Constraining the double gluon distribution by the single gluon distribution
NASA Astrophysics Data System (ADS)
Golec-Biernat, Krzysztof; Lewandowska, Emilia; Serino, Mirko; Snyder, Zachary; Staśto, Anna M.
2015-11-01
We show how to consistently construct initial conditions for the QCD evolution equations for double parton distribution functions in the pure gluon case. We use to momentum sum rule for this purpose and a specific form of the known single gluon distribution function in the MSTW parameterization. The resulting double gluon distribution satisfies exactly the momentum sum rule and is parameter free. We also study numerically its evolution with a hard scale and show the approximate factorization into product of two single gluon distributions at small values of x, whereas at large values of x the factorization is always violated in agreement with the sum rule.
The Weighted GMD Model for multiplicity distributions. Probing gluon production at LHC energies
NASA Astrophysics Data System (ADS)
Wang, W. Y.; Seah, S.; Setianegara, J.; Chan, A. H.; Oh, C. H.
2016-07-01
A new distribution, the Weighted GMD (WGMD) is obtained from the Generalised Multiplicity Distribution (GMD), describing charged-particle multiplicity distributions as the hadronisation products of quark and gluon branching with fluctuations in the initial gluon numbers produced from the collision. The WGMD is shown to describe charged-particle multiplicity distributions in pp collisions at the Large Hadron Collider (LHC), and the average initial gluon number is obtained for Poisson distributed gluon multiplicities.
The gluon Sivers distribution: Status and future prospects
Boer, Daniël; Lorcé, Cédric; Pisano, Cristian; Zhou, Jian
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.
Universality of Unintegrated Gluon Distributions at small x
Dominguez, Fabio; Marquet, Cyrille; Xiao, Bowen; Yuan, Feng
2011-01-04
We systematically study dijet production in various processes in the small-x limit and establish an effective kt-factorization for hard processes in a system with dilute probes scattering on a dense target. In the large-Nc limit, the unintegrated gluon distributions involved in different processes are shown to be related to two widely proposed ones: the Weizsacker-Williams gluon distribution and the dipole gluon distribution.
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.
NASA Astrophysics Data System (ADS)
Chandra, Vinod; Sreekanth, V.
2015-11-01
Viscous modifications to the thermal distributions of quark-antiquarks and gluons have been studied in a quasiparticle description of the quark-gluon-plasma medium created in relativistic heavy-ion collision experiments. The model is described in terms of quasipartons that encode the hot QCD medium effects in their respective effective fugacities. Both shear and bulk viscosities have been taken in to account in the analysis, and the modifications to thermal distributions have been obtained by modifying the energy-momentum tensor in view of the nontrivial dispersion relations for the gluons and quarks. The interactions encoded in the equation of state induce significant modifications to the thermal distributions. As an implication, the dilepton production rate in the q q ¯ annihilation process has been investigated. The equation of state is found to have a significant impact on the dilepton production rate along with the viscosities.
Color neutrality and the gluon distribution in a very large nucleus
NASA Astrophysics Data System (ADS)
Lam, C. S.; Mahlon, Gregory
2000-01-01
We improve the McLerran-Venugopalan model for the gluon distribution functions in very large nuclei by imposing the condition that the nucleons should be color neutral. We find that enforcing color neutrality cures the infrared divergences in the transverse coordinates which are present in the McLerran-Venugopalan model. Since we obtain well-defined expressions for the distribution functions, we are able to draw unambiguous conclusions about various features of the model. In particular, we show that the gluon distribution functions in the absence of quantum corrections behave as 1/xF to all orders in the coupling constant. Furthermore, our distribution functions exhibit saturation at small transverse momenta. The normalization of the distribution function we obtain is not arbitrary but specified in terms of the nucleon structure. We derive a sum rule for the integral of the gluon distribution function over transverse momenta, and show that the non-Abelian contributions serve only to modify the shape of the transverse momentum distribution. We obtain a relatively simple expression for the mean value of the transverse momentum-squared. The connection between the McLerran-Venugopalan model and the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation is discussed quantitatively. Finally, we illustrate our results in terms of a simple nuclear model due to Kovchegov.
QCD evolution of (un)polarized gluon TMDPDFs and the Higgs q T -distribution
NASA Astrophysics Data System (ADS)
Echevarria, Miguel G.; Kasemets, Tomas; Mulders, Piet J.; Pisano, Cristian
2015-07-01
We provide the proper definition of all the leading-twist (un)polarized gluon transverse momentum dependent parton distribution functions (TMDPDFs), by considering the Higgs boson transverse momentum distribution in hadron-hadron collisions and deriving the factorization theorem in terms of them. We show that the evolution of all the (un)polarized gluon TMDPDFs is driven by a universal evolution kernel, which can be resummed up to next-to-next-to-leading-logarithmic accuracy. Considering the proper definition of gluon TMDPDFs, we perform an explicit next-to-leading-order calculation of the unpolarized ( f {1/ g }), linearly polarized ( h {1/⊥ g }) and helicity ( g {1/L g }) gluon TMDPDFs, and show that, as expected, they are free from rapidity divergences. As a byproduct, we obtain the Wilson coefficients of the refactorization of these TMDPDFs at large transverse momentum. In particular, the coefficient of g {1/L g }, which has never been calculated before, constitutes a new and necessary ingredient for a reliable phenomenological extraction of this quantity, for instance at RHIC or the future AFTER@LHC or Electron-Ion Collider. The coefficients of f {1/ g } and h {1/⊥ g } have never been calculated in the present formalism, although they could be obtained by carefully collecting and recasting previous results in the new TMD formalism. We apply these results to analyze the contribution of linearly polarized gluons at different scales, relevant, for instance, for the inclusive production of the Higgs boson and the C-even pseudoscalar bottomonium state η b . Applying our resummation scheme we finally provide predictions for the Higgs boson q T -distribution at the LHC.
Gluon distribution functions and Higgs boson production at moderate transverse momentum
Sun Peng; Xiao Bowen; Yuan Feng
2011-11-01
We investigate the gluon distribution functions and their contributions to the Higgs boson production in pp collisions in the transverse momentum-dependent factorization formalism. In addition to the usual azimuthal symmetric transverse momentum-dependent gluon distribution, we find that the azimuthal correlated gluon distribution also contributes to the Higgs boson production. This explains recent findings on the additional contribution in the transverse momentum resummation for the Higgs boson production as compared to that for electroweak boson production processes. We further examine the small-x naive k{sub t}-factorization in the dilute region and find that the azimuthal correlated gluon distribution contribution is consistently taken into account. The result agrees with the transverse momentum-dependent factorization formalism. We comment on the possible breakdown of the naive k{sub t}-factorization in the dense medium region, due to the unique behaviors for the gluon distributions.
Gluon distribution functions and Higgs boson production at moderate transverse momentum
Sun P.; Yuan F.; Xiao, B.W.
2011-11-04
We investigate the gluon distribution functions and their contributions to the Higgs boson production in pp collisions in the transverse momentum-dependent factorization formalism. In addition to the usual azimuthal symmetric transverse momentum-dependent gluon distribution, we find that the azimuthal correlated gluon distribution also contributes to the Higgs boson production. This explains recent findings on the additional contribution in the transverse momentum resummation for the Higgs boson production as compared to that for electroweak boson production processes. We further examine the small-x naive kt-factorization in the dilute region and find that the azimuthal correlated gluon distribution contribution is consistently taken into account. The result agrees with the transverse momentum-dependent factorization formalism. We comment on the possible breakdown of the naive kt-factorization in the dense medium region, due to the unique behaviors for the gluon distributions.
From classical to quantum saturationin the nuclear gluon distribution
NASA Astrophysics Data System (ADS)
Triantafyllopoulos, D. N.
2005-08-01
We study the gluon content of a large nucleus (i) in the semi-classical McLerran-Venugopalan model and (ii) in the high-energy limit as given by the quantum evolution of the color glass condensate. We give a simple and qualitative description of the Cronin effect and high- pT suppression in proton-nucleus collisions.
Prompt atmospheric neutrinos and muons: Dependence on the gluon distribution function
Gelmini, Graciela; Gondolo, Paolo; Varieschi, Gabriele
2000-03-01
We compute the next-to-leading order QCD predictions for the vertical flux of atmospheric muons and neutrinos from decays of charmed particles, for different PDF's (MRS-R1, MRS-R2, CTEQ-4M and MRST) and different extrapolations of these at a small partonic momentum fraction x. We find that the predicted fluxes vary up to almost two orders of magnitude at the largest energies studied, depending on the chosen extrapolation of the PDF's. We show that the spectral index of the atmospheric leptonic fluxes depends linearly on the slope of the gluon distribution function at very small x. This suggests the possibility of obtaining some bounds on this slope in ''neutrino telescopes,'' at values of x not reachable at colliders, provided the spectral index of atmospheric leptonic fluxes could be determined. (c) 2000 The American Physical Society.
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.
How large is the gluon polarization in the statistical parton distributions approach?
NASA Astrophysics Data System (ADS)
Soffer, Jacques; Bourrely, Claude; Buccella, Franco
2015-04-01
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.
Inelastic leptoproduction of J/Ψ and the gluon distribution in the nucleon
NASA Astrophysics Data System (ADS)
Merabet, H.; Mathiot, J.-F.; Mendez-Galain, R.
1994-12-01
In view of the recent experimental results at CERN, we calculate exactly the Q 2-dependence of the inelastic leptoproduction cross-section of J/Ψ. We also make predictions for the high enegy (HERA) as well as low energy (30 GeV electron beam on a fixed target) regimes. The exact calculation of the Q 2-dependence of the cross-section is essential to extract the gluon distribution function from data. We find that using the exact leptoproduction cross-section amounts to increase the power in the parametrization of the gluon distribution function extracted so far in muoproduction experiments
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.
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
Cronin effect and high-p⊥ suppression in the nuclear gluon distribution at small x
NASA Astrophysics Data System (ADS)
Iancu, E.; Itakura, K.; Triantafyllopoulos, D. N.
2004-09-01
We present a systematic, and fully analytic, study of the ratio R between the gluon distribution in a nucleus and that in a proton scaled up by the atomic number A. We consider initial conditions of the McLerran-Venugopalan type, and quantum evolution in the Color Glass Condensate, with both fixed and running coupling. We perform an analytic study of the Cronin effect in the initial conditions and point out an interesting difference between saturating effects and twist effects in the nuclear gluon distribution. We show that the distribution of the gluons which make up the condensate in the initial conditions is localized at low momenta, but this particular feature does not survive after the quantum evolution. We demonstrate that the rapid suppression of the ratio R in the early stages of the evolution is due to the DGLAP-like evolution of the proton, whose gluon distribution grows much faster than that in the nucleus because of the large separation between the respective saturation momenta. The flattening of the Cronin peak, on the other hand, is due to the evolution of the nucleus. We show that the running coupling effects slow down the evolution, but eventually lead to a stronger suppression in R at sufficiently large energies.
Initial energy density and gluon distribution from the glasma in heavy-ion collisions
NASA Astrophysics Data System (ADS)
Fujii, Hirotsugu; Fukushima, Kenji; Hidaka, Yoshimasa
2009-02-01
We estimate the energy density and the gluon distribution associated with the classical fields describing the early-time dynamics of heavy-ion collisions. In the McLerran-Venugopalan model, we first decompose the energy density into the momentum components exactly, with the use of the Wilson line correlators. Then we evolve the energy density with the free-field equation, which is justified by the dominance of the ultraviolet modes near the collision point. We also discuss the improvement that occurs with the inclusion of nonlinear terms into the time evolution. Our numerical results at RHIC energy are fairly consistent with the empirical values.
