito, L.; Mitaroff, W. A.; Mjoernmark, U.; Moa, T.; Moeller, R.; Moenig, K.; Monge, M. R.; Morettini, P.; Mueller, H.; Muenich, K.; Mulders, M.; Mundim, L. M.; Murray, W. J.; Muryn, B.; Myatt, G.; Myklebust, T.; Naraghi, F.; Navarria, F. L.; Navas, S.; Nawrocki, K.; Negri, P.; Nemecek, S.; Neumann, W.; Neumeister, N.; Nicolaidou, R.; Nielsen, B. S.; Nieuwenhuizen, M.; Nikolaenko, V.; Nikolenko, M.; Niss, P.; Nomerotski, A.; Normand, A.; Novak, M.; Oberschulte-Beckmann, W.; Obraztsov, V.; Olshevski, A. G.; Orava, R.; Orazi, G.; Osterberg, K.; Ouraou, A.; Paganini, P.; Paganoni, M.; Pain, R.; Palka, H.; Papadopoulou, Th. D.; Papageorgiou, K.; Pape, L.; Parkes, C.; Parodi, F.; Passeri, A.; Pegoraro, M.; Peralta, L.; Pernegger, H.; Pernicka, M.; Perrotta, A.; Petridou, C.; Petrolini, A.; Phillips, H. T.; Piana, G.; Pierre, F.; Pimenta, M.; Podobnik, T.; Podobrin, O.; Pol, M. E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Ragazzi, S.; Rahmani, H.; Rames, J.; Ratoff, P. N.; Read, A. L.; Reale, M.; Rebecchi, P.; Redaelli, N. G.; Regler, M.; Reid, D.; Reinhardt, R.; Renton, P. B.; Resvanis, L. K.; Richard, F.; Richardson, J.; Ridky, J.; Rinaudo, G.; Rohne, O.; Romero, A.; Ronchese, P.; Roos, L.; Rosenberg, E. I.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ruiz, A.; Rybicki, K.; Saarikko, H.; Sacquin, Y.; Sadovsky, A.; Sahr, O.; Sajot, G.; Salt, J.; Sannino, M.; Schneider, H.; Schwickerath, U.; Schyns, M. A. E.; Sciolla, G.; Scuri, F.; Seager, P.; Sedykh, Y.; Segar, A. M.; Seitz, A.; Sekulin, R.; Serbelloni, L.; Shellard, R. C.; Siegrist, P.; Silvestre, R.; Simonetto, F.; Sisakian, A. N.; Sitar, B.; Skaali, T. B.; Smadja, G.; Smirnov, N.; Smirnova, O.; Smith, G. R.; Sokolov, A.; Solovianov, O.; Sosnowski, R.; Souza-Santos, D.; Spassov, T.; Spiriti, E.; Sponholz, P.; Squarcia, S.; Stampfer, D.; Stanescu, C.; Stanic, S.; Stapnes, S.; Stavitski, I.; Stevenson, K.; Stocchi, A.; Strub, R.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Tabarelli, T.; Tavernet, J. P.; Tchikilev, O.; Tegenfeldt, F.; Terranova, F.; Thomas, J.; Tilquin, A.; Timmermans, J.; Tkatchev, L. G.; Todorov, T.; Todorova, S.; Toet, D. Z.; Tomaradze, A.; Tome, B.; Tonazzo, A.; Tortora, L.; Transtromer, G.; Treille, D.; Tristram, G.; Trombini, A.; Troncon, C.; Tsirou, A.; Turluer, M.-L.; Tyapkin, I. A.; Tyndel, M.; Tzamarias, S.; Ueberschaer, B.; Ullaland, O.; Uvarov, V.; Valenti, G.; Vallazza, E.; Velde, C. Vander; van Apeldoorn, G. W.; van Dam, P.; van Doninck, W. K.; van Eldik, J.; van Lysebetten, A.; Vassilopoulos, N.; Vegni, G.; Ventura, L.; Venus, W.; Verbeure, F.; Verlato, M.; Vertogradov, L. S.; Vilanova, D.; Vincent, P.; Vitale, L.; Vodopyanov, A. S.; Vrba, V.; Wahlen, H.; Walck, C.; Weiser, C.; Wetherell, A. M.; Wicke, D.; Wickens, J. H.; Wielers, M.; Wilkinson, G. R.; Williams, W. S. C.; Winter, M.; Witek, M.; Wlodek, T.; Yi, J.; Yip, K.; Yushchenko, O.; Zach, F.; Zaitsev, A.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zevgolatakos, E.; Zimin, N. I.; Zucchelli, G. C.; Zumerle, G.
1997-02-01
An inclusive measurement of the average multiplicity of bb pairs from gluons, gbb, in hadronic Z0 events collected by the DELPHI experiment at LEP, is presented. A counting technique, based on jet b-tagging in 4-jet events, has been used. Looking for secondary bottom production in events with production of any primary flavour, by requiring two b-tagged jets in well defined topological configurations, gave gbb = (0.21 +/- 0.11 (stat) +/- 0.09(syst)) %. This result was checked with a different method designed to select events with four b quarks in the final state. Agreement within the errors was found.
Ghost-gluon running coupling, power corrections, and the determination of {lambda}{sub MS}
Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; De Soto, F.; Rodriguez-Quintero, J.
2009-01-01
We compute a formula including operator-product expansion power corrections to describe the running of a QCD coupling nonperturbatively defined through the ghost and gluon dressing functions. This turns out to be rather accurate. We propose the 'plateau' procedure to compute {lambda}{sub MS} from the lattice computation of the running coupling constant. We show a good agreement between the different methods which have been used to estimate {lambda}{sub MS}{sup N{sub f}}{sup =0}. We argue that {lambda}{sub MS} or the strong coupling constant computed with different lattice spacings may be used to estimate the lattice spacing ratio.
Modeling strongly coupled quark gluon plasmas: hydro vs transport vs general relativity
NASA Astrophysics Data System (ADS)
Gyulassy, Miklos
2008-04-01
The discovery of near perfect fluid flow and very high jet opacity in nuclear collisions at 200 AGeV at RHIC/BNL have challenged traditional weak coupling perturbative QCD modeling of quark gluon plasmas. A critical assessment of current theoretical uncertainties facing competing approaches based on relativistic hydrodynamics, quasi-parton transport dynamics, and novel string theory inspired general relativity modeling will be presented. Special focus will be on identified (charm and bottom) heavy quark jets that will serve as powerful probes in upcoming RHIC and LHC experiments to better constrain the initial conditions as well as energy loss mechanisms leading to rapid equilibration in ultra-relativistic nuclear collisions.
A Secular Quark Gluon Plasma Phase Preceding Black HoleFormation
Mitra, Abhas; Glendenning, Norman K.
2006-01-13
As spherical collapse of very massive stars would tend to the formation of Black Holes with an Event Horion having a gravitational red-shift of z = {infinity}, the pressure of gravitationally trapped radiation would increase as {approx} (1 + z){sup 2}. Consequently catastrophic collapse must change into a secular collapse as the radioactive luminosity would attain its Eddington value. Since the local temperature of the collapsing body is found to be {approx} 250 MeV, the stellar mass Black Hole Candidates could be in this intermediate state of a hot Quark Gluon Plasma.
Search for the quark-gluon plasma (1989): The NA35 experiment at the CERN SPS
Pugh, H.G.
1989-09-01
Results from the NA35 experiment at the CERN SPS are described in the context of possible formation and identification of a quark-gluon plasma (QGP). Evidence is presented that the initial energy density and temperature are sufficient for the QGP to be produced, and that hydrodynamic flow occurs in the expansion stage. Evidence for an unexpectedly large pion source size and for enhanced strangeness production is presented, and discussed in terms of QGP formation. Plans for experiments in 1990--91 with an expanded set up are presented, and prospects for a program with Pb beams at the SPS are discussed. 39 refs., 12 figs.
Higgs boson gluon-fusion production beyond threshold in N3LO QCD
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; ...
2015-03-18
In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.
RHIC PHYSICS: THE QUARK GLUON PLASMA AND THE COLOR GLASS CONDENSATE: 4 LECTURES
MCLERRAN,L.
2003-01-01
The purpose of these lectures is to provide an introduction to the physics issues which are being studied in the RHIC heavy ion program. These center around the production of new states of matter. The Quark Gluon Plasma is thermal matter which once existed in the big bang which may be made at RHIC. The Color Glass Condensate is a universal form of matter which controls the high energy limit of strong interactions. Both such forms of matter might be produced and probed at RHIC.
Mochalski, Paweł; Unterkofler, Karl; Španěl, Patrik; Smith, David; Amann, Anton
2014-01-01
RATIONALE The reactions of NO+ with volatile organic compounds (VOCs) in Selective Reagent Ionization Time-of-Flight Mass Spectrometry (SRI-TOF-MS) reactors are relatively poorly known, inhibiting their use for trace gas analysis. The rationale for this product ion distribution study was to identify the major product ions of the reactions of NO+ ions with 13 organosulfur compounds and 2 organoselenium compounds in an SRI-TOF-MS instrument and thus to prepare the way for their analysis in exhaled breath, in skin emanations and in the headspace of urine, blood and cell and bacterial cultures. METHODS Product ion distributions have been investigated by a SRI-TOF-MS instrument at an E/N in the drift tube reactor of 130 Td for both dry air and humid air (4.9% absolute humidity) used as the matrix gas. The investigated species were five monosulfides (dimethyl sulfide, ethyl methyl sulfide, methyl propyl sulfide, allyl methyl sulfide and methyl 5-methyl-2-furyl sulfide), dimethyl disulfide, dimethyl trisulfide, thiophene, 2-methylthiophene, 3-methylthiophene, methanethiol, allyl isothiocyanate, dimethyl sulfoxide, and two selenium compounds – dimethyl selenide and dimethyl diselenide. RESULTS Charge transfer was seen to be the dominant reaction mechanism in all reactions under study forming the M+ cations. For methanethiol and allyl isothiocyanate significant fractions were also observed of the stable adduct ions NO+M, formed by ion-molecule association, and [M–H]+ ions, formed by hydride ion transfer. Several other minor product channels are seen for most reactions indicating that the nascent excited intermediate (NOM)+* adduct ions partially fragment along other channels, most commonly by the elimination of neutral CH3, CH4 and/or C2H4 species that are probably bound to an NO molecule. Humidity had little effect on the product ion distributions. CONCLUSIONS The findings of this study are of particular importance for data interpretation in studies of volatile
Subjet multiplicity of gluon and quark jets reconstructed with the k⊥ algorithm in ppbar collisions
NASA Astrophysics Data System (ADS)
Abazov, V. M.; Abbott, B.; Abdesselam, A.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Ahmed, S. N.; Alexeev, G. D.; Alton, A.; Alves, G. A.; Amos, N.; Anderson, E. W.; Arnoud, Y.; Avila, C.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Bacon, T. C.; Baden, A.; Baldin, B.; Balm, P. W.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bauer, D.; Bean, A.; Beaudette, F.; Begel, M.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Besson, A.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blekman, F.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Bos, K.; Bose, T.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buehler, M.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Canelli, F.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Cho, D. K.; Choi, S.; Chopra, S.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Crépé-Renaudin, S.; Cummings, M. A.; Cutts, D.; Davis, G. A.; Davis, K.; de, K.; de Jong, S. J.; del Signore, K.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; Doulas, S.; Ducros, Y.; Dudko, L. V.; Duensing, S.; Duflot, L.; Dugad, S. R.; Duperrin, A.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Filthaut, F.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Fox, H.; Frame, K. C.; Fu, S.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gao, M.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gilmartin, R.; Ginther, G.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Graham, G.; Grannis, P. D.; Green, J. A.; Greenlee, H.; Greenwood, Z. D.; Grinstein, S.; Groer, L.; Grünendahl, S.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinmiller, J. M.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hildreth, M. D.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Huang, Y.; Illingworth, R.; Ito, A. S.; Jaffré, M.; Jain, S.; Jesik, R.; Johns, K.; Johnson, M.; Jonckheere, A.; Jöstlein, H.; Juste, A.; Kahl, W.; Kahn, S.; Kajfasz, E.; Kalinin, A. M.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Khanov, A.; Kharchilava, A.; Kim, S. K.; Klima, B.; Knuteson, B.; Ko, W.; Kohli, J. M.; Kostritskiy, A. V.; Kotcher, J.; Kothari, B.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krivkova, P.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Kupco, A.; Kuznetsov, V. E.; Landsberg, G.; Lee, W. M.; Leflat, A.; Leggett, C.; Lehner, F.; Li, J.; Li, Q. Z.; Li, X.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Luo, C.; Maciel, A. K.; Madaras, R. J.; Malyshev, V. L.; Manankov, V.; Mao, H. S.; Marshall, T.; Martin, M. I.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mihalcea, D.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Moore, R. W.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Naumann, N. A.; Neal, H. A.; Negret, J. P.; Negroni, S.; Nunnemann, T.; O'Neil, D.; Oguri, V.; Olivier, B.; Oshima, N.; Padley, P.; Pan, L. J.; Papageorgiou, K.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, O.; Pétroff, P.; Piegaia, R.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Przybycien, M. B.; Qian, J.; Raja, R.; Rajagopalan, S.; Ramberg, E.; Rapidis, P. A.; Reay, N. W.; Reucroft, S.; Ridel, M.; Rijssenbeek, M.; Rizatdinova, F.; Rockwell, T.; Roco, M.; Royon, C.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Sabirov, B. M.; Sajot, G.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sen, N.; Shabalina, E.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Simak, V.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Song, Y.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Soustruznik, K.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stone, A.; Stoyanova, D. A.; Strang, M. A.; Strauss, M.; Strovink, M.; Stutte, L.; Sznajder, A.; Talby, M.; Taylor, W.; Tentindo-Repond, S.; Tripathi, S. M.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; Vaniev, V.; van Kooten, R.; Varelas, N.; Vertogradov, L. S.; Villeneuve-Seguier, F.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, H.; Wang, Z.-M.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Whiteson, D.; Wightman, J. A.; Wijngaarden, D. A.; Willis, S.; Wimpenny, S. J.; Womersley, J.; Wood, D. R.; Xu, Q.; Yamada, R.; Yamin, P.; Yasuda, T.; Yatsunenko, Y.; Yip, K.; Youssef, S.; Yu, J.; Yu, Z.; Zanabria, M.; Zhang, X.; Zheng, H.; Zhou, B.; Zhou, Z.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.
2002-03-01
The DØ Collaboration has studied for the first time the properties of hadron-collider jets reconstructed with a successive-combination algorithm based on relative transverse momenta (k⊥) of energy clusters. Using the standard value D=1.0 of the jet-separation parameter in the k⊥ algorithm, we find that the pT of such jets is higher than the ET of matched jets reconstructed with cones of radius R=0.7, by about 5 (8) GeV at pT~90 (240) GeV. To examine internal jet structure, the k⊥ algorithm is applied within D=0.5 jets to resolve any subjets. The multiplicity of subjets in jet samples at (s)=1800 GeV and 630 GeV is extracted separately for gluons (Mg) and quarks (Mq), and the ratio of average subjet multiplicities in gluon and quark jets is measured as (
Kaluza-Klein gluon + jets associated production at the Large Hadron Collider
NASA Astrophysics Data System (ADS)
Iyer, A. M.; Mahmoudi, F.; Manglani, N.; Sridhar, K.
2016-08-01
The Kaluza-Klein excitations of gluons offer the exciting possibility of probing bulk Randall-Sundrum (RS) models. In these bulk models either a custodial symmetry or a deformation of the metric away from AdS is invoked in order to deal with electroweak precision tests. Addressing both these models, we suggest a new channel in which to study the production of KK-gluons (gKK): one where it is produced in association with one or more hard jets. The cross-section for the gKK + jets channel is significant because of several contributing sub-processes. In particular, the 1-jet and the 2-jet associated processes are important because at these orders in QCD the qg and the gg initial states respectively come into play. We have performed a hadron-level simulation of the signal and present strategies to effectively extract the signal from what could potentially be a huge background. We present results for the kinematic reach of the LHC Run-II for different gKK masses in bulk-RS models.
Deep-Elastic pp Scattering at Lhc from LOW-x Gluons
NASA Astrophysics Data System (ADS)
Islam, M. M.; Kašpar, J.; Luddy, R. J.
Deep-elastic pp scattering at c.m. energy 14 TeV at LHC in the momentum transfer range 4 GeV2 ≲ |t| ≲ 10 GeV2 is planned to be measured by the TOTEM group. We study this process in a model where the deep-elastic scattering is due to a single hard collision of a valence quark from one proton with a valence quark from the other proton. The hard collision originates from the low-x gluon cloud around one valence quark interacting with that of the other. The low-x gluon cloud can be identified as color glass condensate and has size ≃0.3 F. Our prediction is that pp dσ/dt in the large |t| region decreases smoothly as momentum transfer increases. This is in contrast to the prediction of pp dσ/dt with visible oscillations and smaller cross sections by a large number of other models.
Medium-induced gluon radiation and colour decoherence beyond the soft approximation
NASA Astrophysics Data System (ADS)
Apolinário, Liliana; Armesto, Néstor; Milhano, José Guilherme; Salgado, Carlos A.
2015-02-01
We derive the in-medium gluon radiation spectrum off a quark within the path integral formalism at finite energies, including all next-to-eikonal corrections in the propagators of quarks and gluons. Results are computed for finite formation times, including interference with vacuum amplitudes. By rewriting the medium averages in a convenient manner we present the spectrum in terms of dipole cross sections and a colour decoherence parameter with the same physical origin as that found in previous studies of the antenna radiation. This factorisation allows us to present a simple physical picture of the medium-induced radiation for any value of the formation time, that is of interest for a probabilistic implementation of the modified parton shower. Known results are recovered for the particular cases of soft radiation and eikonal quark and for the case of a very long medium, with length much larger than the average formation times for medium-induced radiation. Technical details of the computation of the relevant n-point functions in colour space and of the required path integrals in transverse space are provided. The final result completes the calculation of all finite energy corrections for the radiation off a quark in a QCD medium that exist in the small angle approximation and for a recoilless medium.
Equation of State for a Quark Gluon Plasma in the Fuzzy Bag Model
NASA Astrophysics Data System (ADS)
Jacobsen, R. B.; Vasconcellos, C. A. Z.; Bodmann, Bardo E. J.; Dillig, Manfred
2004-12-01
We study two distinct phases of nuclear matter, a baryon-meson phase and a quark-gluon phase (QGP). For the baryon-meson phase we develop an equation of state (EoS) using a quark-meson formulation based on a new version of the fuzzy bag model with scalar-isoscalar, vector-isoscalar and vector-isovector meson-quark couplings and leptonic degrees of freedom as well as the constraints of chemical equilibrium, baryon number and electric charge conservation. For the QGP phase we model an EoS for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas. Our main results indicate the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature are slightly modified in comparison to the predictions based on the MIT bag model with a constant B.
Heavy-quark transport coefficients in a hot viscous quark-gluon plasma medium
NASA Astrophysics Data System (ADS)
Das, Santosh K.; Chandra, Vinod; Alam, Jan-e.
2014-01-01
Heavy-quark (HQ) transport coefficients have been estimated for a viscous quark-gluon plasma (QGP) medium, utilizing a recently proposed quasi-particle description based on a realistic QGP equation of state (EoS). Interactions entering through the EoS significantly suppress the temperature dependence of the drag coefficient of QGP, compared to those of an ideal relativistic system of quarks and gluons. The inclusion of shear and bulk viscosities through the corrections to the thermal phase space factors of the bath particles alters the magnitude of the drag coefficient; the enhancement is significant at lower temperatures. In the competition between the effects of the EoS and dissipative corrections through phase space factors, the former eventually dictate how the drag coefficient would behave as a function of temperature and how much it quantitatively digresses from the ideal case. The observations suggest a significant impact of both the realistic EoS and the viscosities on the HQs transport at Relativistic Heavy Ion Collider and Large Hadron Collider collision energies.
Equation of state for hot quark-gluon plasma transitions to hadrons with full QCD potential
NASA Astrophysics Data System (ADS)
Sheikholeslami-Sabzevari, Bijan
2002-05-01
A practical method based on Mayer's cluster expansion to calculate critical values for a quark-gluon plasma (QGP) phase transition to hadrons is represented. It can be applied to a high-temperature QGP for clustering of quarks to mesons and baryons. The potential used is the Cornell potential, i.e., a potential containing both confining and gluon exchange terms. Debye screening effects are included. An equation of state (EOS) for hadron production is found by analytical methods, which is valid near the critical point. The example of the formation of J/ψ and Υ is recalculated. It is shown that in the range of temperatures available by today's accelerators, the latter particles are suppressed. This is further confirmation for heavy quarkonia suppression and, hence, for a signature of a QGP. The EOS presented here also shows that in future colliders there will be no heavy quarkonia production by the mechanism of phase transition. Hence, if there will be heavy quarkonia production, it must be based on some other mechanisms, perhaps on the basis of some recently suggested possibilities.
Quark-Gluon Plasma in a Bag Model with a Soft Surface
NASA Astrophysics Data System (ADS)
Jacobsen, Rafael B.; Marranghello, Guilherme F.; Vasconcellos, César A. Z.; Mesquita, Alexandre
We analyze the implications of quantum hadrodynamics (QHD) and quantum chromodynamics (QCD) to model, respectively, two distinct phases of nuclear matter, a baryon-meson phase and a quark-gluon phase. We develop an equation of state (EoS) in the framework of a quark-meson coupling model for the hadron-meson phase using a new version of the fuzzy bag model with scalar-isoscalar, vector-isoscalar and vector-isovector meson-quark couplings and leptonic degrees of freedom as well as the constrains from chemical equilibrium, baryon number and electric charge conservation. We model the EoS for the QGP phase for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas as determined by thermodynamics. Our predictions yield the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature. Our results are slightly modified in comparison to predictions based on the standard MIT bag model with a constant bag pressure B.
Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas
Xu, J.; Liao, J.; Gyulassy, M.
2015-12-01
Here, we build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near “perfect fluid” like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. Moreover, a quantitative connection between the shear viscosity and jet transport parameter is rigorously established within this framework. Finally, we deduce the T = 160-600 MeV dependence of the QGP’s η/s: its near vanishing value in the near T_{c} regime is determined by the composition of E and M charges, it increases as T rises, and its high T limit is fixed by color screening scales.
Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas
Xu, J.; Liao, J.; Gyulassy, M.
2015-12-01
Here, we build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near “perfect fluid” like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. Moreover, a quantitative connection between the shear viscosity and jet transportmore » parameter is rigorously established within this framework. Finally, we deduce the T = 160-600 MeV dependence of the QGP’s η/s: its near vanishing value in the near Tc regime is determined by the composition of E and M charges, it increases as T rises, and its high T limit is fixed by color screening scales.« less
Jet Tomography of Quark Gluon Plasmas in High Energy Nuclear Collisions
NASA Astrophysics Data System (ADS)
Gyulassy, Miklos
2015-04-01
The attenuation pattern of high energy jet fragments in ultra-relativistic nuclear collisions provides information on the space-time evolution and dynamical properties of the Quark Gluon Plasma (QGP) phase of matter discovered at the Relativistic Heavy Ion Collider (RHIC) and observed at higher densities at the Large Hadron Collider (LHC). First I review our jet tomography theory of quark and gluon energy loss in a weakly coupled picture of the QGP. While the average attenuation pattern of light and heavy quark jets were well accounted for in that picture, the predicted azimuthal elliptic asymmetry of jets was underestimated when realistic bulk collective flow effects were taken into account. I then show that the elliptic asymmetry of jet fragments can also be quantitatively understood when nonperturbative lattice QCD constraints on the suppression of color electric fluctuations and the enhancement of color magnetic fluctuations near the critical QCD confinement temperature, Tc ~ 160 MeV, are incorporated into the theory. Our analysis provides a novel quantitative connection between the jet transport properties controlling the hard jet quenching observables and the bulk viscous transport properties controlling the remarkable ``perfect fluidity'' of QGP observed at RHIC and LHC.
Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas
NASA Astrophysics Data System (ADS)
Xu, Jiechen; Liao, Jinfeng; Gyulassy, Miklos
2016-12-01
We build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near "perfect fluid" like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. A quantitative connection between the shear viscosity and jet transport parameter is rigorously established within this framework. We deduce the T = 160 - 600 MeV dependence of the QGP's η / s: its near vanishing value in the near Tc regime is determined by the composition of E and M charges, it increases as T rises, and its high T limit is fixed by color screening scales.
Malheiro, M.; Dey, M.; Delfino, A.; Dey, J. |||
1997-01-01
It is known now that chiral symmetry restoration requires the meson-nucleon couplings to be density-dependent in nuclear-matter mean-field models. We further show that, quite generally, the quark and gluon condensates in medium are related to the trace of the energy-momentum tensor of nuclear matter and in these models the incompressibility K must be less than 3 times the chemical potential {mu}. In the critical density {rho}{sub c}, the gluon condensate is only reduced by 20{percent}, indicating a larger effective nucleon mass. {copyright} {ital 1997} {ital The American Physical Society}
Valence-quark distribution functions in the kaon and pion
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-18
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson’s momentum at a characteristic hadronic scale and vanish as ( 1 - x ) ^{2} when Bjorken- x → 1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U ( 3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion’s light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
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.
What (if anything) can few-body strange systems teach us about quark-gluon hadronic substructure
Maltman, K. . Dept. of Physics Los Alamos National Lab., NM )
1990-01-01
We discuss expectation, relevant to the proposed ({pi},K) program at PILAC, for the effects of hadronic quark-gluon substructure on the physics of few-body strangeness {minus}1 systems, in the context of QCD-inspired models used previously to describe the hadron spectrum and short distance nucleon-nucleon scattering. 50 refs., 2 tabs.
Quark-gluon plasma in the early Universe and in ultra-relativistic heavy-ion collisions
Greco, V.
2014-05-09
We briefly give an elementary introduction to the expansion of the Early Universe till when the phase transition of the quark-gluon plasma to a hadronic matter takes place. Then we describe some main element of the study of QGP by mean of ultra-relativistic heavy-ion collisions (uRHIC's)
Equilibration Rates in a Strongly Coupled Nonconformal Quark-Gluon Plasma.
Buchel, Alex; Heller, Michal P; Myers, Robert C
2015-06-26
We initiate the study of equilibration rates of strongly coupled quark-gluon plasmas in the absence of conformal symmetry. We primarily consider a supersymmetric mass deformation within N=2^{*} gauge theory and use holography to compute quasinormal modes of a variety of scalar operators, as well as the energy-momentum tensor. In each case, the lowest quasinormal frequency, which provides an approximate upper bound on the thermalization time, is proportional to temperature, up to a prefactor with only a mild temperature dependence. We find similar behavior in other holographic plasmas, where the model contains an additional scale beyond the temperature. Hence, our study suggests that the thermalization time is generically set by the temperature, irrespective of any other scales, in strongly coupled gauge theories.
Solving the ghost-gluon system of Yang-Mills theory on GPUs
NASA Astrophysics Data System (ADS)
Hopfer, Markus; Alkofer, Reinhard; Haase, Gundolf
2013-04-01
We solve the ghost-gluon system of Yang-Mills theory using graphics processing units (GPUs). Working in the Landau gauge, we use the Dyson-Schwinger formalism for the mathematical description, as this approach is well suited to directly benefit from the computing power of the GPUs. With the help of a Chebyshev expansion for the dressing functions and a subsequent appliance of a Newton-Raphson method, the non-linear system of coupled integral equations is linearized. The resulting Newton matrix is generated in parallel using OpenMPI and CUDA™. Our results show that it is possible to cut down the run time by two orders of magnitude as compared to a sequential version of the code. This makes the proposed techniques well suited for Dyson-Schwinger calculations on more complicated systems where the Yang-Mills sector of QCD serves as a starting point. In addition, the computation of Schwinger functions using GPU devices is studied.