Initial energy density and gluon distribution from the glasma in heavy-ion collisions
Fujii, Hirotsugu; Fukushima, Kenji; Hidaka, Yoshimasa
2009-02-15
We estimate the energy density and the gluon distribution associated with the classical fields describing the early-time dynamics of heavy-ion collisions. In the McLerran-Venugopalan model, we first decompose the energy density into the momentum components exactly, with the use of the Wilson line correlators. Then we evolve the energy density with the free-field equation, which is justified by the dominance of the ultraviolet modes near the collision point. We also discuss the improvement that occurs with the inclusion of nonlinear terms into the time evolution. Our numerical results at RHIC energy are fairly consistent with the empirical values.
The Higgs transverse momentum distribution in gluon fusion as a multiscale problem
NASA Astrophysics Data System (ADS)
Bagnaschi, E.; Vicini, A.
2016-01-01
We consider Higgs production in gluon fusion and in particular the prediction of the Higgs transverse momentum distribution. We discuss the ambiguities affecting the matching procedure between fixed order matrix elements and the resummation to all orders of the terms enhanced by log( p T H / m H ) factors. Following a recent proposal [1], we argue that the gluon fusion process, computed considering two active quark flavors, is a multiscale problem from the point of view of the resummation of the collinear singular terms. We perform an analysis at parton level of the collinear behavior of the O({α}_s) real emission amplitudes; relying on the collinear singularities structure of the latter, we derive an upper limit to the range of transverse momenta where the collinear approximation is valid. This scale is then used as the value of the resummation scale in the analytic resummation framework or as the value of the h parameter in the POWHEG-BOX code. A variation of this scale can be used to generate an uncertainty band associated to the matching procedure. Finally, we provide a phenomenological analysis in the Standard Model, in the Two Higgs Doublet Model and in the Minimal Supersymmetric Standard Model. In the two latter cases, we provide an ansatz for the central value of the matching parameters not only for a Standard Model-like Higgs boson, but also for heavy scalars and in scenarios where the bottom quark may play the dominant role.
High energy resummation of transverse momentum distributions: Higgs in gluon fusion
NASA Astrophysics Data System (ADS)
Forte, Stefano; Muselli, Claudio
2016-03-01
We derive a general resummation formula for transverse-momentum distributions of hard processes at the leading logarithmic level in the high-energy limit, to all orders in the strong coupling. Our result is based on a suitable generalization of high-energy factorization theorems, whereby all-order resummation is reduced to the determination of the Born-level process but with incoming off-shell gluons. We validate our formula by applying it to Higgs production in gluon fusion in the infinite top mass limit. We check our result up to next-to-leading order by comparison to the high energy limit of the exact expression and to next-to-next-to leading order by comparison to NNLL transverse momentum (Sudakov) resummation, and we predict the high-energy behaviour at next3-to-leading order. We also show that the structure of the result in the small transverse momentum limit agrees to all orders with general constraints from Sudakov resummation.
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.
NASA Astrophysics Data System (ADS)
Boer, Daniël
2016-03-01
A high-energy Electron-Ion Collider (EIC) would offer a most promising tool to study in detail the transverse momentum distributions of gluons inside hadrons. This applies to unpolarized as well as linearly polarized gluons inside unpolarized protons, and to left-right asymmetric distributions of gluons inside transversely polarized protons, the so-called gluon Sivers effect. The inherent process dependence of these distributions can be studied by comparing to similar, but often complementary observables at LHC.
Rapidity distribution of photons from an anisotropic quark-gluon plasma
NASA Astrophysics Data System (ADS)
Bhattacharya, Lusaka; Roy, Pradip
2010-05-01
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, phard(τ), and anisotropy parameter, ξ(τ). 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 (δ=2) interpolating model we observe significant enhancement of photon rapidity distribution at fixed pT, where as for FIC collisionally broadened (δ=2/3) interpolating model the yield increases till y~1. 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.
Scale evolution of gluon TMDPDFs
NASA Astrophysics Data System (ADS)
Echevarria, Miguel G.; Kasemets, Tomas; Mulders, Piet J.; Pisano, Cristian
2015-01-01
By applying the effective field theory machinery we factorize the transverse momentum spectrum of Higgs boson production, where the main hadronic quantities are the gluon transverse momentum dependent parton distribution functions (TMDPDFs). We properly define those quantities, showing explicitly, in the case of an unpolarized hadron, that they are free from rapidity divergences, and extract their evolution properties. It turns out that the evolution for all eight (un-)polarized leading-twist gluon TMDPDFs is driven by the same evolution kernel, for which we derive the necessary ingredients to obtain a resummation of large logarithms at next-tonext-to-leading-logarithmic accuracy. We make predictions for the contribution of linearly polarized gluons to the Higgs boson qT -spectrum.
NASA Astrophysics Data System (ADS)
Dumitru, Adrian; Lappi, Tuomas; Skokov, Vladimir
2015-12-01
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 ˜cos 2 ϕ 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=⟨cos 2 ϕ ⟩˜10 % .
NASA Astrophysics Data System (ADS)
Grinyuk, A. A.; Lipatov, A. V.; Lykasov, G. I.; Zotov, N. P.
2016-01-01
We study the role of the nonperturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the input TMD gluon distribution at a low scale μ02˜1 GeV2 from a fit of inclusive hadron spectra measured at low transverse momenta in p p collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov equation obtained at low x and small gluon transverse momenta outside the saturation region. Then, we extend the input TMD gluon density to higher μ2 numerically using the Catani-Ciafoloni-Fiorani-Marchesini gluon evolution equation. Special attention is paid to phenomenological applications of the obtained TMD gluon density to some LHC processes, which are sensitive to the gluon content of a proton.
Gluon distributions and color charge correlations in a saturated light-cone wavefunction
NASA Astrophysics Data System (ADS)
Mueller, A. H.
2002-11-01
We describe the light-cone wavefunction in the saturation regime in terms of the density of gluons per unit of transverse phase space, the occupation number, and in terms of the color charge correlator. The simple McLerran-Venugopalan model gives what are claimed to be general results for the phase space gluon density, but it does not well describe the general case for the charge correlator. We derive the general momentum dependence and rapidity dependence of the color charge correlator which exhibits strong color shielding. A simple physical picture which leads to these general results is described.
NASA Astrophysics Data System (ADS)
Lansberg, J. P.
2016-02-01
The study of isolated heavy quarkonia, such as J/ψ and Υ, produced in association with a photon in proton-proton collisions at the LHC, is probably the optimal way to get right away a first experimental determination of two gluon transverse-momentum-dependent distribution (TMDs) in an unpolarized proton, f1g and h1⊥g, the latter giving the distribution of linearly polarized gluons. To substantiante this, we calculate the transverse-momentum-dependent effects that arise in the process under study and discuss the feasibility of their measurements.
Ichou, Raphaeelle; D'Enterria, David
2010-07-01
We compare the single inclusive spectra of isolated photons measured at high transverse energy in proton-antiproton collisions at {radical}(s)=1.96 TeV with next-to-leading-order perturbative QCD predictions with various parametrizations of the parton distribution functions (PDFs). Within the experimental and theoretical uncertainties, the Tevatron data can be reproduced equally well by the recent CTEQ6.6, MSTW08, and NNPDF1.2 PDF sets. We also present the predictions for isolated {gamma} spectra in proton-proton collisions at {radical}(s)=14 TeV for central (y=0) and forward (y=4) rapidities relevant for LHC experiments. Different proton PDFs result in maximum variations of order {+-}30% in the expected E{sub T}{sup {gamma}-}differential isolated {gamma} cross sections. The inclusion of the isolated photon data in global PDF fits will place extra independent constraints on the gluon density.
Gluons and the quark sea at high energies: distributions, polarization, tomography
Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.
2011-09-30
This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.
NASA Astrophysics Data System (ADS)
Shahveh, Abolfazl; Taghavi-Shahri, Fatemeh; Arash, Firooz
2010-07-01
In the context of the so-called valon model, we calculate δg/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of δg/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg (Q2), are large.
Unitarity bound for gluon shadowing
Kopeliovich, B. Z.; Levin, E.; Potashnikova, I. K.; Schmidt, Ivan
2009-06-15
Although at small Bjorken x gluons originated from different nucleons in a nucleus overlap in the longitudinal direction, most of them are still well separated in the transverse plane and therefore cannot fuse. For this reason the gluon density in nuclei cannot drop at small x below a certain bottom bound, which we evaluated in a model independent manner assuming the maximal strength of gluon fusion. We also calculated gluon shadowing in the saturated regime using the Balitsky-Kovchegov equation and found the nuclear ratio to be well above the unitarity bound. The recently updated analysis of parton distributions in nuclei, including BNL Relativistic Heavy Ion Collider (RHIC) data on high-p{sub T} hadron production at forward rapidities, led to strong gluon shadowing. Such strong shadowing and therefore the interpretation of the nuclear modification of the p{sub T} spectra in dA collisions at RHIC seem to be inconsistent with this unitarity bound.
NASA Astrophysics Data System (ADS)
Adams, M. R.; Aïd, S.; Anthony, P. L.; Baker, M. D.; Bartlett, J.; Bhatti, A. A.; Braun, H. M.; Busza, W.; Carroll, T. J.; Conrad, J. M.; Coutrakon, G.; Davisson, R.; Derado, I.; Dhawan, S. K.; Dougherty, W.; Dreyer, T.; Dziunikowska, K.; Eckardt, V.; Ecker, U.; Erdmann, M.; Eskreys, A.; Figiel, J.; Gebauer, H. J.; Geesaman, D. F.; Gilman, R.; Green, M. C.; Haas, J.; Halliwell, C.; Hanlon, J.; Hantke, D.; Hughes, V. W.; Jackson, H. E.; Jancso, G.; Jansen, D. M.; Kaufman, S.; Kennedy, R. D.; Kirk, T.; Kobrak, H. G. E.; Krzywdzinski, S.; Kunori, S.; Lord, J. J.; Lubatti, H. J.; McLeod, D.; Magill, S.; Malecki, P.; Manz, A.; Melanson, H.; Michael, D. G.; Mohr, W.; Montgomery, H. E.; Morfin, J. G.; Nickerson, R. B.; O'Day, S.; Olkiewicz, K.; Osborne, L.; Papavassiliou, V.; Pawlik, B.; Pipkin, F. M.; Ramberg, E. J.; Röser, A.; Ryan, J. J.; Salgado, C. W.; Salvarani, A.; Schellman, H.; Schmitt, M.; Schmitz, N.; Schüler, K. P.; Seyerlein, H. J.; Skuja, A.; Snow, G. A.; Söldner-Rembold, S.; Steinberg, P. H.; Stier, H. E.; Stopa, P.; Swanson, R. A.; Talaga, R.; Tentindo-Repond, S.; Trost, H. J.; Venkataramania, H.; Wilhelm, M.; Wilkes, J.; Wilson, Richard; Wittek, W.; Wolbers, S. A.; Zhao, T.
1996-03-01
We have used the energy-energy angular pattern of hadrons in inelastic muon-deuteron scattering to study perturbative QCD effects and to extract the gluon distribution function ηG( η) of the nucleon, where η is the fractional momentum carried by the gluon. The data were taken with the E665 spectrometer using the Fermilab Tevatron muon beam with a mean beam energy of 490 GeV. We present ηG( η) for 0.005< η<0.05 and at an average Q 2 of 8 GeV2 using this new technique. We find that ηG( η) in this region can be described by ηG( η) α ηλ with λ=-0.87±0.09( stat.)±{0.37/0.32}( sys.). We compare our results to expectations from various parametrizations of the parton distribution function and also to results from HERA.
Demartin, Federico; Mariani, Elisa; Forte, Stefano; Vicini, Alessandro; Rojo, Juan
2010-07-01
We present a systematic study of uncertainties due to parton distributions (PDFs) and the strong coupling on the gluon-fusion production cross section of the standard model Higgs at the Tevatron and LHC colliders. We compare procedures and results when three recent sets of PDFs are used, CTEQ6.6, MSTW08, and NNPDF1.2, and we discuss specifically the way PDF and strong coupling uncertainties are combined. We find that results obtained from different PDF sets are in reasonable agreement if a common value of the strong coupling is adopted. We show that the addition in quadrature of PDF and {alpha}{sub s} uncertainties provides an adequate approximation to the full result with exact error propagation. We discuss a simple recipe to determine a conservative PDF+{alpha}{sub s} uncertainty from available global parton sets, and we use it to estimate this uncertainty on the given process to be about 10% at the Tevatron and 5% at the LHC for a light Higgs.
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.
Quark-Gluon Plasma Model and Origin of Magic Numbers
Ghahramany, N.; Ghanaatian, M.; Hooshmand, M.
2008-04-21
Using Boltzman distribution in a quark-gluon plasma sample it is possible to obtain all existing magic numbers and their extensions without applying the spin and spin-orbit couplings. In this model it is assumed that in a quark-gluon thermodynamic plasma, quarks have no interactions and they are trying to form nucleons. Considering a lattice for a central quark and the surrounding quarks, using a statistical approach to find the maximum number of microstates, the origin of magic numbers is explained and a new magic number is obtained.
Gluon mass generation without seagull divergences
Aguilar, Arlene C.; Papavassiliou, Joannis
2010-02-01
Dynamical gluon mass generation has been traditionally plagued with seagull divergences, and all regularization procedures proposed over the years yield finite but scheme-dependent gluon masses. In this work we show how such divergences can be eliminated completely by virtue of a characteristic identity, valid in dimensional regularization. The ability to trigger the aforementioned identity hinges crucially on the particular Ansatz employed for the three-gluon vertex entering into the Schwinger-Dyson equation governing the gluon propagator. The use of the appropriate three-gluon vertex brings about an additional advantage: one obtains two separate (but coupled) integral equations, one for the effective charge and one for the gluon mass. This system of integral equations has a unique solution, which unambiguously determines these two quantities. Most notably, the effective charge freezes in the infrared, and the gluon mass displays power-law running in the ultraviolet, in agreement with earlier considerations.
NASA Astrophysics Data System (ADS)
Anikin, I. V.; Teryaev, O. V.
2015-12-01
In this letter, we revise the QED gauge invariance for the hadron tensor of Drell-Yan type processes with the transversely polarized hadron. We perform our analysis within the Feynman gauge for gluons and make a comparison with the results obtained within the light-cone gauge. We demonstrate that QED gauge invariance leads, first, to the need of a non-standard diagram and, second, to the absence of gluon poles in the correlators < ψ bar γ⊥A+ ψ > related traditionally to dT (x , x) / dx. As a result, these terms disappear from the final QED gauge invariant hadron tensor. We also verify the absence of such poles by analyzing the corresponding light-cone Dirac algebra.
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
Jet calculus beyond leading order for the gluon sector
Gunion, J.F.; Kalinowski, J.
1984-04-01
We report results for the order-C/sub A/ /sup 2/..cap alpha../sub s/ /sup 2/ jet calculus three-, two-, and one-gluon distributions of the pure gluon singlet channel. Included is an independent calculation of the C/sub A/ /sup 2/ part of the gluon..-->..gluon inclusive distribution which has been a subject of controversy for several years. We confirm the results of Furmanski and Petronzio for scheme-independent observables.
Asymptocic Freedom of Gluons in Hamiltonian Dynamics
NASA Astrophysics Data System (ADS)
Gómez-Rocha, María; Głazek, Stanisław D.
2016-07-01
We derive asymptotic freedom of gluons in terms of the renormalized SU(3) Yang-Mills Hamiltonian in the Fock space. Namely, we use the renormalization group procedure for effective particles to calculate the three-gluon interaction term in the front-form Yang-Mills Hamiltonian using a perturbative expansion in powers of g up to third order. The resulting three-gluon vertex is a function of the scale parameter s that has an interpretation of the size of effective gluons. The corresponding Hamiltonian running coupling constant exhibits asymptotic freedom, and the corresponding Hamiltonian {β} -function coincides with the one obtained in an earlier calculation using a different generator.
Subtleties in obtaining the electrostatic energy of continuous distributions
NASA Astrophysics Data System (ADS)
Bezerra, M.; Souza, Reinaldo de Melo e.; Kort-Kamp, W. J. M.; Farina, C.
2014-11-01
The mathematical steps that generalize the expression for the electrostatic energy of a set of point charges to the corresponding expression for a continuous charge distribution involve a few subtleties that are not usually discussed in standard introductory or advanced electromagnetic textbooks. In this paper, we point out such subtleties and discuss how to deal with them in cases of volume and surface charge distributions. We also show explicitly that it is not possible to define electrostatic energy for a linear charge distribution, since this energy would be divergent. Finally, we use dimensional analysis to recover our results in a simpler and more elegant form.
Significance of gluon density at soft and hard processes at LHC
NASA Astrophysics Data System (ADS)
Grinyuk, A. A.; Lipatov, A. V.; Lykasov, G. I.
2015-11-01
We study the role of the non-perturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the TMD gluon distribution from the fit of the inclusive hadron spectra measured at low transverse momenta in pp collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation obtained at small transverse momenta outside the saturation region. A special attention is put to the phenomenological applications of presented TMD parton densities to some LHC processes, which are sensitive to the quark and gluon content of a proton.
Shining a gluon beam through quark-gluon plasma
NASA Astrophysics Data System (ADS)
Chesler, Paul M.; Ho, Ying-Yu; Rajagopal, Krishna
2012-06-01
We compute the energy density radiated by a quark undergoing circular motion in strongly coupled N=4 supersymmetric Yang-Mills plasma. If it were in vacuum, this quark would radiate a beam of strongly coupled radiation whose angular distribution has been characterized and is very similar to that of synchrotron radiation produced by an electron in circular motion in electrodynamics. Here, we watch this beam of gluons getting quenched by the strongly coupled plasma. We find that a beam of gluons of momenta ˜q≫πT is attenuated rapidly, over a distance ˜q1/3(πT)-4/3 in a plasma with temperature T. As the beam propagates through the plasma at the speed of light, it sheds trailing sound waves with momenta ≲πT. Presumably these sound waves would thermalize in the plasma if they were not hit soon after their production by the next pulse of gluons from the lighthouselike rotating quark. At larger and larger q, the trailing sound wave becomes less and less prominent. The outward-going beam of gluon radiation itself shows no tendency to spread in angle or to shift toward larger wavelengths, even as it is completely attenuated. In this regard, the behavior of the beam of gluons which we analyze is reminiscent of the behavior of jets produced in heavy ion collisions at the LHC which lose a significant fraction of their energy without appreciable change in their angular distribution or their momentum distribution as they plow through the strongly coupled quark-gluon plasma produced in these collisions.
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.
Obtaining an unbiased redshift distribution for submm galaxies
NASA Astrophysics Data System (ADS)
Ivison, Rob; Norris, Ray; Feain, Ilana; Huynh, Minh; Smail, Ian; Thomson, Alasdair
2009-07-01
We request 36hr with ATCA to test a new method for determining an unbiased redshift distribution for submm galaxies (SMGs) - a critical parameter capable of breaking degeneracies in galaxy evolution models. Our method is based on the expectation that dusty ULIRGs will exhibit maser activity similar to that observed in other IR-luminous AGN. As well as determining redshifts, detections will allow us to estimate the mass of the central black hole (to compare with X-ray-based estimates), to pinpoint the maser relative to the synchrotron emission, and to explore any correlation between L(FIR) and L(H2O). The key to our project is the largest deep submm survey undertaken thus far - LESS - in the Extended Chandra Deep Field South. We propose to piggyback on the Huynh et al. 5-GHz survey of ECDFS, going 2.3x deeper in two pointings centred on over-densities of bright SMGs.
Sugano, K.
1986-09-01
The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed.
On relevance of triple-gluon fusion in hadroproduction
NASA Astrophysics Data System (ADS)
Motyka, Leszek; Sadzikowski, Mariusz
2015-05-01
A contribution to hadroproduction is analyzed in which the meson production is mediated by three-gluon partonic state, with two gluons coming from the target and one gluon from the projectile. This mechanism involves double gluon density in one of the protons, hence this contribution enters at a non-leading twist. It is, however, relevant due to an enhancement factor coming from large double gluon density at small . We calculate the three-gluon contribution to hadroproduction within perturbative QCD in the -factorization framework. Results are obtained for differential -dependent cross sections for all polarizations and for the sum over the polarization components. 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 . We suggest production in proton-nucleus collision as a possible probe of the triple-gluon mechanism.
Fully gauge-invariant maximally path-dependent gluon TMD: Coordinate representation
NASA Astrophysics Data System (ADS)
Cherednikov, Igor O.
2016-02-01
We propose an approach to obtain gauge-invariant maximally path-dependent operator definition of the gluon transverse-momentum dependent distribution function (gTMD). We demonstrate that the evolution equations for the gTMD can be derived from the shape- variation integral-differential equations formulated in the coordinate space.
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 saturation in a saturated environment
NASA Astrophysics Data System (ADS)
Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan
2011-07-01
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 QsA2, in AA compared with pA collisions.
Gluon TMDs in Quarkonium Production
NASA Astrophysics Data System (ADS)
Signori, Andrea
2016-04-01
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.
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.
Nonperturbative gluon and ghost propagators in d = 3
Papavassiliou, Joannis
2011-05-23
We study the nonperturbative gluon and ghost propagators in d = 3 Yang-Mills, using the Schwinger-Dyson equations of the pinch technique. The use of the Schwinger mechanism leads to the dynamical generation of a gluon mass, which, in turn, gives rise to an infrared finite gluon propagator and ghost dressing function. The propagators obtained are in very good agreement with the results of SU(2) lattice simulations.
Role of monopoles in a gluon plasma
Ratti, Claudia; Shuryak, Edward
2009-08-01
We study the role of magnetic monopoles at high enough temperature T>2T{sub c}, when they can be considered heavy, rare objects embedded into matter consisting mostly of the usual 'electric' quasiparticles, quarks, and gluons. We review available lattice results on monopoles at finite temperatures. Then we proceed to classical and quantum charge-monopole scattering, solving the problem of gluon-monopole scattering for the first time. The explicit calculations are performed in the framework of the Georgi-Glashow model; the results that we obtain are nevertheless quite general. Connections to QCD are carefully discussed. We find that, while the gluon-monopole scattering hardly influences thermodynamic quantities, it does produce a large transport cross section, significantly exceeding that for pQCD gluon-gluon scattering up to quite high T. Thus, in spite of their relatively small density at high T, monopoles are extremely important for quark-gluon plasma transport properties, keeping viscosity small enough for hydrodynamics to work at the LHC.
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.
EXPLORING THE POLARIZATION OF GLUONS IN THE NUCLEON.
STRATMANN,M.; VOGELSANG,W.
2007-10-22
We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.
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
Dark matter searches employing asymmetric velocity distributions obtained via the Eddington approach
NASA Astrophysics Data System (ADS)
Vergados, J. D.; Moustakidis, Ch. C.; Owen, D.
2016-08-01
Starting from WIMP density profiles, in the framework of the Eddington approach, we obtain the energy distribution f(E) of dark matter in our vicinity. Assuming a factorizable phase space function, f(E , L) = F(E) FL(L) , we obtain the velocity dispersions and the anisotropy parameter β in terms of the parameters describing the angular momentum dependence. By employing the derived expression f(E) we construct axially symmetric WIMP velocity distributions. The obtained distributions automatically have a velocity upper bound, as a consequence of the fact that they are associated with a gravitationally bound system, and are characterized by an anisotropy parameter β. We then show how such velocity distributions can be used in determining the event rates, including modulation, both in the standard as well directional WIMP searches.
Thermalization of gluons with Bose-Einstein condensation.