NASA Astrophysics Data System (ADS)
Cao, Shanshan; Luo, Tan; Qin, Guang-You; Wang, Xin-Nian
2016-07-01
A linearized Boltzmann transport (LBT) model coupled with hydrodynamical background is established to describe the evolution of jet shower partons and medium excitations in high energy heavy-ion collisions. We extend the LBT model to include both elastic and inelastic processes for light and heavy partons in the quark-gluon plasma. A hybrid model of fragmentation and coalescence is developed for the hadronization of heavy quarks. Within this framework, we investigate how heavy flavor observables depend on various ingredients, such as different energy loss and hadronization mechanisms, the momentum and temperature dependences of the transport coefficients, and the radial flow of the expanding fireball. Our model calculations show good descriptions of the D meson suppression and elliptic flow observed at the Larege Hadron Collider and the Relativistic Heavy-Ion Collider. The prediction for the Pb-Pb collisions at √{sN N}=5.02 TeV is provided.
Insights from the ALICE quark-gluon coloured world at the LHC
NASA Astrophysics Data System (ADS)
Cifarelli, L.; Nania, R.; Noferini, F.; Scapparone, , E.; Zichichi, A.
2016-10-01
Interactions among heavy ions at the CERN LHC collider recreate the state of matter as it was a few micro-seconds after the Big Bang: the Quark Gluon Coloured World (QGCW). At a centre-of-mass energy of 2.76TeV the produced QGCW reaches unprecedented temperatures, volumes and durations allowing more refined studies of its properties. Data collected during LHC Run1 (from 2010 to 2013) already provided new and sometimes unexpected results, and pointed to intriguing similarities among high multiplicity events produced in different colliding systems, namely pp, p-Pb and Pb-Pb. A comprehensive review of these results is presented, showing how heavy-ion physics is a powerful tool to shed light on QCD in such extreme conditions when multiple phase transitions should occur to go from the QGCW to our present non-coloured world.
Probing the Quark Sea and Gluons: the Electron-Ion Collider Projects
Rolf Ent
2012-04-01
EIC is the generic name for the nuclear science-driven Electron-Ion Collider presently considered in the US. Such an EIC would be the world’s first polarized electron-proton collider, and the world’s first e-A collider. Very little remains known about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons of Quantum Chromodynamics (QCD). A large community effort to sharpen a compelling nuclear science case for an EIC occurred during a ten-week program taking place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The critical capabilities of a stage-I EIC are a range in center-of-mass energies from 20 to 70 GeV and variable, full polarization of electrons and light ions (the latter both longitudinal and transverse), ion species up to A=200 or so, multiple interaction regions, and a high luminosity of about 10{sup 34} electron-nucleons per cm{sup 2} and per second. The physics program of such a stage-I EIC encompass inclusive measurements (ep/A{yields}e'+X), which require detection of the scattered lepon and/or the full scattered hadronic debris with high precision, semi-inclusive processes (ep/A{yields}e'+h+X), which require detection in coincidence with the scattered lepton of at least one (current or target region) hadron; and exclusive processes (ep/A{yields}e'+N'/A'+{gamma}/m), which require detection of all particles in the reaction. The main science themes of an EIC are to i) map the spin and spatial structure of quarks and gluons in nucleons, ii) discover the collective effects of gluons in atomic nuclei, and (iii) understand the emergence of hadronic matter from color charge. In addition, there are opportunities at an EIC for fundamental symmetry and nucleon structure measurements using the electroweak probe. To truly make headway to image the sea quarks and gluons in nucleons and nuclei, the EIC needs high luminosity over a range of energies as more exclusive
Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions
Chien, Y. T.; Cirigliano, V.; Dekens, W.; de Vries, J.; Mereghetti, E.
2016-02-01
Here we investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We also show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue that Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. But, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.
Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions
Chien, Y. T.; Cirigliano, V.; Dekens, W.; ...
2016-02-01
Here we investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We also show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue thatmore » Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. But, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.« less
Quarkonium Suppression in a Strongly-Coupled Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Vairo, Antonio
2017-03-01
We compute the quarkonium nuclear modification factor in a strongly coupled quark-gluon plasma for quarkonia that are S-wave Coulombic bound states. We perform the analysis in a non-relativistic effective field theory framework that is accurate at leading-order in the heavy-quark density expansion and at next-to-leading order in the multipole expansion. We write and solve the Lindblad equation for the heavy quark-antiquark density. Thermal mass shift, width and the Lindblad equation depend on only two non-perturbative parameters: the heavy-quark momentum diffusion coefficient and its dispersive counterpart. Finally, we provide preliminary numerical results for the nuclear modification factors of the 1 S and 2 S bottomonium states.
Classical strongly coupled quark-gluon plasma. II. Screening and equation of state
NASA Astrophysics Data System (ADS)
Gelman, Boris A.; Shuryak, Edward V.; Zahed, Ismail
2006-10-01
We analyze the screening and bulk energy of a classical and strongly interacting plasma of color charges, a model we recently introduced for the description of a quark-gluon plasma at T=(1-3)Tc. The partition function is organized around the Debye-Hückel limit. The linear Debye-Hückel limit is corrected by a virial expansion. For the pressure, the expansion is badly convergent even in the dilute limit. The nonlinear Debye-Hückel theory is studied numerically as an alternative for moderately strong plasmas. We use the Debye theory of solid to extend the analysis to the crystal phase at very strong coupling. The analytical results for the bulk energy per particle compare well with the numerical results from molecular dynamics simulations for all couplings.
Nonperturbative heavy-quark diffusion in the quark-gluon plasma.
van Hees, H; Mannarelli, M; Greco, V; Rapp, R
2008-05-16
We evaluate heavy-quark (HQ) transport properties in a quark-gluon plasma (QGP) within a Brueckner many-body scheme employing interaction potentials extracted from thermal lattice QCD. The in-medium T matrices for elastic charm- and bottom-quark scattering off light quarks in the QGP are dominated by attractive meson and diquark channels which support resonance states up to temperatures of ~1.5T(c). The resulting drag coefficient increases with decreasing temperature, contrary to expectations based on perturbative QCD scattering. Employing relativistic Langevin simulations we compute HQ spectra and elliptic flow in sqrt[s(NN)]=200 GeV Au-Au collisions. A good agreement with electron decay data supports our nonperturbative computation of HQ diffusion, indicative for a strongly coupled QGP.
Flow at the SPS and RHIC as a quark-gluon plasma signature.
Teaney, D; Lauret, J; Shuryak, E V
2001-05-21
Radial and elliptic flow in noncentral heavy-ion collisions can constrain the effective equation of state (EOS) of the excited nuclear matter. To this end, a model combining relativistic hydrodynamics and a hadronic transport code [Sorge, Phys. Rev. C 52, 3291 (1995)] is developed. For an EOS with a first-order phase transition, the model reproduces both the radial and elliptic flow data at the SPS. With the EOS fixed from SPS data, we quantify predictions at RHIC where the quark-gluon plasma (QGP) pressure is expected to drive additional radial and elliptic flows. Currently, the strong elliptic flow observed in the first RHIC measurements does not conclusively signal this nascent QGP pressure.
Pion interferometry at RHIC: porobing a thermalized quark-gluon plasma?
Soff, S; Bass, S A; Dumitru, A
2001-04-30
We calculate the Gaussian radius parameters of the pion-emitting source in high-energy heavy-ion collisions, assuming a first-order phase transition from a thermalized quark-gluon plasma (QGP) to a gas of hadrons. Such a model leads to a very long-lived dissipative hadronic rescattering phase which dominates the properties of the two-pion correlation functions. The radii are found to depend only weakly on the thermalization time tau(i), the critical temperature Tc (and thus the latent heat), and the specific entropy of the QGP. The model calculations suggest a rapid increase of R(out)/R(side) as a function of KT if a thermalized QGP were formed.
200 A GeV Au + Au collisions serve a nearly perfect quark-gluon liquid.
Song, Huichao; Bass, Steffen A; Heinz, Ulrich; Hirano, Tetsufumi; Shen, Chun
2011-05-13
A new robust method to extract the specific shear viscosity (η/s)(QGP) of a quark-gluon plasma (QGP) at temperatures T(c) < T ≲ 2T(c) from the centrality dependence of the eccentricity-scaled elliptic flow v2/ε measured in ultrarelativistic heavy-ion collisions is presented. Coupling viscous fluid dynamics for the QGP with a microscopic transport model for hadronic freeze-out we find for 200 A GeV Au + Au collisions that v2/ε is a universal function of multiplicity density (1/S)(dN(ch)/dy) that depends only on the viscosity but not on the model used for computing the initial fireball eccentricity ε. Comparing with measurements we find 1<4π(η/s)(QGP) < 2.5 where the uncertainty range is dominated by model uncertainties for the values of ε used to normalize the measured v2.
Apparent thermalization due to plasma instabilities in the quark-gluon plasma.
Arnold, Peter; Lenaghan, Jonathan; Moore, Guy D; Yaffe, Laurence G
2005-02-25
Hydrodynamical modeling of heavy-ion collisions at RHIC suggests that the quark-gluon plasma (QGP) "thermalizes" in a remarkably short time scale, about 0.6 fm/c. We argue that this should be viewed as indicating fast isotropization, but not necessarily complete thermalization, of the nonequilibrium QGP. Non-Abelian plasma instabilities can drive local isotropization of an anisotropic QGP on a time scale which is faster than ordinary perturbative scattering processes. As a result, we argue that theoretical expectations based on weak-coupling analysis are not necessarily in conflict with hydrodynamic modeling of the early part of RHIC collisions, provided one recognizes the key role of non-Abelian plasma instabilities.
Flow at the SPS and RHIC as a Quark-Gluon Plasma Signature
NASA Astrophysics Data System (ADS)
Teaney, D.; Lauret, J.; Shuryak, E. V.
2001-05-01
Radial and elliptic flow in noncentral heavy-ion collisions can constrain the effective equation of state (EOS) of the excited nuclear matter. To this end, a model combining relativistic hydrodynamics and a hadronic transport code [Sorge, Phys. Rev. C 52, 3291 (1995)] is developed. For an EOS with a first-order phase transition, the model reproduces both the radial and elliptic flow data at the SPS. With the EOS fixed from SPS data, we quantify predictions at RHIC where the quark-gluon plasma (QGP) pressure is expected to drive additional radial and elliptic flows. Currently, the strong elliptic flow observed in the first RHIC measurements does not conclusively signal this nascent QGP pressure.
Higgs-gluon coupling in warped extra dimensional models with brane kinetic terms
NASA Astrophysics Data System (ADS)
Dey, Ujjal Kumar; Ray, Tirtha Sankar
2016-01-01
Warped models with the Higgs confined to the weak brane and the gauge and matter fields accessing the AdS5 bulk provide a viable setting to address the gauge hierarchy problem. Brane kinetic terms for the bulk fields are known to ease some of the tensions of these models with precision electroweak observables and flavor constraints. We study the loop-driven Higgs coupling to the gluons that are relevant to the Higgs program at the LHC, in this scenario. We demonstrate a partial cancellation in the contribution of the fermionic Kaluza-Klein (KK) towers within such framework relatively independent of the 5D parameters. The entire dependence of this coupling on the new physics arises from the mixing between the Standard Model states and the KK excitations. We find that the present precision in measurement of these couplings can lead to a constraint on the KK scale up to 1.2 TeV at 95% confidence level.
Higgs production via gluon fusion in k{sub T} factorisation
Hautmann, F.; Jung, H.; Pandis, V.
2011-07-15
Theoretical studies of Higgs production via gluon fusion are frequently carried out in the limit where the top quark mass is much larger than the Higgs mass, an approximation which reduces the top quark loop to an effective vertex. We present a numerical analysis of the error thus introduced by performing a Monte Carlo calculation for gg{yields}h in k{sub T}-factorisation, using the parton shower generator CASCADE. By examining both inclusive and exclusive quantities, we find that retaining the top-mass dependence results in only a small enhancement of the cross-section. We then proceed to compare CASCADE to the collinear Monte Carlos PYTHIA, MC-NLO and POWHEG.
Are v2 measurements consistent with the formation of the Quark Gluon Plasma at RHIC?
NASA Astrophysics Data System (ADS)
Lacey, Roy A.
2002-04-01
Two-particle and multi-particle correlation measurements have been predicted to serve as an important probe for the high energy density nuclear matter expected in Au + Au collisions at RHIC [1,2,3]. In recent experiments, the PHENIX collaboration has made such measurements for a wide range of transverse momentum and impact parameter selections. Selected results from these measurements will be presented, and I will discuss whether or not they are compatible with possible quark gluon plasma formation in RHIC collisions. [1] Teaney & Shuryak PRL 83, 4951, (1999). [2] M. Gyulassy and X.N. Wang, Nucl. Phys. B420 583 (1994). [3] X.N. Wang, Phys. Rev. C58 2321 (1998).
Time-Dependence of the Survival Probability of Quarkonia in Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Mah Hussin, Noor Sabrina; Shalaby, Asmaa; Petridis, Athanasios
2015-10-01
The time-dependent Schrödinger equation is used to study the formation of quarkonia and their propagation in Quark-Gluon Plasma (QGP). The initial bound (ground) state is computed using imaginary-time propagation in a confining potential. The QGP is simulated with a confining potential of an extended asymptotic freedom region. The interior of the QGP potential may correspond to a vacuum that differs from that of the exterior region. The initial state propagates through this potential in real time. The survival probability is calculated versus time for various potential parameters and relative momenta of the quarkonium by projecting the interacting wavefunction onto its freely-propagating counterpart. In these calculations the staggered-leap frog method is used with special attention paid to the issue of stability. It is found that quarkonium decay is typically non-exponential. Fast moving states decay faster. Connection with experimental results is done by means of cross-section ratios.