Xu, Zhe; Zhou, Kai; Zhuang, Pengfei; Greiner, Carsten
2015-05-01
We study the thermalization of gluons far from thermal equilibrium in relativistic kinetic theory. The initial distribution of gluons is assumed to resemble that in the early stage of ultrarelativistic heavy ion collisions. Only elastic scatterings in static, nonexpanding gluonic matter are considered. At first we show that the occurrence of condensation in the limit of vanishing particle mass requires a general constraint for the scattering matrix element. Then the thermalization of gluons with Bose-Einstein condensation is demonstrated in a transport calculation. We see a continuously increasing overpopulation of low energy gluons, followed by a decrease to the equilibrium distribution, when the condensation occurs. The times of the completion of the gluon condensation and of the entropy production are calculated. These times scale inversely with the energy density. PMID:26000996
Multiplicity and transverse energy of produced gluon in relativistic heavy ion collision
Xiao Bowen
2005-09-01
We present a simple gluon production picture that is based on the McLerran-Venugopalan model and gluon BFKL evolution in relativistic heavy-ion collision. Results for the multiplicity and transverse energy distribution in both the central and forward rapidity regions for gluon production in early stages of heavy-ion collisions at the LHC are given. Finally, we provide a general qualitative discussion of the consequences of the forward rapidity behavior of produced gluons.
Constituent gluons and the static quark potential
NASA Astrophysics Data System (ADS)
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 truncated-basis treatment of hadronic states which include constituent gluons. As an illustration, we apply this hybrid approach to the heavy quark potential, for quark-antiquark separations up to 2.4 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of 4 times greater than the asymptotic string tension. In our approach we show that a single constituent gluon is in principle sufficient, up to 2.4 fm, to reduce this overshoot by the factor required. The static potential remains linear, although the precise value of the string tension depends on details of the Couloumb gauge ghost and gluon propagators in the infrared regime. In this connection we present new lattice results for the transverse gluon propagator in position space.
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.
Pore size distribution in porous glass: fractal dimension obtained by calorimetry
NASA Astrophysics Data System (ADS)
Neffati, R.; Rault, J.
2001-05-01
By differential Scanning Calorimetry (DSC), at low heating rate and using a technique of fractionation, we have measured the equilibrium DSC signal (heat flow) J q 0 of two families of porous glass saturated with water. The shape of the DSC peak obtained by these techniques is dependent on the sizes distribution of the pores. For porous glass with large pore size distribution, obtained by sol-gel technology, we show that in the domain of ice melting, the heat flow Jq is related to the melting temperature depression of the solvent, Δ T m , by the scaling law: J q 0˜Δ T m - (1 + D). We suggest that the exponent D is of the order of the fractal dimension of the backbone of the pore network and we discuss the influence of the variation of the melting enthalpy with the temperature on the value of this exponent. Similar D values were obtained from small angle neutron scattering and electronic energy transfer measurements on similar porous glass. The proposed scaling law is explained if one assumes that the pore size distribution is self similar. In porous glass obtained from mesomorphic copolymers, the pore size distribution is very sharp and therefore this law is not observed. One concludes that DSC, at low heating rate ( q? 2°C/min) is the most rapid and less expensive method for determining the pore distribution and the fractal exponent of a porous material.
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...
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 $x \\sim 1$.
Gluon TMD in particle production from low to moderate x
Balitsky, I.; Tarasov, A.
2016-06-28
Here, 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 smallmore » $$x \\ll 1$$ to linear evolution at moderate $$x \\sim 1$$.« less
Gluon TMD in particle production from low to moderate x
NASA Astrophysics Data System (ADS)
Balitsky, I.; Tarasov, A.
2016-06-01
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.
NASA Astrophysics Data System (ADS)
Ma, Chao; An, Wei; Deng, Xinpu
2015-10-01
The Ground Control Points (GCPs) is an important source of fundamental data in geometric correction for remote sensing imagery. The quantity, accuracy and distribution of GCPs are three factors which may affect the accuracy of geometric correction. It is generally required that the distribution of GCP should be uniform, so they can fully control the accuracy of mapping regions. In this paper, we establish an objective standard of evaluating the uniformity of the GCPs' distribution based on regional statistical information (RSI), and get an optimal distribution of GCPs. This sampling method is called RSIS for short in this work. The Amounts of GCPs in different regions by equally partitioning the image in regions in different manners are counted which forms a vector called RSI vector in this work. The uniformity of GCPs' distribution can be evaluated by a mathematical quantity of the RSI vector. An optimal distribution of GCPs is obtained by searching the RSI vector with the minimum mathematical quantity. In this paper, the simulation annealing is employed to search the optimal distribution of GCPs that have the minimum mathematical quantity of the RSI vector. Experiments are carried out to test the method proposed in this paper, and sampling designs compared are simple random sampling and universal kriging model-based sampling. The experiments indicate that this method is highly recommended as new GCPs sampling design method for geometric correction of remotely sensed imagery.
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.
NASA Astrophysics Data System (ADS)
Kang, Hyun-Ju; Choi, Hyeok; Kim, Jae-Hyun; Lee, Se-Hun; Yoo, Tae-Ho; Chung, Chin-Wook
2016-06-01
A modified central difference method (MCDM) is proposed to obtain the electron energy distribution functions (EEDFs) in single Langmuir probes. Numerical calculation of the EEDF with MCDM is simple and has less noise. This method provides the second derivatives at a given point as the weighted average of second order central difference derivatives calculated at different voltage intervals, weighting each by the square of the interval. In this paper, the EEDFs obtained from MCDM are compared to those calculated via the averaged central difference method. It is found that MCDM effectively suppresses the noises in the EEDF, while the same number of points are used to calculate of the second derivative.
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.
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. PMID:12382811
NASA Astrophysics Data System (ADS)
Peshier*, André; Giovannoni, Dino
2016-01-01
We put forward the idea that the quark-gluon plasma might exist way below the usual confinement temperature Tc. Our argument rests on the possibility that the plasma produced in heavy-ion collisions could reach a transient quasi-equilibrium with ‘over-occupied’ gluon density, as advocated by Blaizot et al. Taking further into account that gluons acquire an effective mass by interaction effects, they can have a positive chemical potential and therefore behave similarly to non-relativistic bosons. Relevant properties of this dense state of interacting gluons, which we dub serried glue, can then be inferred on rather general grounds from Maxwell's relation.
Evidence for polarization of gluons in the proton.
de Florian, Daniel; Sassot, Rodolfo; Stratmann, Marco; Vogelsang, Werner
2014-07-01
We discuss the impact of recent high-statistics Relativistic Heavy Ion Collider data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find evidence for a nonvanishing polarization of gluons in the region of momentum fraction and at the scales mostly probed by the data. Although information from low momentum fractions is presently lacking, this finding is suggestive of a significant contribution of gluon spin to the proton spin, thereby limiting the amount of orbital angular momentum required to balance the proton spin budget. PMID:25032920
Diphoton excess at 750 GeV: gluon-gluon fusion or quark-antiquark annihilation?
NASA Astrophysics Data System (ADS)
Gao, Jun; Zhang, Hao; Zhu, Hua Xing
2016-06-01
Recently, ATLAS and CMS collaborations reported an excess in the measurement of diphoton events, which can be explained by a new resonance with a mass around 750 GeV. In this work, we explored the possibility of identifying if the hypothetical new resonance is produced through gluon-gluon fusion or quark-antiquark annihilation, or tagging the beam. Three different observables for beam tagging, namely the rapidity and transverse-momentum distribution of the diphoton, and one tagged bottom-jet cross section, are proposed. Combining the information gained from these observables, a clear distinction of the production mechanism for the diphoton resonance is promising.
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.
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}.
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.
Baverel, Paul G; Savic, Radojka M; Karlsson, Mats O
2011-02-01
When parameter estimates are used in predictions or decisions, it is important to consider the magnitude of imprecision associated with the estimation. Such imprecision estimates are, however, presently lacking for nonparametric algorithms intended for nonlinear mixed effects models. The objective of this study was to develop resampling-based methods for estimating imprecision in nonparametric distribution (NPD) estimates obtained in NONMEM. A one-compartment PK model was used to simulate datasets for which the random effect of clearance conformed to a (i) normal (ii) bimodal and (iii) heavy-tailed underlying distributional shapes. Re-estimation was conducted assuming normality under FOCE, and NPDs were estimated sequential to this step. Imprecision in the NPD was then estimated by means of two different resampling procedures. The first (full) method relies on bootstrap sampling from the raw data and a re-estimation of both the preceding parametric (FOCE) and the nonparametric step. The second (simplified) method relies on bootstrap sampling of individual nonparametric probability distributions. Nonparametric 95% confidence intervals (95% CIs) were obtained and mean errors (MEs) of the 95% CI width were computed. Standard errors (SEs) of nonparametric population estimates were obtained using the simplified method and evaluated through 100 stochastic simulations followed by estimations (SSEs). Both methods were successfully implemented to provide imprecision estimates for NPDs. The imprecision estimates adequately reflected the reference imprecision in all distributional cases and regardless of the numbers of individuals in the original data. Relative MEs of the 95% CI width of CL marginal density when original data contained 200 individuals were equal to: (i) -22 and -12%, (ii) -22 and -9%, (iii) -13 and -5% for the full and simplified (n = 100), respectively. SEs derived from the simplified method were consistent with the ones obtained from 100 SSEs. In conclusion
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.
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.
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.
NASA Astrophysics Data System (ADS)
Jonsson, Jacob C.; Brandén, Henrik
2007-09-01
This paper demonstrates a method to determine the bidirectional transmittance distribution function (BTDF) using an integrating sphere. Information about the sample's angle-dependent scattering is obtained by making transmittance measurements with the sample at different distances from the integrating sphere. Knowledge about the illuminated area of the sample and the geometry of the sphere port in combination with the measured data combines to a system of equations that includes the angle-dependent transmittance. The resulting system of equations is an ill-posed problem which rarely gives a physical solution. A solvable system is obtained by using Tikhonov regularization on the ill-posed problem. The solution to this system can then be used to obtain the BTDF. Four bulk-scattering samples were characterised using two goniophotometers and the described method to verify the validity of the new method. The agreement shown is excellent for the more diffuse samples. The solution to the low-scattering samples contains unphysical oscillations, but still gives the correct shape of the solution. The origin of the oscillations and why they are more prominent in low-scattering samples are discussed.
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.
Quark and Gluon Tagging at the LHC
NASA Astrophysics Data System (ADS)
Gallicchio, Jason; Schwartz, Matthew D.
2011-10-01
Being able to distinguish light-quark jets from gluon jets on an event-by-event basis could significantly enhance the reach for many new physics searches at the Large Hadron Collider. Through an exhaustive search of existing and novel jet substructure observables, we find that a multivariate approach can filter out over 95% of the gluon jets while keeping more than half of the light-quark jets. Moreover, a combination of two simple variables, the charge track multiplicity and the pT-weighted linear radial moment (girth), can achieve similar results. Our study is only Monte Carlo based, so other observables constructed using different jet sizes and parameters are used to highlight areas that deserve further theoretical and experimental scrutiny. Additional information, including distributions of around 10 000 variables, can be found at http://jets.physics.harvard.edu/qvg/.
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.
A study of coherence of soft gluons in hadron jets
NASA Astrophysics Data System (ADS)
Akrawy, M. Z.; Alexander, G.; Allison, J.; Allport, P. P.; Anderson, K. J.; Armitage, J. C.; Arnison, G. T. J.; Ashton, P.; Azuelos, G.; Baines, J. T. M.; Ball, A. H.; Banks, J.; Barker, G. J.; Barlow, R. J.; Batley, J. R.; Becker, J.; Behnke, T.; Bell, K. W.; Bella, G.; Bethke, S.; Biebel, O.; Binder, U.; Bloodworth, I. J.; Bock, P.; Breuker, H.; Brown, R. M.; Brun, R.; Buijs, A.; Burckhart, H. J.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlton, D. G.; Chrin, J. T. M.; Clarke, P. E. L.; Cohen, I.; Collins, W. J.; Conboy, J. E.; Couch, M.; Coupland, M.; Cuffiani, M.; Dado, S.; Dallavalle, G. M.; Debu, P.; Deninno, M. M.; Dieckmann, A.; Dittmar, M.; Dixit, M. S.; Duchovni, E.; Duerdoth, I. P.; Dumas, D. J. P.; El Mamouni, H.; Elcombe, P. A.; Estabrooks, P. G.; Etzion, E.; Fabbri, F.; Farthouat, P.; Fischer, H. M.; Fong, D. G.; French, M. T.; Fukunaga, C.; Gaidot, A.; Ganel, O.; Gary, J. W.; Gascon, J.; Geddes, N. I.; Gee, C. N. P.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Giacomelli, G.; Gibson, V.; Gibson, W. R.; Gillies, J. D.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Granite, D.; Gross, E.; Grunhaus, J.; Hagedorn, H.; Hagemann, J.; Hansroul, M.; Hargrove, C. K.; Harrus, I.; Hart, J.; Hattersley, P. M.; Hauschild, M.; Hawkes, C. M.; Heflin, E.; Hemingway, R. J.; Heuer, R. D.; Hill, J. C.; Hillier, S. J.; Ho, C.; Hobbs, J. D.; Hobson, P. R.; Hochman, D.; Holl, B.; Homer, R. J.; Hou, S. R.; Howarth, C. P.; Hughes-Jones, R. E.; Humbert, R.; Igo-Kemenes, P.; Ihssen, H.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Jobes, M.; Jones, R. W. L.; Jovanovic, P.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Kellogg, R. G.; Kennedy, B. W.; Kleinwort, C.; Klem, D. E.; Knop, G.; Kobayashi, T.; Kokott, T. P.; Köpke, L.; Kowalewski, R.; Kreutzmann, H.; Kroll, J.; Kuwano, M.; Kyberd, P.; Lafferty, G. D.; Lamarche, F.; Larson, W. J.; Layter, J. G.; Le Du, P.; Leblanc, P.; Lee, A. M.; Lehto, M. H.; Lellouch, D.; Lennert, P.; Lessard, L.; Levinson, L.; Lloyd, S. L.; Loebinger, F. K.; Lorah, J. M.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Ma, J.; Macbeth, A. A.; Mannelli, M.; Marcellini, S.; Maringer, G.; Martin, A. J.; Martin, J. P.; Mashimo, T.; Mättig, P.; Maur, U.; McMahon, T. J.; McNutt, J. R.; McPherson, A. C.; Meijers, F.; Menszner, D.; Merritt, F. S.; Mes, H.; Michelini, A.; Middleton, R. P.; Mikenberg, G.; Miller, D. J.; Milstene, C.; Minowa, M.; Mohr, W.; Montanari, A.; Mori, T.; Moss, M. W.; Murphy, P. G.; Murray, W. J.; Nellen, B.; Nguyen, H. H.; Nozaki, M.; O'Dowd, A. J. P.; O'Neale, S. W.; O'Neill, B. P.; Oakham, F. G.; Odorici, F.; Ogg, M.; Oh, H.; Oreglia, M. J.; Orito, S.; Pansart, J. P.; Patrick, G. N.; Pawley, S. J.; Pfister, P.; Pilcher, J. E.; Pinfold, J. L.; Plane, D. E.; Poli, B.; Pouladdej, A.; Pritchard, T. W.; Quast, G.; Raab, J.; Redmond, M. W.; Rees, D. L.; Regimbald, M.; Riles, K.; Roach, C. M.; Robins, S. A.; Rollnik, A.; Roney, J. M.; Rossberg, S.; Rossi, A. M.; Routenburg, P.; Runge, K.; Runolfsson, O.; Sanghera, S.; Sansum, R. A.; Sasaki, M.; Saunders, B. J.; Schaile, A. D.; Schaile, O.; Schappert, W.; Scharff-Hansen, P.; Schreiber, S.; Schwarz, J.; Shapira, A.; Shen, B. C.; Sherwood, P.; Simon, A.; Singh, P.; Siroli, G. P.; Skuia, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Springer, R. W.; Sproston, M.; Stephens, K.; Stier, H. E.; Ströhmer, R.; Strom, D.; Takeda, H.; Takeshita, T.; Tsukamoto, T.; Turner, M. F.; Tysarczyk-Niemeyer, G.; Van den plas, D.; VanDalen, G. J.; Vasseur, G.; Virtue, C. J.; von der Schmitt, H.; von Krogh, J.; Wagner, A.; Wahl, C.; Ward, C. P.; Ward, D. R.; Waterhouse, J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, M.; Weisz, S.; Wells, P. S.; Wermes, N.; Weymann, M.; Wilson, G. W.; Wilson, J. A.; Wingerter, I.; Winterer, V.-H.; Wood, N. C.; Wotton, S.; Wuensch, B.; Wyatt, T. R.; Yaari, R.; Yang, Y.; Yekutieli, G.; Yoshida, T.; Zeuner, W.; Zorn, G. T.; OPAL Collaboration
1990-09-01
We study the inclusive momentum distribution of charged particles in multihadronic events produced in e +e - annihilations at ECM∼ M(Z 0). We find agreement with the analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from CM energies between 14 and 91 GeV, we study the dependence of the inclusive momentum distribution on the centre of momentum energy. We find that the analytical formulae describe the data over the entire energy range. Both the momentum distribution at a fixed energy and the change with energy are described by QCD shower Monte Carlo's which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and momentum spectra.
Jonsson, Jacob C.; Branden, Henrik
2006-10-19
This paper demonstrates a method to determine thebidirectional transfer distribution function (BTDF) using an integratingsphere. Information about the sample's angle dependent scattering isobtained by making transmittance measurements with the sample atdifferent distances from the integrating sphere. Knowledge about theilluminated area of the sample and the geometry of the sphere port incombination with the measured data combines to an system of equationsthat includes the angle dependent transmittance. The resulting system ofequations is an ill-posed problem which rarely gives a physical solution.A solvable system is obtained by using Tikhonov regularization on theill-posed problem. The solution to this system can then be used to obtainthe BTDF. Four bulk-scattering samples were characterised using both twogoniophotometers and the described method to verify the validity of thenew method. The agreement shown is great for the more diffuse samples.The solution to the low-scattering samples contains unphysicaloscillations, butstill gives the correct shape of the solution. Theorigin of the oscillations and why they are more prominent inlow-scattering samples are discussed.
Exact kinematics in the small-x evolution of the color dipole and gluon cascade
Motyka, Leszek; Stasto, Anna M.
2009-04-15
The problem of kinematic effects in gluon and color dipole cascades is addressed in the large N{sub c} limit of SU(N{sub c}) Yang-Mills theory. We investigate the tree-level multigluon components of the gluon light-cone wave functions in the light-cone gauge keeping the exact kinematics of the gluon emissions. We focus on the components with all helicities identical to the helicity of the incoming gluon. The recurrence relations for the gluon wave functions are derived. In the case when the virtuality of the incoming gluon is neglected the exact form of the multigluon wave function is obtained. Furthermore, we propose an approximate scheme to treat the kinematic effects in the color dipole evolution kernel. The new kernel entangles longitudinal and transverse degrees of freedom and leads to a reduced diffusion in the impact parameter. When evaluated in the next-to-leading logarithmic (NLL) accuracy, the kernel reproduces the correct form of the double logarithmic terms of the dipole size ratios present in the exact NLL dipole kernel. Finally, we analyze the scattering of the incoming gluon light-cone components off a gluon target and the fragmentation of the scattered state into the final state. The equivalence of the resulting amplitudes and the maximally helicity-violating amplitudes is demonstrated in the special case when the target gluon is far in rapidity from the evolved gluon wave function.
T-Odd Gluon TMDs Inside a Transversely Polarized Hadron
NASA Astrophysics Data System (ADS)
Echevarria, Miguel G.
2016-03-01
We consider the relevant gluon transverse momentum dependent distributions (TMDs) in the spin asymmetries generated by the scattering off transversely polarized hadrons. At large transverse momentum they can be expressed in terms of different collinear distributions, via perturbatively calculable Wilson coefficients. We calculate these coefficients at next-to-leading order, and show that when the small-x limit is taken only one independent function remains for dipole-type gluon TMDs: the so-called spin-dependent odderon. This universal origin for the spin asymmetries is of importance to better understand hadron substructure.
A simple approximate method for obtaining spanwise lift distributions over swept wings
NASA Technical Reports Server (NTRS)
Diederich, Franklin W
1948-01-01
It is shown how Schrenk's empirical method of estimating the lift distribution over straight wings can be adapted to swept wings by replacing the elliptical distribution by a new "ideal" distribution which varies with sweep.The application of the method is discussed in detail and several comparisons are made to show the agreement of the proposed method with more rigorous ones. It is shown how first-order compressibility corrections applicable to subcritical speeds may be included in this method.
One gluon, two gluon: multigluon production via high energy evolution
NASA Astrophysics Data System (ADS)
Kovner, Alex; Lublinsky, Michael
2006-11-01
We develop an approach for calculating the inclusive multigluon production within the JIMWLK high energy evolution. We give a formal expression of multigluon cross section in terms of a generating functional for arbitrary number of gluons n. In the dipole limit the expression simplifies dramatically. We recover the previously known results for single and double gluon inclusive cross section and generalize those for arbitrary multigluon amplitude in terms of Feynman diagramms of Pomeron - like objects coupled to external rapidity dependent field s(η). We confirm the conclusion that the AGK cutting rules in general are violated in multigluon production. However we present an argument to the effect that for doubly inclusive cross section the AGK diagramms give the leading contribution at high energy, while genuine violation only occurs for triple and higher inclusive gluon production. We discuss some general properties of our expressions and suggest a line of argument to simplify the approach further.
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...
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.
Technology Transfer Automated Retrieval System (TEKTRAN)
The fiber testing instruments such as HVI can rapidly measure fiber length by testing a tapered fiber beard of the sample. But these instruments that use the beard testing method only report a limited number of fiber length parameters instead of the complete length distribution that is important fo...
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.
Analysis of the spatial distribution of prostate cancer obtained from histopathological images
NASA Astrophysics Data System (ADS)
Diaz, Kristians; Castaneda, Benjamin; Montero, Maria Luisa; Yao, Jorge; Joseph, Jean; Rubens, Deborah; Parker, Kevin J.
2013-03-01
Understanding the spatial distribution of prostate cancer and how it changes according to prostate specific antigen (PSA) values, Gleason score, and other clinical parameters may help comprehend the disease and increase the overall success rate of biopsies. This work aims to build 3D spatial distributions of prostate cancer and examine the extent and location of cancer as a function of independent clinical parameters. The border of the gland and cancerous regions from wholemount histopathological images are used to reconstruct 3D models showing the localization of tumor. This process utilizes color segmentation and interpolation based on mathematical morphological distance. 58 glands are deformed into one prostate atlas using a combination of rigid, affine, and b-spline deformable registration techniques. Spatial distribution is developed by counting the number of occurrences in a given position in 3D space from each registered prostate cancer. Finally a difference between proportions is used to compare different spatial distributions. Results show that prostate cancer has a significant difference (SD) in the right zone of the prostate between populations with PSA greater and less than 5ng/ml. Age does not have any impact in the spatial distribution of the disease. Positive and negative capsule-penetrated cases show a SD in the right posterior zone. There is SD in almost all the glands between cases with tumors larger and smaller than 10% of the whole prostate. A larger database is needed to improve the statistical validity of the test. Finally, information from whole-mount histopathological images may provide better insight into prostate cancer.
Quark and Gluon Orbital Angular Momentum: Where Are We?