NASA Astrophysics Data System (ADS)
Buchel, Alex; Heller, Michal P.; Noronha, Jorge
2016-11-01
Microseconds after the Big Bang quarks and gluons formed a strongly coupled nonconformal liquid driven out of equilibrium by the expansion of the Universe. We use holography to determine the nonequilibrium behavior of this liquid in a Friedmann-Lemaître-Robertson-Walker universe and develop an expansion for the corresponding entropy production in terms of the derivatives of the cosmological scale factor. We show that the resulting series has zero radius of convergence and we discuss its resurgent properties. Finally, we compute the resummed entropy production rate in a de Sitter universe at late times and show that the leading order approximation given by bulk viscosity effects can strongly overestimate/underestimate the rate depending on the microscopic parameters.
Fragmentation of quarks and gluons, tests of QCD in e/sup +/e/sup -/ annihilation
Dorfan, J.
1983-10-01
This report covers the topics of fragmentation of quarks and gluons and tests of QCD in e/sup +/e/sup -/ annihilation and is a summary of a rapporteur talk given at the 1983 International Symposium on Lepton and Photon Interactions at High Energies. New data on the general characteristics of the e/sup +/e/sup -/ environment at the UPSILON and at PETRA and PEP are discussed. For the first time there is a lot of data on resonance production - eta, K*, rho, phi, ..xi... There is more data on c quark fragmentation from tagged D/sup *+-/ and direct observation of D/sup +/ and D/sup 0/. There are four experiments using high P/sub t/ leptons to measure the b quark fragmentation function - agreement amongst the experiments is very good. All these measurements can usefully be incorporated in the Monte Carlo simulation models. QCD tests are discussed. ..cap alpha../sub 3/ has been measured using the energy dependence of the total hadronic cross section. Unfortunately this method is not very precise. Other measurements of ..cap alpha../sub 3/ from shape analyses and energy-energy correlations have been done including the effects of all second order QCD diagrams. The results seem to depend both on the procedure and the models used to extract ..cap alpha../sub 3/. The evidence for differences in gluon and quark fragmentation are reviewed. There is now evidence that baryon conservation occurs locally in a jet rather than globally in an event. Multiplicity and jet mass correlations are presented as well as data on KNO scaling. 46 references.
Heavy-light decay topologies as a new strategy to discover a heavy gluon
NASA Astrophysics Data System (ADS)
Bini, Cesare; Contino, Roberto; Vignaroli, Natascia
2012-01-01
We study the collider phenomenology of the lightest Kaluza-Klein excitation of the gluon, G*, in theories with a warped extra dimension. We do so by means of a two-site effective lagrangian which includes only the lowest-lying spin-1 and spin-1/2 resonances. We point out the importance of the decays of G* to one SM plus one heavy fermion, that were overlooked in the previous literature. It turns out that, when kinematically allowed, such heavy-light decays are powerful channels for discovering the G*. In particular, we present a parton-level Montecarlo analysis of the final state W tb that follows from the decay of G* to one SM top or bottom quark plus its heavy partner. We find that at sqrt {s} = 7{text{TeV}} and with 10fb-1 of integrated luminosity, the LHC can discover a KK gluon with mass in the range M G* = (1 .8 - 2 .2) TeV if its coupling to a pair of light quarks is {g_{{G*qoverline q }}} = left( {0.2 - 0.5} right){g_3} . The same process is also competitive for the discovery of the top and bottom partners as well. We find, for example, that the LHC at sqrt {s} = {7}{text{TeV}} can discover a 1 TeV KK bottom quark with an integrated luminosity of (5 .3 - 0 .61) fb-1 for {g_{{G*qoverline q }}} = left( {0.2 - 0.5} right){g_3}.
5th International conference on Physics and Astrophysics of Quark Gluon Plasma
NASA Astrophysics Data System (ADS)
Sinha, Bikash; Alam, Jan-E.; Nayak, Tapan K.
2006-11-01
The 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2005) was held on 8 - 12 February 2005 at the Variable Energy Cyclotron Centre and Saha Institute of Nuclear Physics campus, Kolkata, India. The conference was enriched by the august presence of about 300 participants representing 18 countries across the globe. It had plenary talks and oral presentations, which form a part of these proceedings. Besides invited and contributed talks there were also a large number of poster presentations. The conference was energized by discussions of fresh experimental data from RHIC on strong elliptic flow, jet quenching, single photon spectra etc. Moreover, new theoretical results were brought to the discussion forum during this conference. Colour glass condensates, hydrodynamical flow, jet quenching and sQGP were intensely debated by the participants. The highlight of ICPAQGP 2005 was the presentation of fresh experimental results from the RHIC-IV run. The ICPAQGP series, since its inception in 1988, has placed emphasis on the role of quark matter in the fields of astrophysics and cosmology. The subsequent conferences held in 1993, 1997, 2001 and 2005 had also retained this focus. The conference was preceded by a Fest Colloquium in honour of Professor Bikash Sinha. Professor Sinha, regarded as the pioneer in establishing quark gluon plasma research in India, has successfully encouraged a group of young Indian researchers to devote themselves wholeheartedly to QGP research - both theoretical and experimental. Members of the International Advisory Committee played a pivotal role mainly in the selection of speakers. The contributions of the Organizing Committee in all aspects, from selecting the contributory talks posters down to arranging local hospitality, were much appreciated. We thank the members of both committees for making ICPAQGP 2005 an interesting platform for scientific deliberation. The ICPAQGP 2005 was supported financially by
Constantinou, Martha; Panagopoulos, Haralambos; Skouroupathis, Apostolos; Stylianou, Fotos; Dimopoulos, Petros; Frezzotti, Roberto
2011-04-01
In this work we calculate the corrections to the amputated Green's functions of four-fermion operators, in 1-loop lattice perturbation theory. One of the novel aspects of our calculations is that they are carried out to second order in the lattice spacing, O(a{sup 2}). We employ the Wilson/clover action for massless fermions (also applicable for the twisted mass action in the chiral limit) and a family of Symanzik improved actions for gluons. Our calculations have been carried out in a general covariant gauge. Results have been obtained for several popular choices of values for the Symanzik coefficients (Plaquette, Tree-level Symanzik, Iwasaki, TILW and DBW2 action). While our Green's function calculations regard any pointlike four-fermion operators which do not mix with lower dimension ones, we pay particular attention to {Delta}F=2 operators, both parity conserving and parity violating (F stands for flavor: S, C, B). By appropriately projecting those bare Green's functions we compute the perturbative renormalization constants for a complete basis of four-fermion operators and we study their mixing pattern. For some of the actions considered here, even O(a{sup 0}) results did not exist in the literature to date. The correction terms which we calculate (along with our previous O(a{sup 2}) calculation of Z{sub {Psi}}[M. Constantinou, V. Lubicz, H. Panagopoulos, and F. Stylianou, J. High Energy Phys. 10 (2009) 064.][M. Constantinou, P. Dimopoulos, R. Frezzotti, G. Herdoiza, K. Jansen, V. Lubicz, H. Panagopoulos, G. C. Rossi, S. Simula, F. Stylianou, and A. Vladikas, J. High Energy Phys. 08 (2010) 068.][C. Alexandrou, M. Constantinou, T. Korzec, H. Panagopoulos, and F. Stylianou (unpublished).]) are essential ingredients for minimizing the lattice artifacts which are present in nonperturbative evaluations of renormalization constants with the RI{sup '}-MOM method. Our perturbative results, for the matrix elements of {Delta}F=2 operators and for the corresponding
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.
Bhattacharya, Lusaka; Roy, Pradip
2009-05-15
We calculate transverse momentum distribution of direct photons from various sources by taking into account the initial state momentum anisotropy of quark-gluon plasma (QGP) and late stage transverse flow effects. To evaluate the photon yield from hadronic matter we include the contributions from baryon-meson reactions. The total photon yield, calculated for various combinations of initial conditions and transition temperatures, is then compared with the recent measurement of photon transverse momentum distribution by the PHENIX Collaboration. It is shown that because of the initial state anisotropy the photon yield from the QGP is larger by a factor of 8-10 than that of the isotropic case in the intermediate p{sub T} regime. It is also demonstrated that the presence of such an anisotropy can describe the PHENIX photon data better than the isotropic case in the present model. We show that the isotropization time thus extracted lies within the range 1.5{>=}{tau}{sub iso}{>=}0.5 fm/c for the initial conditions used here.
Bridging soft-hard transport properties of quark-gluon plasmas with CUJET3.0
Xu, Jiechen; Liao, Jinfeng; Gyulassy, Miklos
2016-02-01
A new model (CUJET3.0) of jet quenching in nuclear collisions coupled to bulk data constrained (VISH2+1D) viscous hydrodynamic backgrounds is constructed by generalizing the perturbative QCD based (CUJET2.0) model to include two complementary non-perturbative chromodynamical features of the QCD con_nement cross-over phase transition near Tc ≈ 160 MeV: (1) the suppression of quark and gluon chromo-electric-charged (cec) degrees of freedom and (2) the emergence of chromo-magnetic-monopole (cmm) degrees of freedom. Such a semi Quark Gluon Monopole Plasma (sQGMP) microscopic scenario is tested by comparing predictions of the leading hadron nuclear modification factors, RAAh (pT > 10GeV=c;√s), and their azimuthal ellipticmore » asymmetry v2h (pT > 10GeV=c;√s) with available data on h =π, D;B jet fragments from nuclear collisions at RHIC (√s = 0.2 ATeV) and LHC(√s = 2.76 ATeV). The cmm degrees of freedom in the sQGMP model near Tc are shown to solve robustly the long standing RAA vs v2 puzzle by predicting a maximum of the jet quenching parameter field g(E; T)/T3 near Tc. The robustness of CUJET3.0 model to a number of theoretical uncertainties is critically tested. Moreover the consistency of jet quenching with observed bulk perfect uidity is demonstrated by extrapolating the sQGMP qˆ down to thermal energy E ~ 3T scales and showing that the sQGMP shear viscosity to entropy density ratio η/s ≈ T3/qˆ falls close to the unitarity bound, 1/4π, in the range (1–2)Tc. Detailed comparisons of the CUJET2.0 and CUJET3.0 models reveal the fact that remarkably different qˆ(T) dependence could be consistent with the same RAA data and could only be distinguished by anisotropy observables. Furthermore, these findings demonstrate clearly the inadequacy of focusing on the jet path averaged quantity as the only relevant medium property to characterize jet quenching, and point to the crucial roles of other essential factors beyond just the , such as the chromo
Evidences of quark-gluon plasma formation in central nuclear collisions
NASA Astrophysics Data System (ADS)
Sagun, V. V.; Bugaev, K. A.; Ivanytskyi, A. I.; Oliinychenko, D. R.
2017-01-01
Due to the absence of clear and unambiguous theoretical signals of the deconfinement transition from hadron matter to quark-gluon plasma (QGP) the experimental searches of QGP formation are based the analysis of various irregularities in the collision energy dependence of thermodynamic and hydrodynamic quantities. Here we present several remarkable irregularities at chemical freeze-out (CFO) of hadrons which are found using an advanced version of the hadron resonance gas model (HRGM). Among them are the sharp peaks of the trace anomaly and baryonic density which are seen at the center of mass energies √sNN = 4.9 GeV and √sNN = 9.2 GeV, and the two sets of highly correlated quasi-plateaus in the collision energy dependence of the entropy per baryon, total pion number per baryon, and thermal pion number per baryon which we found at the center of mass energies 3.8-4.9 GeV and 7.6-10 GeV. In addition we found a significant change of slope of the hadron yield ratios {Λ \\over p} and {{Λ - \\bar Λ } \\over {p - \\bar p}}, when the center of mass collision energy increases from 4.3 GeV to 4.9 GeV and from 7.6 GeV to 9.2 GeV [1]. The increase of slopes of these ratios at the collision energy interval 4.3-4.9 GeV is accompanied by a dramatic growth of resonance decays at CFO. We argue that such a strong correlation between the previously found irregularities and an enhancement of strangeness production can serve as the quark-gluon plasma formation signature. Hence, we conclude that a dramatic change of the system properties seen in the narrow collision energy range √sNN = 4.3-4.9 GeV may open entirely new possibilities for experimental studies of QGP properties at NICA JINR and FAIR GSI accelerators.
Bridging soft-hard transport properties of quark-gluon plasmas with CUJET3.0
NASA Astrophysics Data System (ADS)
Xu, Jiechen; Liao, Jinfeng; Gyulassy, Miklos
2016-02-01
A new model (CUJET3.0) of jet quenching in nuclear collisions coupled to bulk data constrained (VISH2+1D) viscous hydrodynamic backgrounds is constructed by generalizing the perturbative QCD based (CUJET2.0) model to include two complementary non-perturbative chromodynamical features of the QCD con_nement cross-over phase transition near Tc ≈ 160 MeV: (1) the suppression of quark and gluon chromo-electric-charged (cec) degrees of freedom and (2) the emergence of chromo-magnetic-monopole (cmm) degrees of freedom. Such a semi Quark Gluon Monopole Plasma (sQGMP) microscopic scenario is tested by comparing predictions of the leading hadron nuclear modification factors, R AA h ( pT > 10GeV =c ; √{s} ), and their azimuthal elliptic asymmetry v 2 h ( pT > 10GeV =c ; √{s} ) with available data on h =π, D;B jet fragments from nuclear collisions at RHIC ( √{s} = 0.2 ATeV) and LHC( √{s}=2.76 ATeV). The cmm degrees of freedom in the sQGMP model near T c are shown to solve robustly the long standing R AA vs v 2 puzzle by predicting a maximum of the jet quenching parameter field ĝ( E; T) /T 3 near T c . The robustness of CUJET3.0 model to a number of theoretical uncertainties is critically tested. Moreover the consistency of jet quenching with observed bulk perfect uidity is demonstrated by extrapolating the sQGMP widehat{q} down to thermal energy E 3 T scales and showing that the sQGMP shear viscosity to entropy density ratio η /s≈ {T}^3/widehat{q} falls close to the unitarity bound, 1 /4 π , in the range (1-2) Tc. Detailed comparisons of the CUJET2.0 and CUJET3.0 models reveal the fact that remarkably different widehat{q}(T) dependence could be consistent with the same R AA data and could only be distinguished by anisotropy observables. These _ndings demonstrate clearly the inadequacy of focusing on the jet path averaged quantity < widehat{q}rangle as the only relevant medium property to characterize jet quenching, and point to the crucial roles of other
QCD sum rule calculation of quark-gluon three-body components in the B-meson wave function
Nishikawa, Tetsuo; Tanaka, Kazuhiro
2011-10-21
We discuss the QCD sum rule calculation of the heavy-quark effective theory parameters {lambda}{sub E} and {lambda}{sub H}, which represent quark-gluon three-body components in the B-meson wave function. We update the sum rules for {lambda}{sub E,H} calculating the new higher-order contributions to the operator product expansion for the corresponding correlator, i.e., the order {alpha}{sub s} radiative corrections to the Wilson coefficients associated with the dimension-5 quark-gluon mixed condensate, and the power corrections due to the dimension-6 vacuum condensates. We find that the new radiative corrections significantly improve stability of the corresponding Borel sum rules, modifying the values of {lambda}{sub E,H}.
Impact factor for gluon production in multi-Regge kinematics in the next-to-leading order
Kozlov, M. G. Reznichenko, A. V. Fadin, V. S.
2012-07-15
The one-loop correction to the impact factor for gluon production upon the transition of a one-Reggeon state in the t channel to a two-Reggeon state is found. This impact factor is an element of multiparticle amplitudes in multi-Regge kinematics. The correction in question is necessary for developing the theory of Regge and multi-Regge processes. In particular, it is necessary for proving the multi-Regge form of the amplitude in the next-to-leading-logarithm approximation. This correction also makes it possible to complete the verification of the last of the unproven bootstrap conditions for gluon Reggeization and to prove, in this approximation, the validity of the multi-Regge form of the amplitude. All necessary calculations are presented, and an explicit expression for the impact factor in front of all possible color states in the t channel is given.
Adare, A.; Awes, Terry C; Cianciolo, Vince; Enokizono, Akitomo; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; PHENIX, Collaboration
2009-01-01
The double helicity asymmetry in neutral pion production for p{sub T} = 1 to 12 GeV/c was measured with the PHENIX experiment to access the gluon-spin contribution, {Delta}G, to the proton spin. Measured asymmetries are consistent with zero, and at a theory scale of {mu}{sup 2} = 4 GeV{sup 2} a next to leading order QCD analysis gives {Delta}G{sup [0.02,0.3]} = 0.2, with a constraint of -0.7 < {Delta}G{sup [0.02,0.3]} < 0.5 at {Delta}{chi}{sup 2} = 9 (-3{sigma}) for the sampled gluon momentum fraction (x) range, 0.02 to 0.3. The results are obtained using predictions for the measured asymmetries generated from four representative fits to polarized deep inelastic scattering data. We also consider the dependence of the {Delta}G constraint on the choice of the theoretical scale, a dominant uncertainty in these predictions.
Jet quenching and gluon to hadron fragmentation function in non-equilibrium QCD at RHIC and LHC
NASA Astrophysics Data System (ADS)
Nayak, Gouranga C.
2017-01-01
Theoretical understanding of the observed jet quenching measurements at RHIC and LHC is challenging in QCD because it requires understanding of parton to hadron fragmentation function in non-equilibrium QCD. In this paper, by using closed-time path integral formalism, we derive the gauge invariant definition of the gluon to hadron fragmentation function in non-equilibrium QCD which is consistent with factorization theorem in non-equilibrium QCD from first principles.
Time-Dependent Dynamics of Massive Quarkonium Resonances in Nuclear and Quark-Gluon-Plasma Media
NASA Astrophysics Data System (ADS)
Mah Hussin, Noor Sabrina; Shalaby, Asmaa; Petridis, Athanasios
2014-03-01
The time-dependent Schrödinger equation is used to study the formation of quarkonia and their propagation in Quark-Gluon Plasma (QGP) and nuclear media. The initial bound (ground) state is computed using imaginary-time propagation in a confining potential. The QGP is simulated with a confining potential of an extended asymptotic freedom region. The initial state propagates through this potential in real time. The nuclear medium is simulated with a periodic potential. In all cases the survival probability is calculated versus time for various potential parameters and relative momenta of the quarkonium with respect to the surrounding medium. In all calculations the staggered-leap frog method is used with special attention paid to the issue of stability. It is found that quarkonium decay is typically non-exponential. Fast moving states decay faster. There is a distinctive difference in the time-dependence of the survival probability between QGP and the nuclear medium. The effects of more realistic potentials are investigated.
NASA Astrophysics Data System (ADS)
Petersen, Hannah
2012-03-01
Recent measurements of higher order flow coefficients offer a more complete understanding of how hot and dense QCD matter is created in relativistic heavy ion collisions and what its properties are. In addition to providing new constraints on the viscosity of the quark gluon plasma, anisotropic flow is sensitive to the structure of the initial state. As elliptic flow (v2) is generated by the difference in pressure gradients that result from the initial almond shape of the reaction region in non-central collisions, higher order coefficients encode more detailed information about the event-by-event fluctuating initial state profile. In my talk, I will present an overview of theoretical work aimed at understanding the correlations between initial state structures and final state correlations and their origin and discuss the current status of initial state models. I will outline how the new experimental findings at RHIC and LHC can be used towards characterize the dynamical evolution of relativistic heavy ion collisions with special emphasis on the role of event-by-event approaches and sophisticated multi-parameter fits to achieve this goal.
Two-Loop QCD correction to massive spin-2 resonance → 3 gluons
NASA Astrophysics Data System (ADS)
Ahmed, Taushif; Mahakhud, Maguni; Mathews, Prakash; Rana, Narayan; Ravindran, V.
2014-05-01
We present the virtual QCD corrections to the process h → g + g + g due to interference of born and two-loop amplitudes, where h is a massive spin-2 particle and g is the gluon. We assume that the SM fields couple to h through the SM energy momentum tensor. Our result constitutes one of the ingredients to full NNLO QCD contribution to production of a massive spin-2 particle along with a jet in the scattering process at the LHC. In particular, this massive spin-2 could be a KK mode of a ADD graviton in large extra dimensional model or a RS KK mode in warped extra dimensional model or a generic massive spin-2. In addition, it provides an opportunity to study the ultraviolet and infrared structures of QCD amplitudes involving tensorial coupling resulting from energy momentum operator. Using dimensional regularization, we find that infrared poles of this amplitude are in agreement with the proposal by Catani confirming the factorization property of QCD amplitudes with tensorial insertion.
On the existence of a holographic description of the LHC quark-gluon plasmas
NASA Astrophysics Data System (ADS)
McInnes, Brett; Ong, Yen Chin
2017-04-01
Peripheral collisions of heavy ions can give rise to extremely intense magnetic fields. It has been suggested that these fields might invalidate the holographic description of the corresponding quark-gluon plasmas, assuming that these can be modelled by strongly coupled field theories. In the case of the plasmas produced in collisions at the RHIC facility (including in the beam energy scans), it is known how to deal with this problem: one has to take into account the large angular momenta generated in these plasmas, and the effects of the baryonic chemical potential. But this does not work for the plasmas produced in peripheral collisions at the LHC. However, these results neglect some (less significant) aspects of bulk physics; could it be that the problem is resolved by taking into account these lower-order effects? Here we use a bulk dilatonic field (fully compatible with boundary data, as well as with the asymptotically AdS character of the bulk geometry) as a model of these effects, and show that this is unlikely to be the solution. Thus, the existence of a consistent holographic description of the most extreme LHC plasmas remains open to question.
Gluon effects on the equation of state of color superconducting strange stars
NASA Astrophysics Data System (ADS)
Ferrer, E. J.; de la Incera, V.; Paulucci, L.
2015-08-01
Compact astrophysical objects are a window for the study of strongly interacting nuclear matter given the conditions in their interiors, which are not reproduced in a laboratory environment. Much has been debated about their composition with possibilities ranging from a simple mixture of mostly protons and neutrons to deconfined quark matter. Recent observations on the mass of two pulsars, PSR J 1614 -2230 and PSR J 0348 +0432 , have posed a great restriction on their composition, since the equation of state must be hard enough to support masses of about at least two solar masses. The onset of quarks tends to soften the equation of state, but it can get substantially stiffer since in the high-dense medium a repulsive vector interaction channel is opened. Nevertheless, we show that once gluon effects are considered, the equation of state of strange stars formed by quark matter in the color-flavor-locked (CFL) phase of color superconductivity becomes softer decreasing the maximum stellar mass that can be reached. This may indicate that strange stars made entirely of CFL matter can only be favored if other interactions, as the one corresponding to the vector channel, are taken into consideration and are large enough.
Color path integral equation of state of the quark-gluon plasma at nonzero chemical potential
NASA Astrophysics Data System (ADS)
Filinov, V. S.; Bonitz, M.; Ivanov, Yu B.; Ilgenfritz, E.-M.; Fortov, V. E.
2015-04-01
Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for calculation of the thermodynamic properties of the QGP is developed. We show that the PIMC method can be used for calculations of the equation of state at zero and non-zero baryon chemical potential not only above but also below the QCD critical temperature. Our results agree with lattice QCD calculations based on a Taylor expansion around zero baryon chemical potential. In our approach the QGP partition function is presented in the form of a color path integral with a relativistic measure replacing the Gaussian one traditionally used in the Feynman-Wiener path integrals. A procedure of sampling color variables according to the SU(3) group Haar measure is used for integration over the color variables. We expect that this approach will be useful to predict additional properties of the QGP that are still unaccesible in lattice QCD.
Perturbative and nonperturbative aspects of jet quenching in near-critical quark-gluon plasmas
NASA Astrophysics Data System (ADS)
Xu, Jiechen
In this thesis, we construct two QCD based energy loss models to perform quantitative analysis of jet quenching observables in ultra-relativistic nucleus-nucleus collisions at RHIC and the LHC. We first build up a perturbative QCD based CUJET2.0 jet flavor tomography model that couples the dynamical running coupling DGLV opacity series to bulk data constrained relativistic viscous hydrodynamic backgrounds. It solves the strong heavy quark energy loss puzzle at RHIC and explains the surprising transparency of the quark-gluon plasma (QGP) at the LHC. The observed azimuthal anisotropy of hard leading hadrons requires a path dependent jet-medium coupling in CUJET2.0 that implies physics of nonperturbative origin. To explore the nonperturbative chromo-electric and chromo-magnetic structure of the strongly-coupled QGP through jet probes, we build up a new CUJET3.0 framework that includes in CUJET2.0 both Polyakov loop suppressed semi-QGP chromo-electric charges and emergent chromo-magnetic monopoles in the critical transition regime. CUJET3.0 quantitatively describes the anisotropic hadron suppression at RHIC and the LHC. More significantly, it provides a robust connection between the long wavelength ``perfect fluidity'' of the QGP and the short distance jet transport in the QGP. This framework paves the way for ``measuring'' both perturbative and nonperturbative properties of the QGP, and more importantly for probing color confinement through jet quenching.
A rotation/magnetism analogy for the quark-gluon plasma
NASA Astrophysics Data System (ADS)
McInnes, Brett
2016-10-01
In peripheral heavy ion collisions, the Quark-Gluon Plasma that may be formed often has a large angular momentum per unit energy. This angular momentum may take the form of (local) rotation. In many physical systems, rotation can have effects analogous to those produced by a magnetic field; thus, there is a risk that the effects of local rotation in the QGP might be mistaken for those of the large genuine magnetic fields which are also known to arise in these systems. Here we use the gauge-gravity duality to investigate this, and we find indeed that, with realistic parameter values, local rotation has effects on the QGP (at high values of the baryonic chemical potential) which are not only of the same kind as those produced by magnetic fields, but which can in fact be substantially larger. Furthermore, the combined effect of rotation and magnetism is to change the shape of the main quark matter phase transition line in an interesting way, reducing the magnitude of its curvature; again, local rotation contributes to this phenomenon at least as strongly as magnetism.
Quark-gluon plasma effects on hadrons in AdS/QCD
NASA Astrophysics Data System (ADS)
Bartz, Sean; Jacobson, Theodore
2016-09-01
The AdS/CFT correspondence has succeeded in describing qualitatively many features of non-perturbative QCD. An approach known as bottom-up AdS/QCD uses a dilaton field to break conformal symmetry, introducing confinement and describing well the features of hadronic spectra at zero temperature. Introducing a black hole into the AdS metric allows for the study of thermodynamic properties of QCD, mimicking the behavior of hadrons interacting with a hot, dense medium such as the quark-gluon plasma produced in heavy ion collisions. We present an improved AdS/QCD model for meson and glueball spectra at finite temperature and baryon chemical potential. The spectra match the experimental and lattice data qualitatively well at low temperature, but we also find some subtleties in connecting to the best zero-temperature models. We find a melting temperature for light mesons that is below the current estimates for the deconfinement temperature. Finally, we examine the melting and jet-quenching of heavy quarkonia, which more commonly act as probes of the QGP in heavy ion collisions.
What RHIC experiments and theory tell us about properties of quark-gluon plasma?
NASA Astrophysics Data System (ADS)
Shuryak, Edward
2005-03-01
This brief review summarizes the main experimental discoveries made at RHIC and then discusses their implications. The robust collective flow phenomena are well described by ideal hydrodynamics, with the equation of state (EoS) predicted by lattice simulations. However the transport properties turned out to be unexpected, with rescattering cross section one-to-two orders of magnitude larger than expected from perturbative QCD. These and other theoretical developments indicate that quark-gluon plasma (QGP) produced at RHIC, and probably in a wider temperature region T
Korteveg-de Vries solitons in a cold quark-gluon plasma
NASA Astrophysics Data System (ADS)
Fogaça, D. A.; Navarra, F. S.; Ferreira Filho, L. G.