NASA Astrophysics Data System (ADS)
Lorcé, Cédric; Liu, Keh-Fei
2016-06-01
The orbital angular momentum of quarks and gluons contributes significantly to the proton spin budget and attracted a lot of attention in the recent years, both theoretically and experimentally. We summarize the various definitions of parton orbital angular momentum together with their relations with parton distributions functions. In particular, we highlight current theoretical puzzles and give some prospects.
Antiangular Ordering of Gluon Radiation in QCD Media
Mehtar-Tani, Yacine; Salgado, Carlos A.; Tywoniuk, Konrad
2011-03-25
We investigate angular and energy distributions of medium-induced gluon emission off a quark-antiquark antenna in the framework of perturbative QCD as an attempt toward understanding, from first principles, jet evolution inside the quark-gluon plasma. In-medium color coherence between emitters, neglected in all previous calculations, leads to a novel mechanism of soft-gluon radiation. The structure of the corresponding spectrum, in contrast with known medium-induced radiation, i.e., off a single emitter, retains some properties of the vacuum case; in particular, it exhibits a soft divergence. However, as opposed to the vacuum, the collinear singularity is regulated by the pair opening angle, leading to a strict angular separation between vacuum and medium-induced radiation, denoted as antiangular ordering. We comment on the possible consequences of this new contribution for jet observables in heavy-ion collisions.
Gluon polarization in the proton
Bass, Steven D.; Casey, Andrew; Thomas, Anthony W.
2011-03-15
We combine heavy-quark renormalization group arguments with our understanding of the nucleon's wave function to deduce a bound on the gluon polarization {Delta}g in the proton. The bound is consistent with the values extracted from spin experiments at COMPASS and RHIC.
NASA Astrophysics Data System (ADS)
McKinney, Cameron Palmer
In the 1980s, polarized deep inelastic lepton-nucleon scattering experiments revealed that only about a third of the proton's spin of ½ h is carried by the quarks and antiquarks, leaving physicists with the puzzle of how to account for the remaining spin. As gluons carry roughly 50% of the proton's momentum, it seemed most logical to look to the gluon spin as another significant contributor. However, lepton-nucleon scattering experiments only access the gluon helicity distribution, Delta g, through effects on the quark distributions via scaling violations. Constraining Deltag through scaling violations requires experiments that together cover a large range of Q 2. Such experiments had been carried out with unpolarized beams, leaving g(x) (the unpolarized gluon distribution) relatively well-known, but the polarized experiments have only thus far provided weak constraints on Deltag in a limited momentum fraction range. With the commissioning in 2000 of the Relativistic Heavy Ion Collider, the first polarized proton-proton (pp) collider, and the first polarized pp running in 2002, the gluon distributions could be accessed directly by studying quark-gluon and gluon-gluon interactions. In 2009, data from measurements of double longitudinal spin asymmetries, ALL, at the STAR and PHENIX experiments through 2006 were included in a QCD global analysis performed by Daniel de Florian, Rodolfo Sassot, Marco Stratmann, and Werner Vogelsang (DSSV), yielding the first direct constraints on the gluon helicity. The DSSV group found that the contribution of the gluon spin to the proton spin was consistent with zero, but the data provided by PHENIX and STAR was all at mid-rapidity, meaning Delta g was constrained by data only a range in x from 0.05 to 0.2, leaving out helicity contributions from the huge number of low- x gluons. A more recent analysis by DSSV from 2014 including RHIC data through 2009 for the first time points to significant gluon polarization at intermediate
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.
Distribution of aflatoxin M1 in cheese obtained from milk artificially contaminated.
López, C; Ramos, L; Ramadán, S; Bulacio, L; Perez, J
2001-02-28
Small-scale manufacture of cheese using artificially AFM1 contaminated milk as raw material to study the distribution of such toxin both in whey and in cheese, was carried out. Whole milk with undetectable levels of AFM1 was used. The toxin was added in concentration that varied from 1.7 to 2.0 microg/l of milk. After the home-made production of cheese, the concentration of AFM1 was determined both in whey and in cheese, using the enzymatic immunoassay technique. The greatest proportion, 60%, was detected in whey while 40% AFM1 remained in cheese. PMID:11252507
Childress, J F
1986-01-01
The supply of organs and tissues is inadequate to meet the need and demand for transplantation. The article argues for an effective and efficient system for obtaining cadaveric organs that can reduce and perhaps even eliminate scarcity, without violating the principles of justice and respect for persons. The article also examines policies and problems regarding living donors, and analyzes some issues in macroallocation and microallocation. PMID:3331305
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)
Pierrard, V.; Pieters, M.; Lazar, M.; Voitenko, Y.; Lamy, H.; Echim, M.
2014-12-01
Astrophysical and space plasmas are commonly found to be out ofthermal equilibrium, i.e., the velocity distribution functions (VDF)of plasma particles cannot be described well enough by Maxwelliandistribution functions. The suprathermal populations are ubiquitousenhancing the high-energy tail of the distribution. A kinetic model has been developed to successfullydescribe such plasmas with tails decreasing as a power law of thevelocity. In the present work, we show that a natural heating ofsolar and stellar coronas automatically appears when an enhancedpopulation of suprathermal particles is present at low altitude inthe solar (or stellar) atmosphere. This is true not only forelectrons and protons, but also for the minor ions which exhibit atemperature increase proportional to their mass. Moreover,suprathermal electrons contribute to the acceleration of stellarwinds to high bulk velocities when Coulomb collisions are neglected.These results are illustrated by using a global model of the solarcorona and solar wind based on VDF with suprathermal tails for thedifferent particle species. The energetic particles are non-collisional (without Coulomb collisions) even when thermalparticles are submitted to collisions. In the presence of long-rangecorrelations supplied by the fields and plasma instabilities,turbulence can play a role in the generation of such suprathermaltails. Solar wind observations are used as boundary conditions to determine the VDF in the other regions of the heliosphere. Consequences of suprathermal particles are also illustratedfor other space plasmas like the plasmasphere and the polar wind ofthe Earth and other planets.
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.
Shadowing of gluons in perturbative QCD: A comparison of different models
Jalilian-Marian, Jamal; Wang, Xin-Nian
2001-05-01
We investigate the different perturbative QCD-based models for nuclear shadowing of gluons. We show that, in the kinematic region appropriate to the BNL relativistic heavy ion collider experiment, all models give similar estimates for the magnitude of gluon shadowing. At scales relevant to CERN large hadron collider (LHC), there is a sizable difference between the predictions of the different models. However, the uncertainties in gluon shadowing coming from a different parametrization of the gluon distribution in nucleons, are larger than those due to different perturbative QCD models of gluon shadowing. We also investigate the effect of initial nonperturbative shadowing on the magnitude of perturbative shadowing and show that the magnitudes of perturbative and nonperturbative shadowing are comparable at RHIC but perturbative shadowing dominates over nonperturbative shadowing at smaller values of x reached at LHC.
Luszczak, M.; Szczurek, A.
2006-03-01
We discuss and compare different approaches to include gluon transverse momenta for heavy quark-antiquark pair production. The correlations in azimuthal angle and in the heavy quark, heavy antiquark transverse momenta are studied in detail. The results are illustrated with the help of different unintegrated gluon distribution functions (UGDF) from the literature. We compare results obtained with on-shell and off-shell matrix elements and kinematics and quantify where these effects are negligible and where they are essential. We concentrate on the region of asymmetric transverse momenta of charm quark and charm antiquark. Most of UGDFs lead in this corner of the phase space to almost full decorrelation in the azimuthal angle. We propose correlation observables to be best suited in order to test the existing models of UGDFs.
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.
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
Code of Federal Regulations, 2011 CFR
2011-04-01
... 25 Indians 2 2011-04-01 2011-04-01 false May a Tribe/Consortium obtain discretionary or competitive funding that is distributed on a discretionary or competitive basis? 1000.100 Section 1000.100 Indians OFFICE OF THE ASSISTANT SECRETARY, INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ANNUAL FUNDING AGREEMENTS UNDER THE TRIBAL SELF-GOVERNMENT...
Inversion of photometric He+ (30.4 nm) intensities to obtain He+ distributions
NASA Astrophysics Data System (ADS)
Garrido, Dante E.; Smith, Roger W.; Marsh, C. A.; Christensen, Andrew B.; Chakrabarti, Supriya
1993-07-01
Radiation at He(superscript +) at 30.4 nm, which is emitted close to the Earth, comes from three distinct regions; the ionosphere, the plasmasphere and the polar cap. Published observational data on He(superscript +) 30.4 nm have shown that the intensities from polar regions are relatively smaller than the other regions. Polar emissions are believed to be due to resonant scattering of ion outflow in sunlight. A 1982 rocket flight from Poker Flat, Alaska has shown that line-of-sight 30.4 nm emission rates are relatively strong in the direction of the pole. Since the roll of the rocket afforded many different observing directions, we have used the variety of viewing geometries to extract ionospheric source densities from the photometric intensity data. We have assumed that the He(superscript +) densities vary with distance along dipole field lines according to a particular functional form, and then we proceeded to extract the source densities by a matrix inversion method. The results give density variations over a range of latitudes including samples from each of the regions mentioned above. The method obtains good fits of the observed profiles of intensity versus observation angle.
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.
Strongly coupled quark gluon plasma (SCQGP)
NASA Astrophysics Data System (ADS)
Bannur, Vishnu M.
2006-07-01
We propose that the reason for the non-ideal behaviour seen in lattice simulation of quark gluon plasma (QGP) and ultrarelativistic heavy ion collision experiments is that the QGP near Tc and above is a strongly coupled plasma (SCP), i.e., a strongly coupled quark gluon plasma (SCQGP). It is remarkable that the widely used equation of state of SCP in QED (quantum electrodynamics) very nicely fits lattice results on all QGP systems, with proper modifications to include colour degrees of freedom and the running coupling constant. Results on pressure in pure gauge, 2-flavours and 3-flavours QGP can all be explained by treating QGP as SCQGP, as demonstrated here. Energy density and speed of sound are also presented for all three systems. We further extend the model to systems with finite quark mass and reasonably good fits to lattice results are obtained for (2+1)-flavours and 4-flavours QGP. Hence it is a unified model, namely SCQGP, to explain the non-ideal QGP seen in lattice simulations with just two system dependent parameters.
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.
Visvalingam, Jeyachchandran; Wang, Hui; Youssef, Mohamed K; Devos, Julia; Gill, Colin O; Yang, Xianqin
2016-08-01
The objective of this study was to determine the immediate source of Escherichia coli on beef trimmings produced at a large packing plant by analyzing the E. coli on trimmings at various locations of a combo bin filled on the same day and of bins filled on different days. Ten 2,000-lb (907-kg) combo bins (B1 through B10) of trimmings were obtained from a large plant on 6 days over a period of 5 weeks. Thin slices of beef with a total area of approximately 100 cm(2) were excised from five locations (four corners and the center) at each of four levels of the bins: the top surface and 30, 60, and 90 cm below the top. The samples were enriched for E. coli in modified tryptone soya broth supplemented with 20 mg/liter novobiocin. The positive enrichment cultures, as determined by PCR, were plated on E. coli/coliform count plates for recovery of E. coli. Selected E. coli isolates were genotyped using multiple-locus variable-number tandem repeat analysis (MLVA). Of the 200 enrichment cultures, 43 were positive by PCR for E. coli, and 32 of these cultures yielded E. coli isolates. Two bins did not yield any positive enrichment cultures, and three PCR-positive bins did not yield any E. coli isolates. MLVA of 165 E. coli isolates (30, 62, 56, 5, and 12 from B6 through B10, respectively) revealed nine distinct genotypes. MLVA types 263 and 89 were most prevalent overall and on individual days, accounting for 49.1 and 37.6% of the total isolates, respectively. These two genotypes were also found at multiple locations within a bin. All nine genotypes belonged to the phylogenetic group A0 of E. coli, suggesting an animal origin. The finding that the trimmings carried very few E. coli indicates an overall effective control over contamination of beef with E. coli at this processing plant. The lack of strain diversity of the E. coli on trimmings suggests that most E. coli isolates may have come from common sources, most likely equipment used in the fabrication process. PMID:27497119
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.