2011-09-01
The relativistic heavy ion program developed at RHIC and now at LHC motivated a deeper study of the properties of the quark-gluon plasma (QGP) and, in particular, the study of perturbations in this kind of plasma. We are interested on the time evolution of perturbations in the baryon and energy densities. If a localized pulse in baryon density could propagate throughout the QGP for long distances preserving its shape and without loosing localization, this could have interesting consequences for relativistic heavy ion physics and for astrophysics. A mathematical way to prove that this can happen is to derive (under certain conditions) from the hydrodynamical equations of the QGP a Korteveg-de Vries (KdV) equation. The solution of this equation describes the propagation of a KdV soliton. The derivation of the KdV equation depends crucially on the equation of state (EOS) of the QGP. The use of the simple MIT bag model EOS does not lead to KdV solitons. Recently we have developed an EOS for the QGP which includes both perturbative and nonperturbative corrections to the MIT one and is still simple enough to allow for analytical manipulations. With this EOS we were able to derive a KdV equation for the cold QGP.
Heller, Michal P; Janik, Romuald A; Spaliński, Michał; Witaszczyk, Przemysław
2014-12-31
Relativistic hydrodynamics simulations of quark-gluon plasma play a pivotal role in our understanding of heavy ion collisions at RHIC and LHC. They are based on a phenomenological description due to Müller, Israel, Stewart (MIS) and others, which incorporates viscous effects and ensures a well-posed initial value problem. Focusing on the case of conformal plasma we propose a generalization which includes, in addition, the dynamics of the least damped far-from-equilibrium degree of freedom found in strongly coupled plasmas through the AdS/CFT correspondence. We formulate new evolution equations for general flows and then test them in the case of N=4 super Yang-Mills plasma by comparing their solutions alongside solutions of MIS theory with numerical computations of isotropization and boost-invariant flow based on holography. In these tests the new equations reproduce the results of MIS theory when initialized close to the hydrodynamic stage of evolution, but give a more accurate description of the dynamics when initial conditions are set in the preequilibrium regime.
Electrical conductivity of quark-gluon plasma in strong magnetic fields
NASA Astrophysics Data System (ADS)
Hattori, Koichi; Satow, Daisuke
2016-12-01
We compute the electrical conductivity of quark-gluon plasma in a strong magnetic field B with quantum field theory at finite temperature using the lowest Landau level approximation. We provide the one-loop result arising from 1-to-2 scattering processes of which the kinematics are satisfied by the (1 +1 )-dimensional fermion dispersion relation. Because of the chirality conservation, the conductivity diverges in the massless limit and is sensitive to the value of the current quark mass. As a result, we find that the conductivity along the direction of the magnetic field is quite large compared with the value at B =0 , mainly because of the small value of the current quark mass. We show that the resummation of the ladder diagrams for the current-current correlator gives rise to only subleading contributions beyond the leading-log order and thus verify our one-loop result at the leading-log accuracy. We also discuss possible implications for the relativistic heavy-ion collisions.
ConnesFusionTensorProduct/Photon GluonFusion in Mitochondria
NASA Astrophysics Data System (ADS)
Wh-Maksoed, Prodi Of Physics Ui, Depok 16415-Indonesia; Ssi, Wh-Maksoed
2016-05-01
As in AJ Wassermann distinguished of classical invariant theory & quantum invariant theory subfactor, in S. Palcoux:``From Neveu-Schwarz Subfactors & Connes Fusion'' described the subfactor theory & Witt-algebra whereas Andreas Thom's explanation about ConnesFusionTensorProduct/CFTP related Connes fusion to composition of homomorphism (i). classical tensor product O-X adds the changes,(ii). Relative tensor product H-X preserve the changes. For photonGluonFusion/PGF defined:''photon is the gauge boson of QED, the simplest of all boson'' devotes to CFT as ``quantum field theory which are invariant under conformal transformation & in 2D there are infinite dimensional algebra. Alain Connes states theirselves Connes fusion as ``associative tensor operation'' to be in coincidences with ``their dynamic behavior driven by the balance in mitochondrial fusion & fission (Carveney, 2007) from Peter Alexander Williams: ``Retinal neuronal remodeling in a model of Optic Atrophy'', Dec, 2011. Great acknowledged to the VicePresident of the R.I, HE.Mr. Drs. M. JUSUF KALLA.
Monte Carlo study of Quark Gluon Plasma using photon jet observables
NASA Astrophysics Data System (ADS)
Xing, Tian
2016-09-01
Relativistic heavy ion collisions create an exotic state of deconfined, nuclear matter called quark gluon plasma (QGP), providing an opportunity to study the strong interaction. In some particularly hard scattered events, a parton with high transverse momentum (pT) interacts with this medium before fragmenting into a spray of particles, called a jet. Jet properties of heavy ion collisions can be modified relative to expectations from pp collisions; this effect is called jet quenching. Measurement of the jet internal structure can provide information about this effect and about the medium itself. On the other hand, studying systems whose jets are recoiled against photons coming from an initial scattering offers a way to calibrate the momentum of the modified jet. Since photons do not carry color charge, they escape the QGP with their initial momentum intact. On this poster, results using the Monte Carlo event generators Pythia and JEWEL will be presented for fragmentation functions and jet suppression from photon-jet events, alongside experimental data from CMS and ATLAS at a center of mass energy of 2.76 TeV. Predictions are also presented for lead-lead collisions at a center of mass energy of 5.02 TeV.
Complex suppression patterns distinguish between major energy loss effects in Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Djordjevic, Magdalena
2016-12-01
Interactions of high momentum partons with Quark-Gluon Plasma created in relativistic heavy-ion collisions provide an excellent tomography tool for this new form of matter. Recent measurements for charged hadrons and unidentified jets at the LHC show an unexpected flattening of the suppression curves at high momentum, exhibited when either momentum or the collision centrality is changed. Furthermore, a limited data available for B probes indicate a qualitatively different pattern, as nearly the same flattening is exhibited for the curves corresponding to two opposite momentum ranges. We here show that the experimentally measured suppression curves are well reproduced by our theoretical predictions, and that the complex suppression patterns are due to an interplay of collisional, radiative energy loss and the dead-cone effect. Furthermore, for B mesons, we predict that the uniform flattening of the suppression indicated by the limited dataset is in fact valid across the entire span of the momentum ranges, which will be tested by the upcoming experiments. Overall, the study presented here, provides a rare opportunity for pQCD theory to qualitatively distinguish between the major energy loss mechanisms at the same (nonintuitive) dataset.
Shear viscosity of the quark-gluon plasma in a kinetic theory approach
Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.
2014-05-09
One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound η/s=1/4π for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed η/s and have a comparison with physical observables like elliptic flow.
Obtaining Public Records: Reporter Guide
ERIC Educational Resources Information Center
Hammond, Betsy
2013-01-01
Obtaining public records is essential to covering public education. Fortunately, the law is on the side of reporters: Public agencies generally must disclose their records to the public and to the media--with important exceptions. Public agencies are often reluctant to hand over records, however, even when the law clearly says they should.…
Employment Obtaining and Business Starting
ERIC Educational Resources Information Center
Lan, Jian
2009-01-01
The implementation of business starting education in higher vocational colleges is of important and realistic meanings for cultivating advanced technology application-type talents and for releasing the employment obtaining pressure of higher vocational students. Based on the analysis on the employment situation of higher vocational graduates, this…
Obtaining consent for eye donation.
Diamond, G A; Campion, M; Mussoline, J F; D'Amico, R A
1987-02-15
We prospectively studied 100 consecutive deaths at St. Vincent's Hospital and Medical Center in New York City for possible eye donation. Fifty-two patients were unsuitable mainly because of medical contraindications and age at death. Of the 48 suitable candidates, 21 pairs (44%) of eyes were obtained. Sixteen of the 42 eyes (38%) were used for transplantation. Projection of the number of corneas obtainable for transplant in New York City were calculated. The figures indicated that the three-month waiting list of the New York Eye-Bank for Sight Restoration, Inc., could be eradicated if hospitals were able to get seven donors from every 100 deaths suitable for donation, a rate only 16% of that realized in this study.
Bridging soft-hard transport properties of quark-gluon plasmas with CUJET3.0
Xu, Jiechen; Liao, Jinfeng; Gyulassy, Miklos
2016-02-01
A new model (CUJET3.0) of jet quenching in nuclear collisions coupled to bulk data constrained (VISH2+1D) viscous hydrodynamic backgrounds is constructed by generalizing the perturbative QCD based (CUJET2.0) model to include two complementary non-perturbative chromodynamical features of the QCD con_nement cross-over phase transition near Tc ≈ 160 MeV: (1) the suppression of quark and gluon chromo-electric-charged (cec) degrees of freedom and (2) the emergence of chromo-magnetic-monopole (cmm) degrees of freedom. Such a semi Quark Gluon Monopole Plasma (sQGMP) microscopic scenario is tested by comparing predictions of the leading hadron nuclear modification factors, R_{AA}^{h} (pT > 10GeV=c;√s), and their azimuthal elliptic asymmetry v_{2}^{h} (pT > 10GeV=c;√s) with available data on h =π, D;B jet fragments from nuclear collisions at RHIC (√s = 0.2 ATeV) and LHC(√s = 2.76 ATeV). The cmm degrees of freedom in the sQGMP model near T_{c} are shown to solve robustly the long standing R_{AA} vs v_{2} puzzle by predicting a maximum of the jet quenching parameter field g(E; T)/T^{3} near T_{c}. The robustness of CUJET3.0 model to a number of theoretical uncertainties is critically tested. Moreover the consistency of jet quenching with observed bulk perfect uidity is demonstrated by extrapolating the sQGMP qˆ down to thermal energy E ~ 3T scales and showing that the sQGMP shear viscosity to entropy density ratio η/s ≈ T^{3}/qˆ falls close to the unitarity bound, 1/4π, in the range (1–2)Tc. Detailed comparisons of the CUJET2.0 and CUJET3.0 models reveal the fact that remarkably different qˆ(T) dependence could be consistent with the same R_{AA} data and could only be distinguished by anisotropy observables. Furthermore, these findings demonstrate clearly the inadequacy of focusing on the jet path averaged quantity as the only relevant medium property to
The critical indices of the quark gluon bags with surface tension model with tricritical endpoint
NASA Astrophysics Data System (ADS)
Ivanytskyi, A. I.
2012-04-01
The critical indices α', β, γ' and δ of the quark gluon bags with surface tension model with the tricritical endpoint are calculated as functions of the usual parameters of this model and two newly introduces parameters (indices) in order to perform a thorough comparison with the critical exponents of other models. It is shown that for the newly introduced indices χ=0 and ξT⩽1 there is a branch of solutions for which the critical exponents of the present model and the statistical multifragmentation model coincide, otherwise these models have different critical exponents. The critical exponents α', β, γ' and δ of ordinary liquids and 3-dimensional Ising model are reproduced by several sets of the model parameters, but the resulting range of the Fisher exponent τ is rather narrow and lies between 20/11 and 2. The scaling relations for the found critical exponents are verified and it is demonstrated that for the standard definition of the index α' the Fisher and Griffiths scaling inequalities are not fulfilled for some values of the model parameters, whereas the Liberman scaling inequality is always obeyed. It is also shown that the specially defined index αs' recovers the scaling relations. A thorough analysis of the critical exponents obeying the scaling relations along with the condition αs'>-β is performed. The found solutions enable us to reproduce the critical exponents of the 3-dimensional O(4) spin model and to show that for this case the exponent τ falls almost in the same range of values as for the ordinary liquids.
Dilepton production rate in a hot and magnetized quark-gluon plasma
NASA Astrophysics Data System (ADS)
Sadooghi, N.; Taghinavaz, F.
2017-01-01
The differential multiplicity of dileptons in a hot and magnetized quark-gluon plasma, ΔB ≡ dNB /d4 xd4 q, is derived from first principles. The constant magnetic field B is assumed to be aligned in a fixed spatial direction. It is shown that the anisotropy induced by the B field is mainly reflected in the general structure of photon spectral density function. This is related to the imaginary part of the vacuum polarization tensor, Im [Πμν ] , which is derived in a first order perturbative approximation. As expected, the final analytical expression for ΔB includes a trace over the product of a photonic part, Im [Πμν ] , and a leptonic part, Lμν. It is shown that ΔB consists of two parts, ΔB∥ and ΔB⊥ , arising from the components (μ , ν) =(∥ , ∥) and (μ , ν) =(⊥ , ⊥) of Im [Πμν ] and Lμν. Here, the transverse and longitudinal directions are defined with respect to the direction of the B field. Combining ΔB∥ and ΔB⊥, a novel anisotropy factor νB is introduced. Using the final analytical expression of ΔB, the possible interplay between the temperature T and the magnetic field strength eB on the ratio ΔB /Δ0 and νB is numerically studied. Here, Δ0 is the Born approximated dilepton multiplicity in the absence of external magnetic fields. It is, in particular, shown that for each fixed T and B, in the vicinity of certain threshold energies of virtual photons, ΔB ≫Δ0 and ΔB⊥ ≫ ΔB∥ . The latter anisotropy may be interpreted as one of the microscopic sources of the macroscopic anisotropies, reflecting themselves, e.g., in the elliptic asymmetry factor v2 of dileptons.
Gluon and charm content of the {eta}{sup {prime}} meson and instantons
Shuryak, E.V. |; Zhitnitsky, A.R. |
1998-02-01
Motivated by recent CLEO measurements of the B{r_arrow}{eta}{sup {prime}}K decay, we evaluate the gluon and charm content of the {eta}{sup {prime}} meson using the interacting instanton liquid model of the QCD vacuum. Our main result is {l_angle}0{vert_bar}g{sup 3}f{sup abc}G{sub {mu}{nu}}{sup a}{tilde G}{sub {nu}{alpha}}{sup b}G{sub {alpha}{mu}}{sup c}{vert_bar}{eta}{sup {prime}}{r_angle}={minus}(2.3{endash}3.3) GeV{sup 2}{times}{l_angle}0{vert_bar}g{sup 2}G{sub {mu}{nu}}{sup a}{tilde G}{sub {mu}{nu}}{sup a}{vert_bar}{eta}{sup {prime}}{r_angle}. It is very large due to the strong field of small-size instantons. We show that it provides quantitative explanations of the CLEO data on the B{r_arrow}{eta}{sup {prime}}K decay rate (as well as the inclusive process B{r_arrow}{eta}{sup {prime}}+X), via a virtual Cabibbo-unsuppressed decay into a {bar c}c pair which then becomes {eta}{sup {prime}}. If so, a significant charm component may be present in other hadrons also: We briefly discuss the contribution of the charmed quark to the {ital polarized} deep-inelastic scattering on a proton. {copyright} {ital 1998} {ital The American Physical Society}
Physics of the nucleon sea quark distributions
Vogt, R.
2000-03-10
Sea quark distributions in the nucleon have naively been expected to be generated perturbatively by gluon splitting. In this case, there is no reason for the light quark and anti-quark sea distributions to be different. No asymmetries in the strange or heavy quark sea distributions are predicted in the improved parton model. However,recent experiments have called these naive expectations into question. A violation of the Gottfried sum rule has been measured in several experiments, suggesting that (bar u) < (bar d) in the proton. Additionally, other measurements, while not definitive, show that there may be an asymmetry in the strange and anti-strange quark sea distributions. These effects may require nonperturbative explanations. In this review we first discuss the perturbative aspects of the sea quark distributions. We then describe the experiments that could point to nonperturbative contributions to the nucleon sea. Current phenomenological models that could explain some of these effects are reviewed.
How To Obtain Aerial Photographs
,
1999-01-01
The U.S. Geological Survey (USGS) maintains an informational data base of aerial photographic coverage of the United States and its territories that dates back to the 1940?s. This information describes photographic projects from the USGS, other Federal, State, and local government agencies, and commercial firms. The pictures on this page show a part of a standard 9- by 9-inch photograph and the results obtained by enlarging the original photograph two and four times. Compare the size of the Qualcomm Stadium, Jack Murphy Field, in San Diego, Calif, and the adjacent parking lot and freeways shown at the different scales. USGS Earth Science Information Center (ESIC) representatives will assist you in locating and ordering photographs. Please submit the completed checklist and a marked map showing your area of interest to any ESIC.
Dai, Ling -Yun; Kang, Zhong -Bo; Prokudin, Alexei; ...
2015-12-22
Here, we study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. We concentrate on the contribution from the photon-gluon fusion channel at O(αem2αs), where three-gluon correlation functions play a major role within the twist-3 collinear factorization formalism. We establish the correspondence between such a formalism with three-gluon correlation functions and the usual transverse momentum-dependent (TMD) factorization formalism at moderate hadron transverse momenta. We derive the coefficient functions used in the usual TMD evolution formalism related to the quark Sivers function expansion in terms of the three-gluon correlation functions. We further perform the next-to-leading order calculation for themore » transverse momentum-weighted spin-dependent differential cross section and identify the off-diagonal contribution from the three-gluon correlation functions to the QCD collinear evolution of the twist-3 Qiu-Sterman function.« less
Dai, Ling -Yun; Kang, Zhong -Bo; Prokudin, Alexei; Vitev, Ivan
2015-12-22
Here, we study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. We concentrate on the contribution from the photon-gluon fusion channel at O(α_{em}^{2}α_{s}), where three-gluon correlation functions play a major role within the twist-3 collinear factorization formalism. We establish the correspondence between such a formalism with three-gluon correlation functions and the usual transverse momentum-dependent (TMD) factorization formalism at moderate hadron transverse momenta. We derive the coefficient functions used in the usual TMD evolution formalism related to the quark Sivers function expansion in terms of the three-gluon correlation functions. We further perform the next-to-leading order calculation for the transverse momentum-weighted spin-dependent differential cross section and identify the off-diagonal contribution from the three-gluon correlation functions to the QCD collinear evolution of the twist-3 Qiu-Sterman function.
NASA Astrophysics Data System (ADS)
Kumar, Yogesh; Singh, S. Somorendro
2016-07-01
We extend the previous study of dilepton production using [S. Somorendro Singh and Y. Kumar, Can. J. Phys. 92 (2014) 31] based on a simple quasiparticle model of quark-gluon plasma (QGP). In this model, finite value of quark mass uses temperature dependent chemical potential the so-called Temperature Dependent Chemical Potential Quark Mass (TDCPQM). We calculate dilepton production in the relevant range of mass region. It is observed that the production rate is marginally enhanced from the earlier work. This is due to the effect of TDCPQM and its effect is highly significant in the production of dilepton.
Niemi, H; Denicol, G S; Huovinen, P; Molnár, E; Rischke, D H
2011-05-27
We investigate the influence of a temperature-dependent shear viscosity over entropy density ratio η/s on the transverse momentum spectra and elliptic flow of hadrons in ultrarelativistic heavy-ion collisions. We find that the elliptic flow in √S(NN)=200 GeV Au+Au collisions at RHIC is dominated by the viscosity in the hadronic phase and in the phase transition region, but largely insensitive to the viscosity of the quark-gluon plasma (QGP). At the highest LHC energy, the elliptic flow becomes sensitive to the QGP viscosity and insensitive to the hadronic viscosity.
Higgs boson gluon-fusion production beyond threshold in N^{3}LO QCD
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard
2015-03-18
In this study, we compute the gluon fusion Higgs boson cross-section at N^{3}LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N^{3}LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N^{3}LO in perturbative QCD.
NASA Astrophysics Data System (ADS)
Bonetti, Marco; Melnikov, Kirill; Tancredi, Lorenzo
2017-03-01
We compute the two-loop electroweak correction to the production of the Higgs boson in gluon fusion to higher orders in the dimensional-regularization parameter ε = (d - 4) / 2. We employ the method of differential equations augmented by the choice of a canonical basis to compute the relevant integrals and express them in terms of Goncharov polylogarithms. Our calculation provides useful results for the computation of the NLO mixed QCD-electroweak corrections to gg → H and establishes the necessary framework towards the calculation of the missing three-loop virtual corrections.
SYSTEMATIC STUDIES OF HEAVY ION COLLISIONS TO SEARCH FOR QUARK-GLUON PLASMA
Fuqiang Wang
2007-11-29
This is the final technical report for DOE Outstanding Junior Investigator (OJI) Award, 'Systematic Studies of Heavy Ion Collisions to Search for Quark-Gluon Plasma', grant DE-FG02-02ER41219, Principal Investigator (PI) Fuqiang Wang. The research under the grant was divided into two phases. The first concentrated on systematic studies of soft hadron production at low transverse momentum (p{sub T}), in particular the production of (anti-)baryon and strangeness in heavy ion collisions at RHIC energies. The second concentrated on measurements of di-hadron and multi-hadron jet-correlations and investigations of medium response to jets. The research was conducted at the Relativistic Heavy-Ion Collider (RHIC) at BNL with the Solenoidal Tracker At RHIC (STAR) experiment. The total grant is $214,000. The grant established a PC farm solely used for this research. The PC farm consists of 8 nodes with a total of 16 CPUs and 3 disk servers of total 2 TB shared storage. The current balance of the grant is $19,985. The positive balance is because an initial purchase of $22,600 for the PC farm came out of the PI's start-up fund due to the lateness of the award. The PC farm is an integral part of the Purdue Physics Department's computer cluster. The grant supported two Ph.D. graduate students. Levente Molnar was supported from July 2002 to December 2003, and worked on soft hadron production. His thesis title is Systematics of Identified Particle Production in pp, d-Au and Au-Au Collisions at RHIC Energies. He graduated in 2006 and now is a Postdoctoral fellow at INFN Sezione di Bari, Italy working on the ALICE experiment at the LHC. Jason Ulery was supported from January 2004 to July 2007. His thesis title is Two- and Three-Particle Jet-Like Correlations. He defended his thesis in October 2007 and is moving to Frankfurt University, Germany to work on the ALICE experiment at the LHC. The research by this grant resulted in 7 journal publications (2 PRL, 1 PLB, 1 PRC, 2 submitted and
Search for a heavy vector boson decaying to two gluons in pp̄ collisions at √s=1.96 TeV
Aaltonen, T.; Adelman, J.; Álvarez González, B.; ...
2012-12-05
We present a search for a new heavy vector boson Z' that decays to gluons. Decays to on-shell gluons are suppressed, leading to a dominant decay mode of Z'→g*g. We study the case where the off-shell gluon g* converts to a pair of top quarks, leading to a final state of tt¯g. In a sample of events with exactly one charged lepton, large missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb⁻¹ collected by the CDF II detector, we find the data to be consistent with the standard model. We set upper limitsmore » on the production cross section times branching ratio of this chromophilic Z' at 95% confidence level from 300 to 40 fb for Z' masses ranging from 400 to 1000 GeV/c², respectively.« less
Search for a heavy vector boson decaying to two gluons in pp̄ collisions at √s=1.96 TeV
Aaltonen, T.; Adelman, J.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d’Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell’Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d’Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D’Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khader, M.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Rao, K.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti, P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner, R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yen, M.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.; Zhou, C.; Zucchelli, S.
2012-12-05
We present a search for a new heavy vector boson Z' that decays to gluons. Decays to on-shell gluons are suppressed, leading to a dominant decay mode of Z'→g*g. We study the case where the off-shell gluon g* converts to a pair of top quarks, leading to a final state of tt¯g. In a sample of events with exactly one charged lepton, large missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb⁻¹ collected by the CDF II detector, we find the data to be consistent with the standard model. We set upper limits on the production cross section times branching ratio of this chromophilic Z' at 95% confidence level from 300 to 40 fb for Z' masses ranging from 400 to 1000 GeV/c², respectively.
Rosenberg, L.J.
1985-11-01
We have made a high statistics study of QCD jets produced in e/sup +/e/sup -/ annihilations at ..sqrt..s of 29 GeV and observed in the MAC detector located at the PEP storage ring at SLAC. The MAC detector uses calorimetry and provides a homogeneous response over much of its 98% . 4..pi.. sr instrumented solid angle. A data sample of well reconstructed hadronic events was selected by requiring that E/sub vis/ in the calorimeters be near ..sqrt..s, and almost all the energy be deposited in the central calorimeters. Fits of the jet transverse energy flow are made to the data using String (STR) model and several types of Independent Jet (IJM) model hypotheses, where ..alpha../sub s/, the strong coupling constant, and sigma/sub q/, the width of the secondary quark P/sub perpendicular/ distribution, are free parameters. The fits to O(..alpha../sub s//sup 2/ using MS-bar renormalization yield ..alpha../sub s/ approx.0.17 with the STR hypothesis, and ..alpha../sub s/ approx.0.12 with the various IJM hypotheses. The correlations between ..alpha../sub s/ and sigma/sub q/ are examined. Detailed comparisons were made with other experimental results. The energy flow projected onto the event plane of 3-jet events selected from the above data sample was studied. The data shows an asymmetric energy flow around the thin jet. Such an asymmetry was predicted by the STR model, and a cluster model (Webber) incorporating soft gluon interference. The various IJM models show no such asymmetry. We associate this asymmetry with coherence effects during hadronization. 106 refs., 58 figs., 18 tabs.
NASA Technical Reports Server (NTRS)
Takahashi, Y.; Eby, P. B.
1985-01-01
Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.
Obtaining the metric of our Universe
NASA Astrophysics Data System (ADS)
Jacobs, Mark W.; Linder, Eric V.; Wagoner, Robert V.
1992-05-01
We formulate a method for solving the gravitational field equations for perturbations to a Friedmann-Robertson-Walker metric, which does not depend on any kind of averaging procedure or make any a priori assumptions about the magnitude of fluctuations in the matter variables. We present a Green's function for obtaining the effective potential which characterizes the metric perturbations directly from the (possibly large) density fluctuations, and describe the application to astrophysical observations, for example, the angular-diameter distance-versus-redshift relation. The results do not assume a particular model for the formation of structure in the matter distribution, and are valid everywhere in our Universe outside of strong-field regions (e.g., black holes).
Groote, S.; Koerner, J. G.
2009-08-01
We determine the O({alpha}{sub s}) radiative corrections to polarized top quark pair production in e{sup +}e{sup -} annihilations with a specified gluon energy cut. We write down fully analytical results for the unpolarized and polarized O({alpha}{sub s}) cross sections e{sup +}e{sup -}{yields}tt(G) and e{sup +}e{sup -}{yields}tt{sup {up_arrow}}(G) including their polar orientation dependence relative to the beam direction. In the soft-gluon limit we recover the usual factorizing form known from the soft-gluon approximation. In the limit when the gluon energy cut takes its maximum value we recover the totally inclusive unpolarized and polarized cross sections calculated previously. We provide some numerical results on the cutoff dependence of the various polarized and unpolarized cross sections and discuss how the exact results numerically differ from the approximate soft-gluon results.
Obtaining information by dynamic (effortful) touching
Turvey, M. T.; Carello, Claudia
2011-01-01
Dynamic touching is effortful touching. It entails deformation of muscles and fascia and activation of the embedded mechanoreceptors, as when an object is supported and moved by the body. It is realized as exploratory activities that can vary widely in spatial and temporal extents (a momentary heft, an extended walk). Research has revealed the potential of dynamic touching for obtaining non-visual information about the body (e.g. limb orientation), attachments to the body (e.g. an object's height and width) and the relation of the body both to attachments (e.g. hand's location on a grasped object) and surrounding surfaces (e.g. places and their distances). Invariants over the exploratory activity (e.g. moments of a wielded object's mass distribution) seem to ground this ‘information about’. The conception of a haptic medium as a nested tensegrity structure has been proposed to express the obtained information realized by myofascia deformation, by its invariants and transformations. The tensegrity proposal rationalizes the relative indifference of dynamic touch to the site of mechanical contact (hand, foot, torso or probe) and the overtness of exploratory activity. It also provides a framework for dynamic touching's fractal nature, and the finding that its degree of fractality may matter to its accomplishments. PMID:21969694
Uncertainties in obtaining high reliability from stress-strength models
NASA Technical Reports Server (NTRS)
Neal, Donald M.; Matthews, William T.; Vangel, Mark G.