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.
Gluon Polarization and Jet Production at STAR
Djawotho, Pibero
2009-12-17
I will discuss the most recent measurements of the inclusive jet longitudinal spin asymmetry A{sub LL} in polarized proton-proton collisions. STAR collected its largest data sample thus far, 4.7 pb{sup -1} of integrated luminosity at an average beam polarization of {approx}57%, during the 2006 run at a center-of-mass energy of 200 GeV. I will also present previous STAR inclusive jet A{sub LL} and cross section measurements. The results are compared with theoretical calculations of A{sub LL} based on polarized distribution functions in the nucleon with a range of different contributions from the gluon polarization, {delta}G. The STAR data place significant constraints on {delta}G for 0.02
Jet energy loss in the quark-gluon plasma by stream instabilities
Mannarelli, Massimo; Manuel, Cristina; Gonzalez-Solis, Sergi; Strickland, Michael
2010-04-01
We study the evolution of the plasma instabilities induced by two jets of particles propagating in opposite directions and crossing a thermally equilibrated non-Abelian plasma. In order to simplify the analysis we assume that the two jets of partons can be described with uniform distribution functions in coordinate space and by Gaussian distribution functions in momentum space. We find that while crossing the quark-gluon plasma, the jets of particles excite unstable chromomagnetic and chromoelectric modes. These fields interact with the particles (or hard modes) of the plasma inducing the production of currents; thus, the energy lost by the jets is absorbed by both the gauge fields and the hard modes of the plasma. We compare the outcome of the numerical simulations with the analytical calculation performed assuming that the jets of particles can be described by a tsunamilike distribution function. We find qualitative and semiquantitative agreement between the results obtained with the two methods.
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.
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.
Gluon Contribution To The Nucleon Spin
NASA Astrophysics Data System (ADS)
Arash, Firooz; Taghavi-Shahri, Fatemeh; Shahveh, Abolfazl
2011-07-01
Gluon polarization in Nucleon is evaluated in the valon representation of hadrons. It is shown that although δg/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, Δg(Q2), is sizable. We also notice that the majority of Δg is concentrated at around x = 0.08.
NASA Astrophysics Data System (ADS)
Canon-Tapia, E.; Hamilton, C.; Lopes, R. M. C.
2015-12-01
Clues concerning dynamic aspects of planetary interiors can be obtained through the characterization of volcano distribution at a global scale. On past years, results obtained from global distribution of volcanism on Earth and Venus have been presented, and compared with each other. In this work, the global distribution of volcanism on Io (the innermost of Jupiter's Galilean satellites and the most volcanically active body in the Solar System) is explored using the same tools. Volcanic centers on Io can be divided in two groups: The first including positive thermal anomalies, or hotspots, and the second formed by volcano-tectonic depressions called paterae. Approximately 20% of the documented patera coincide with hotspots, but not all of Io's current volcanic activity is directly associated to paterae. It is uncertain whether hotspots located outside paterae represent volcanic systems still lacking a caldera-like structure, or they represent an entirely different type of volcanism. To account for this source of uncertainty, the analysis reported here was completed on different databases (hotspots, paterae, patera floor units and a combination of hotspots and paterae referred to as volcanic systems). In addition, the distribution of Io's mountains also was studied. As a result, we show that the main clusters of volcanism on Io support the existence of mantle convection patterns that include a combined heating between the astenosphere and the deep mantle (with the former source being more important, but not necessarily on a 2:1 proportion), takes place at moderate to high Reynolds numbers, and includes some degree of impermeability between the astenosphere and the mantle. We also show that although the long-wavelength volcano distribution is controlled by the patterns of mantle convection, the astenosphere serves as a buffer zone where magma is distributed laterally giving place to volcanic activity away from the zones of influence of the hot mantle isotherms. The
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.
Kovner, A.; McLerran, L.; Weigert, H.
1995-10-01
We consider the production of high transverse momentum gluons in the McLerran-Venugopalan model of nuclear structure functions. We explicitly compute the high momentum component in this model. We compute the nuclear target size {ital A} dependence of the distribution of produced gluons.
NASA Astrophysics Data System (ADS)
Kovner, Alex; McLerran, Larry; Weigert, Heribert
1995-10-01
We consider the production of high transverse momentum gluons in the McLerran-Venugopalan model of nuclear structure functions. We explicitly compute the high momentum component in this model. We compute the nuclear target size A dependence of the distribution of produced gluons.
Ordering Multiple Soft Gluon Emissions.
Ángeles Martínez, René; Forshaw, Jeffrey R; Seymour, Michael H
2016-05-27
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. PMID:27284651
Nonperturbative gluon and ghost propagators for d=3 Yang-Mills theory
Aguilar, A. C.; Binosi, D.; Papavassiliou, J.
2010-06-15
We study a manifestly gauge-invariant set of Schwinger-Dyson equations to determine the nonperturbative dynamics of the gluon and ghost propagators in d=3 Yang-Mills theory. The use of the well-known Schwinger mechanism, in the Landau gauge leads to the dynamical generation of a mass for the gauge boson (gluon in d=3), which, in turn, gives rise to an infrared finite gluon propagator and ghost dressing function. The propagators obtained from the numerical solution of these nonperturbative equations are in very good agreement with the results of SU(2) lattice simulations.
On the inclusive gluon jet production from the triple pomeron vertex in the perturbative QCD
NASA Astrophysics Data System (ADS)
Braun, M. A.
2006-11-01
Single and double inclusive cross-sections for gluon jet production from within the triple pomeron vertex are studied in the reggeized gluon technique in the QCD with Nc→∞. It is shown that to satisfy the AGK rules the vertex has to be fully symmetric in all four reggeized gluons which form the two final pomerons. The single inclusive cross-sections are found for different cuttings of the triple pomeron vertex. They sum to the expression obtained by Kovchegov and Tuchin in the color dipole picture. The found double inclusive cross-sections satisfy the AGK rules.
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.
Adare, A.; Bickley, A. A.; Ellinghaus, F.; Glenn, A.; Kinney, E.; Nagle, J. L.; Seele, J.; Wysocki, M.; Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Chi, C. Y.; Cole, B. A.; D'Enterria, D.; Jia, J.
2007-09-01
The PHENIX experiment presents results from the Relativistic Heavy Ion Collider 2005 run with polarized proton collisions at {radical}(s)=200 GeV, for inclusive {pi}{sup 0} production at midrapidity. Unpolarized cross section results are given for transverse momenta p{sub T}=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p{sub T}. The cross section is described well for p{sub T}<1 GeV/c by an exponential in p{sub T}, and, for p{sub T}>2 GeV/c, by perturbative QCD. Double helicity asymmetries A{sub LL} are presented based on a factor of 5 improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton. Using one representative model of gluon polarization it is demonstrated that the gluon spin contribution to the proton spin is significantly constrained.
Consequences Of Fully Dressing Quark-Gluon Vertex Function With Two-Point Gluon Lines
Hrayr Matevosyan; Anthony Thomas; Peter Tandy
2007-06-18
We extend recent studies of the effects of quark-gluon vertex dressing upon the solutions of the Dyson-Schwinger equation for the quark propagator. A momentum delta function is used to represent the dominant infrared strength of the effective gluon propagator so that the resulting integral equations become algebraic. The guark-gluon vertex is constructed from the complete set of diagrams involving only 2-point gluon lines. The additional diagrams, including those with crossed gluon lines, are shown to make an important contribution to the DSE solutions for the quark propagator, because of their large color factors and the rapid growth in their number.
NASA Technical Reports Server (NTRS)
Gerstell, M. F.
1993-01-01
A review of the convolution theorem for obtaining the cumulative k-distribution of a gas mixture proven in Goody et al. (1989) and a discussion of its application to natural spectra are presented. Computational optimizations for use in analyzing high-altitude gas mixtures are introduced. Comparisons of the results of the optimizations, and criteria for deciding what altitudes are 'high' in this context are given. A few relevant features of the testing support software are examined. Some spectrally integrated results, and the circumstances the might permit substituting the method of principal absorbers are examined.
Gluon Spin Contribution to The Nucleon Spin
NASA Astrophysics Data System (ADS)
Arash, Firooz; Shahveh, Abolfazl; Taghavi-Shahri, Fateme
2010-10-01
We have calculated δg/ g in the nucleon at all measured kinematics. The smallness of δg/ g in the measured kinematics should not be interpreted as the the gluon contribution to the nucleon spin is small. In fact the first moment of gluon polarization in the nucleon, Δ g( Q2) can be sizable.
Abrikosov Gluon Vortices in Color Superconductors
NASA Astrophysics Data System (ADS)
Ferrer, Efrain J.
2011-09-01
In this talk I will discuss how the in-medium magnetic field can influence the gluon dynamics in a three-flavor color superconductor. It will be shown how at field strengths comparable to the charged gluon Meissner mass a new phase can be realized, giving rise to Abrikosov's vortices of charged gluons. In that phase, the inhomogeneous gluon condensate anti-screens the magnetic field due to the anomalous magnetic moment of these spin-1 particles. This paramagnetic effect can be of interest for astrophysics, since due to the gluon vortex antiscreening mechanism, compact stars with color superconducting cores could have larger magnetic fields than neutron stars made up entirely of nuclear matter. I will also discuss a second gluon condensation phenomenon connected to the Meissner instability attained at moderate densities by two-flavor color superconductors. In this situation, an inhomogeneous condensate of charged gluons emerges to remove the chromomagnetic instability created by the pairing mismatch, and as a consequence, the charged gluonic currents induce a magnetic field. Finally, I will point out a possible relation between glitches in neutron stars and the existence of the gluon vortices.
NASA Astrophysics Data System (ADS)
Bailey, Justin J.
Exospheric atomic hydrogen (H) resonantly scatters solar Lyman-alpha (121.567 nm) radiation, observed as the glow of the geocorona. Measurements of scattered solar photons allow one to probe time-varying three-dimensional distributions of exospheric H atoms. The Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission images the magnetosphere in energetic neutral atom (ENA) fluxes and additionally carries Lyman-alpha Detectors (LADs) to register line-of-sight intensities of the geocorona. This work details a process for preparing TWINS data such that LAD measurements can be used to obtain global H density distributions with three-dimensional asymmetries above 3 earth radii. Sequences of distributions are presented to investigate the dynamic exosphere, responding to seasonal variations between a summer solstice and autumnal equinox, as well as to solar and geomagnetic variations as described by commonly used indices. The distributions reveal asymmetries from day to night, north to south, and dawn to dusk. A nightside extension persists that is consistent with the location of a geotail. A seasonal north-south asymmetry occurs as solar illumination differs between the summer and winter polar regions. Pole-equator and less pronounced dawn-dusk asymmetries also appear, possibly due to a coupling effect via charge exchange with the polar wind and plasmasphere, respectively. A common phenomenon in geospace occurs as magnetospheric energetic ions collide with neutral background atoms and produce ENAs that, no longer bound by Earth's magnetic field, can travel large distances though space with minimal disturbance ---providing an opportunity for remote detection. Knowledge of the distribution of the primary neutral partner, exospheric H atoms, is therefore essential for the interpretation of ENA fluxes and subsequent retrieval of ion densities. An analysis is summarized that demonstrates the importance of exospheric H density distributions on reconstructing
Quark and gluon decay functions in QCD and recombination model
Change, V.; Hwa, R.C.