1992-01-01
There has been a recent interest in determining high statistical reliability in risk assessment of aircraft components. The potential consequences are identified of incorrectly assuming a particular statistical distribution for stress or strength data used in obtaining the high reliability values. The computation of the reliability is defined as the probability of the strength being greater than the stress over the range of stress values. This method is often referred to as the stress-strength model. A sensitivity analysis was performed involving a comparison of reliability results in order to evaluate the effects of assuming specific statistical distributions. Both known population distributions, and those that differed slightly from the known, were considered. Results showed substantial differences in reliability estimates even for almost nondetectable differences in the assumed distributions. These differences represent a potential problem in using the stress-strength model for high reliability computations, since in practice it is impossible to ever know the exact (population) distribution. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability.
Associated production of a KK-graviton with a Higgs boson via gluon fusion at the LHC
NASA Astrophysics Data System (ADS)
Shivaji, Ambresh; Mitra, Subhadip; Agrawal, Pankaj
2012-03-01
In order to solve the hierarchy problem, several extra-dimensional models have received considerable attention. We have considered a process where a Higgs boson is produced in association with a KK-graviton ( G KK) at the LHC. At the leading order, this process occurs through the gluon fusion mechanism gg→ hG KK via a quark loop. We compute the cross section and examine some features of this process in the ADD model. We find that the quark in the loop does not decouple in the large quark-mass limit just as in the case of gg→ h process. We compute the cross section of this process for the case of the RS model also. We examine the feasibility of this process being observed at the LHC.
Energy dependence of dissociative J/ψ photoproduction as a signature of gluon saturation at the LHC
NASA Astrophysics Data System (ADS)
Cepila, J.; Contreras, J. G.; Tapia Takaki, J. D.
2017-03-01
We have developed a model in which the quantum fluctuations of the proton structure are characterised by hot spots, whose number grows with decreasing Bjorken-x. Our model reproduces the F2 (x ,Q2) data from HERA at the relevant scale, as well as the exclusive and dissociative J / ψ photoproduction data from H1 and ALICE. Our model predicts that for Wγp ≈ 500 GeV, the dissociative J / ψ cross section reaches a maximum and then decreases steeply with energy, which is in qualitatively good agreement to a recent observation that the dissociative J / ψ background in the exclusive J / ψ sample measured in photoproduction by ALICE decreases as energy increases. Our prediction provides a clear signature for gluon saturation at LHC energies.
Production and elliptic flow of dileptons and photons in a matrix model of the quark-gluon plasma.
Gale, Charles; Hidaka, Yoshimasa; Jeon, Sangyong; Lin, Shu; Paquet, Jean-François; Pisarski, Robert D; Satow, Daisuke; Skokov, Vladimir V; Vujanovic, Gojko
2015-02-20
We consider a nonperturbative approach to the thermal production of dileptons and photons at temperatures near the critical temperature in QCD. The suppression of colored excitations at low temperature is modeled by including a small value of the Polyakov loop, in a "semi"-quark-gluon plasma (QGP). Comparing the semi-QGP to the perturbative QGP, we find a mild enhancement of thermal dileptons. In contrast, to leading logarithmic order in weak coupling there are far fewer hard photons from the semi-QGP than the usual QGP. To illustrate the possible effects on photon and dilepton production in heavy-ion collisions, we integrate the rate with a simulation using ideal hydrodynamics. Dileptons uniformly exhibit a small flow, but the strong suppression of photons in the semi-QGP tends to weight the elliptical flow of photons to that generated in the hadronic phase.
Das, Santosh K.; Alam, Jan-e; Mohanty, Payal
2010-07-15
The drag and diffusion coefficients of charm and bottom quarks propagating through quark gluon plasma (QGP) have been evaluated for conditions relevant to nuclear collisions at the Large Hadron Collider (LHC). The dead cone and Landau-Pomeronchuk-Migdal (LPM) effects on radiative energy loss of heavy quarks have been considered. Both radiative and collisional processes of energy loss are included in the effective drag and diffusion coefficients. With these effective transport coefficients, we solve the Fokker-Plank (FP) equation for the heavy quarks executing Brownian motion in the QGP. The solution of the FP equation has been used to evaluate the nuclear suppression factor, R{sub AA}, for the nonphotonic single-electron spectra resulting from the semileptonic decays of hadrons containing charm and bottom quarks. The effects of mass on R{sub AA} have also been highlighted.
Product Distributions for Distributed Optimization. Chapter 1
NASA Technical Reports Server (NTRS)
Bieniawski, Stefan R.; Wolpert, David H.
2004-01-01
With connections to bounded rational game theory, information theory and statistical mechanics, Product Distribution (PD) theory provides a new framework for performing distributed optimization. Furthermore, PD theory extends and formalizes Collective Intelligence, thus connecting distributed optimization to distributed Reinforcement Learning (FU). This paper provides an overview of PD theory and details an algorithm for performing optimization derived from it. The approach is demonstrated on two unconstrained optimization problems, one with discrete variables and one with continuous variables. To highlight the connections between PD theory and distributed FU, the results are compared with those obtained using distributed reinforcement learning inspired optimization approaches. The inter-relationship of the techniques is discussed.
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.
String effects and the distribution of the glue in static mesons at finite temperature
Bakry, A. S.; Leinweber, D. B.; Moran, P. J.; Williams, A. G.; Sternbeck, A.
2010-11-01
The distribution of the gluon action density in mesonic systems is investigated at finite temperature. The simulations are performed in quenched QCD for two temperatures below the deconfinement phase. Unlike the gluonic profiles displayed at T=0, the action-density isosurfaces display a prolate-spheroid-like shape. The curved width profile of the flux tube is found to be consistent with the prediction of the free bosonic string model at large distances.
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.
Momentum distributions of strange and anti-strange quarks in the proton
NASA Astrophysics Data System (ADS)
Hansen, Chase; Raschko, David; Netzel, Greg
2013-10-01
Strangeness in the proton has been confirmed by experiment. We are using the statistical method of Zhang et al., which explained the u - d asymmetry in the proton. We expand the model to include strange quarks, to explain the existence of strangeness in the proton. We used RAMBO in order to create a Bjorken-x distribution for the partons in the proton. We adjusted RAMBO to include the strange quark mass. In order to suppress the transitions to states that include s - s pairs, we calculate energy distributions for the gluons and allow gluons to split into s - s pairs only if the gluon is above the energy threshold of twice the mass of a strange quark. We expand our view to include the meson cloud model, attempting a different approach at explaining strangeness in the proton. After Q2 evolution, we compare our calculations of strangeness probability and S+ (x) to HERMES and ATLAS data, as well as global parton distribution fits. Supported in part by NSF Grants No. 0855656 and 1205686.
Bioactive glass nanoparticles obtained through sol-gel chemistry.
Lukowiak, Anna; Lao, Jonathan; Lacroix, Josephine; Nedelec, Jean-Marie
2013-07-28
Different sol-gel strategies based on the Stöber method are proposed enabling preparation of nanoparticles of SiO2-CaO bioactive glass with different size, narrow size distribution and good dispersion capability. Eu(3+)-doped glass nanoparticles with luminescent properties can also be obtained.
Pion Electromagnetic Form Factor in Virtuality Distribution Formalism
Radyushkin, Anatoly V.
2016-01-01
We discuss two applications of the {\\it Virtuality Distribution Amplitudes} (VDA) formalism developed in our recent papers. We start with an overview of the main properties of the pion distribution amplitude emphasizing the quantitative measures of its width, and possibility to access them through the pion transition form factor studies. We formulate the basic concepts of the VDA approach and introduce the pion {\\it transverse momentum distribution amplitude} (TMDA) which plays, in a covariant Lagrangian formulation, a role similar to that of the pion wave function in the 3-dimensional Hamiltonian light-front approach. We propose simple factorized models for soft TMDAs, and use them to describe existing data on the pion transition form factor, thus fixing the scale determining the size of the transverse-momentum effects. Finally, we apply the VDA approach to the one-gluon exchange contribution for the pion electromagnetic form factor. We observe a very late $Q^2 \\gtrsim 20$ GeV$^2$ onset of transition to the asymptotic pQCD predictions and show that in the $Q^2 \\lesssim 10$ GeV$^2$ region there is essentially no sensitivity to the shape of the pion distribution amplitude. Furthermore, the magnitude of the one-gluon exchange contribution in this region is estimated to be an order of magnitude below the Jefferson Lab data, thus leaving the Feynman mechanism as the only one relevant to the pion electromagnetic form factor behavior for accessible $Q^2$.
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.
Nouicer, R.
2016-03-28
This article reviews several important results from RHIC experiments and discusses their implications. They were obtained in a unique environment for studying QCD matter at temperatures and densities that exceed the limits wherein hadrons can exist as individual entities and raises to prominence the quark-gluon degrees of freedom. These findings are supported by major experimental observations via measuring of the bulk properties of particle production, particle ratios and chemical freeze-out conditions, and elliptic ow; followed by hard probe measurements: high-pT hadron suppression, dijet fragment azimuthal correlations, and heavy favor probes. These measurements are presented for particles of different species as a function of system sizes, collision centrality, and energy carried out in RHIC experiments. The results reveal that a dense, strongly-interacting medium is created in central Au + Au collisions at p sNN = 200 GeV at RHIC. This revelation of a new state of nuclear matter has also been observed in measurements at the LHC. Further, the IP-Glasma model coupled with viscous hydrodynamic models, which assumes the formation of a QGP, reproduces well the experimental ow results from Au + Au at p sNN = 200 GeV. This implies that the fluctuations in the initial geometry state are important and the created medium behaves as a nearly perfect liquid of nuclear matter because it has an extraordinarily low ratio of shear viscosity to entropy density, =s 0.12. However, these discoveries are far from being fully understood. Furthermore, recent experimental results from RHIC and LHC in small p + A, d + Au and 3He+Au collision systems provide brand new insight into the role of initial and final state effects. These have proven to be interesting and more surprising than originally anticipated; and could conceivably shed new light in our understanding of collective behavior in heavy-ion physics. Accordingly, the focus of the experiments at both facilities RHIC and the LHC
NASA Astrophysics Data System (ADS)
Nouicer, R.
2016-03-01
This article reviews several important results from RHIC experiments and discusses their implications. They were obtained in a unique environment for studying QCD matter at temperatures and densities that exceed the limits wherein hadrons can exist as individual entities and raises to prominence the quark-gluon degrees of freedom. These findings are supported by major experimental observations via measuring of the bulk properties of particle production, particle ratios and chemical freeze-out conditions, and elliptic flow; followed by hard probe measurements: high- pT hadron suppression, dijet fragment azimuthal correlations, and heavy-flavor probes. These measurements are presented for particles of different species as a function of system sizes, collision centrality, and energy carried out in RHIC experiments. The results reveal that a dense, strongly interacting medium is created in central Au+Au collisions at sqrt{s_{NN}} = 200 GeV at RHIC. This revelation of a new state of nuclear matter has also been observed in measurements at the LHC. Further, the IP-Glasma model coupled with viscous hydrodynamic models, which assumes the formation of a QGP, reproduces well the experimental flow results from Au+Au at sqrt{s_{NN}} = 200 GeV. This implies that the fluctuations in the initial geometry state are important and the created medium behaves as a nearly perfect liquid of nuclear matter because it has an extraordinarily low ratio of shear viscosity to entropy density, η/s≈ 0.12. However, these discoveries are far from being fully understood. Furthermore, recent experimental results from RHIC and LHC in small p+A, d+ Au and 3He+Au collision systems provide brand new insight into the role of initial and final state effects. These have proven to be interesting and more surprising than originally anticipated; and could conceivably shed new light in our understanding of collective behavior in heavy-ion physics. Accordingly, the focus of the experiments at both
Nouicer, R.
2016-03-28
This article reviews several important results from RHIC experiments and discusses their implications. They were obtained in a unique environment for studying QCD matter at temperatures and densities that exceed the limits wherein hadrons can exist as individual entities and raises to prominence the quark-gluon degrees of freedom. These findings are supported by major experimental observations via measuring of the bulk properties of particle production, particle ratios and chemical freeze-out conditions, and elliptic ow; followed by hard probe measurements: high-pT hadron suppression, dijet fragment azimuthal correlations, and heavy favor probes. These measurements are presented for particles of different species asmore » a function of system sizes, collision centrality, and energy carried out in RHIC experiments. The results reveal that a dense, strongly-interacting medium is created in central Au + Au collisions at p sNN = 200 GeV at RHIC. This revelation of a new state of nuclear matter has also been observed in measurements at the LHC. Further, the IP-Glasma model coupled with viscous hydrodynamic models, which assumes the formation of a QGP, reproduces well the experimental ow results from Au + Au at p sNN = 200 GeV. This implies that the fluctuations in the initial geometry state are important and the created medium behaves as a nearly perfect liquid of nuclear matter because it has an extraordinarily low ratio of shear viscosity to entropy density, =s 0.12. However, these discoveries are far from being fully understood. Furthermore, recent experimental results from RHIC and LHC in small p + A, d + Au and 3He+Au collision systems provide brand new insight into the role of initial and final state effects. These have proven to be interesting and more surprising than originally anticipated; and could conceivably shed new light in our understanding of collective behavior in heavy-ion physics. Accordingly, the focus of the experiments at both facilities RHIC and