1980-04-01
Inclusive longitudinal-momentum distributions of pions in jets initiated by quarks and gluons are determined in perturbative QCD and recombination model. The quark and antiquark joint distributions in jets are first calculated in the leading-order approximation at high Q/sup 2/. Gluons in the jets are completely converted to quark pairs. From the overall distribution q anti q pairs with definite quantum numbers then recombine to form pions. The recombination function for the process is well determined in the valon model. No adjustable parameters are involved in these calculations, and no data at low Q/sup 2/ are used as phenomenological input. The result for the quark decay functions can be compared with data on e/sup +/e/sup -/ annihilation, and the agreement is very good in both shape and normalization. Predictions for the gluon decay functions are presented, but they cannot yet be checked by experiments. The x and Q/sup 2/ dependences of both types of decay functions have been parametrized in simple form suitable for use in theoretical and experimental applications. 17 figures, 1 table.
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. PMID:24116766
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.
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
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.
Froissart bound and gluon number fluctuations
Xiang Wenchang
2010-05-01
We study the effect of gluon number fluctuations (Pomeron loops) on the impact parameter behavior of the scattering amplitude in the fixed coupling case. We demonstrate that the dipole-hadron cross section computed from gluon number fluctuations saturates the Froissart bound and the growth of the radius of the black disk with rapidity is enhanced by an additional term as compared to the single event case. We find that the physical amplitude has a Gaussian impact parameter dependence once the gluon number fluctuations are included. This indicates that the fluctuations may be the microscopic origin for the Gaussian impact parameter dependence of the scattering amplitude.
Quark and gluon condensates in isospin matter
He Lianyi; Jiang Yin; Zhuang Pengfei
2009-04-15
By applying the Hellmann-Feynman theorem to a charged pion gas, the quark and gluon condensates at low isospin density are determined by precise pion properties. At intermediate density around f{sub {pi}}{sup 2}m{sub {pi}}, from both the estimation for the dilute pion gas and the calculation with the Nambu-Jona-Lasinio model, the quark condensate is strongly and monotonously suppressed, while the gluon condensate is enhanced and can be larger than its vacuum value. This unusual behavior of the gluon condensate is universal for Bose condensed matter of mesons. Our results can be tested by lattice calculations at finite isospin density.
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.
The Gluon Contribution to the Sivers Effect COMPASS results
NASA Astrophysics Data System (ADS)
Kurek, Krzysztof; Szabelski, Adam
2016-02-01
The Sivers effect describes the correlation between the spin of the nucleon and the orbital motion of partons. It can be measured via Semi-Inclusive Deep Inelastic Scattering of lepton on a transversely polarised proton and deuteron targets by determining the azimuthal asymmetry related to the modulation in the Sivers angle ϕSiv. In the paper a method of obtaining the Sivers asymmetry for gluons is presented. It is based on the model of lepton nucleon interactions via three single-photon-exchange processes: photon-gluon fusion (PGF), QCD Compton (QCDC) and leading process (LP). A method of simultaneous extraction of the Sivers asymmetries of the three processes with the use of Monte Carlo (MC) and neural networks (NN) approach is presented. The method has been applied to COMPASS data taken with 160GeV/c muon beam scattered off transversely polarised deuteron and transversely polarised proton target. For each target a data sample of events containing at least two hadrons with large transverse momentum has been selected. Finally the results for gluon Sivers asymmetry were obtained to be: Adg = -0.14 ± 0.15(stat.) ± 0.06(syst.) at
Higgs boson production via gluon fusion: Soft-gluon resummation including mass effects
NASA Astrophysics Data System (ADS)
Schmidt, Timo; Spira, Michael
2016-01-01
We analyze soft and collinear gluon resummation effects at the N3LL level for Standard Model Higgs boson production via gluon fusion g g →H and the neutral scalar and pseudoscalar Higgs bosons of the minimal supersymmetric extension at the next-to-next-to-next-to-leading-log (N3LL ) and next-to-next-to-leading-log (NNLL) level, respectively. We introduce refinements in the treatment of quark mass effects and subleading collinear gluon effects within the resummation. Soft and collinear gluon resummation effects amount to up to about 5% beyond the fixed-order results for scalar and pseudoscalar Higgs boson production.
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.
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.
Initial Gluon Multiplicity in Heavy-Ion Collisions
Krasnitz, Alex; Venugopalan, Raju
2001-02-26
The initial gluon multiplicity per unit area per unit rapidity, dN/L{sup 2}/d{eta} , in high energy nuclear collisions, is equal to f{sub N}(g{sup 2}{mu}L) (g{sup 2}{mu}){sup 2}/g{sup 2 } , with {mu}{sup 2} proportional to the gluon density per unit area of the colliding nuclei. For an SU(2) gauge theory, we compute f{sub N}(g{sup 2}{mu}L)=0.14{+-} 0.01 for a wide range in g{sup 2}{mu}L . Extrapolating to SU(3), we predict dN/L{sup 2}/d{eta} for values of g{sup 2}{mu}L relevant to the Relativistic Heavy Ion Collider and the Large Hadron Collider. We compute the initial gluon transverse momentum distribution, dN/L{sup 2}/d{sup 2}k{sub {perpendicular}} , and show it to be well behaved at low k{sub {perpendicular}} .
Bulk Properties and Collective Flow of Quark Gluon Plasma
NASA Astrophysics Data System (ADS)
Kapusta, Joseph
2007-10-01
Quantum Chromodynamics predicts a transition from a hadronic phase at temperatures less than 150-200 MeV to a quark gluon plasma phase at higher temperatures. Lattice calculations show a big increase in the entropy density in this vicinity. Whether the transition is first or second order or a smooth rapid crossover depends upon the values of the up, down and strange quark masses. The goal of the heavy ion experimental program at RHIC is to observe this transition and to study the nature of the quark gluon plasma quantitatively. Two big surprises arose from these experiments: Substantial collective flow has been observed, as evidenced by single-particle transverse momentum distributions and by azimuthal correlations among the produced particles, and the degree to which high energy jets are attenuated in the produced matter. A variety of theoretical models of these collisions require initial energy densities more than a factor of 10 greater than in neutron star cores and more than a factor of 100 greater than within atomic nuclei. Taken together this body of work implies a strongly interacting phase of quarks and gluons beyond the capabilities of perturbation theory. This has motivated approaches based on gauge theories with gravity duals where physical observables may be calculated in a strong coupling limit. This in turn has stimulated interest from members of the string theory community who are currently bringing their expertise to bear on the problem.
Pennington, M. R.; Wilson, D. J.
2011-11-01
The gluon and ghost propagators in Landau gauge QCD are investigated using the Schwinger-Dyson equation approach. Working in Euclidean spacetime, we solve for these propagators using a selection of vertex inputs, initially for the ghost equation alone and then for both propagators simultaneously. The results are shown to be highly sensitive to the choices of vertices. We favor the infrared finite ghost solution from studying the ghost equation alone where we argue for a specific unique solution. In order to solve this simultaneously with the gluon using a dressed-one-loop truncation, we find that a nontrivial full ghost-gluon vertex is required in the vanishing gluon momentum limit. The self-consistent solutions we obtain correspond to having a masslike term in the gluon propagator dressing, in agreement with similar studies supporting the long-held proposal of Cornwall.
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.
Generalized Valon Model for Double Parton Distributions
NASA Astrophysics Data System (ADS)
Broniowski, Wojciech; Ruiz Arriola, Enrique; Golec-Biernat, Krzysztof
2016-03-01
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.
The mass distribution of CL0939+4713 obtained from a `weak' lensing analysis of a WFPC2 image.
NASA Astrophysics Data System (ADS)
Seitz, C.; Kneib, J.-P.; Schneider, P.; Seitz, S.
1996-10-01
The image distortions of high-redshift galaxies caused by gravitational light deflection of foreground clusters of galaxies can be used to reconstruct the two-dimensional surface mass density of these clusters. We apply an unbiased parameter-free reconstruction technique to the cluster CL0939+4713 (Abell 851), observed with the WFPC2 on board of the HST. We demonstrate that a single deep WFPC2 observation can be used for cluster mass reconstruction despite its small field of view and the irregular shape of the data field (especially for distant clusters). For CL0939, we find a strong correlation between the reconstructed mass distribution and the bright cluster galaxies indicating that mass follows light on average. The detected anti-correlation between the faint galaxies and the reconstructed mass is most likely an effect of the magnification (anti) bias, which was detected previously in the cluster A1689. Because of the high redshift of CL0939 (z_d_=0.41), the redshift distribution of the lensed, faint galaxies has to be accounted for in the reconstruction technique. We derive an approximate global transformation for the surface mass density which leaves the mean image ellipticities invariant, resulting in an uncertainty in the normalization of the mass. From the non-negativity of the surface mass density, we derive lower limits on the mass inside the observed field of 0.75(h^-1^_50_Mpc)^2^ ranging from M>3.6x10^14^h^-1^_50_Msun_ to M>6.3x10^14^h^-1^_50_Msun_ for a mean redshift of
Gluon Productions in classical SU(3) lattice gauge theory in high energy heavy ion collisions
NASA Astrophysics Data System (ADS)
Nara, Yasushi; Krasnitz, Alex; Venugopalan, Raju
2001-10-01
A classical effective field theory approach was introduced to describe the initial conditions for the produced partons in ultra-relativistic heavy ion collisions. The importance of the productions of small x gluons are emphasized, since, in high energy heavy ion collisions, parton distributions grow rapidly and may saturate. Most of them are freed during the reactions. Krasnitz and Venugopalan performed a non-perturbative numerical computation for a SU(2) gauge theory. We present the initial gluon transverse momentum distribution from SU(3) real time lattice gauge simulation in the high energy heavy ion collisions.
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
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.
Uribe, D; Martinez, W; Cerón, J
2003-02-01
Colombia is a tropical country located at the north of South America. It is considered to be one of the most important countries in terms of its biodiversity worldwide. One hundred and eight soil samples obtained from agricultural crops and wild ecosystems were evaluated in terms of the presence of Bacillus thuringiensis (Bt) native strains. One hundred and eight different Bt strains were isolated and characterized by the presence of crystal proteins by SDS-PAGE and a multiplex PCR with general and specific primers for cry1 and cry3, cry7, and cry8 gene detection. Most of the Bt strains (73%) reacted with the cry1 general primers; 27.8% of the Bt strains reacted with cry3, cry7, and cry8 general primers and 17.8% of strains did not react with any of these two sets of primers. Thirty different PCR profiles were found in the strains with cry1 genes when they were analyzed with specific primers (cry1A to cry1F). A high frequency of joint occurrence was observed for cry1Aa/cry1Ab, cry1Aa/cry1Ac, cry1Ab/cry1Ac, and cry1C/cry1D genes with a Pearson coefficient of 0.88, 0.74, 0.76, and 0.87, respectively. Other distinctive characteristics were found in the Colombian collection as the presence of 22.2% of native strains which presented, at the same time, lepidopteran and coleopteran active genes. Interesting relations were found as well between the cry gene distribution and the geographical areas sampled. Finally, some strains with moderate to high biopesticide activity against Spodoptera frugiperda (Lepidoptera) and Premnotrypes vorax (Coleoptera) insects were identified, this being important to explore future microbial strategies for the control of these crop pests in the region. PMID:12623312
Bjoraker, Jefferson; Venugopalan, Raju
2001-02-01
The initial distribution of gluons at the very early times after a high-energy heavy ion collision is described by the bulk scale Q{sub s} of gluon saturation in the nuclear wave function. The subsequent evolution of the system towards kinetic equilibrium is described by a nonlinear Landau equation for the single particle distributions [A. H. Mueller, Nucl. Phys. B572, 227 (2000); Phys. Lett. B 475, 220 (2000)]. In this paper, we solve this equation numerically for the idealized initial conditions proposed by Mueller, and study the evolution of the system to equilibrium. We discuss the sensitivity of our results on the dynamical screening of collinear divergences. In a particular model of dynamical screening, the convergence to the hydrodynamic limit is seen to be rapid relative to hydrodynamic time scales. The equilibration time, the initial temperature, and the chemical potential are shown to have a strong functional dependence on the initial gluon saturation scale Q{sub s}.
Dynamical equation of the effective gluon mass
Aguilar, A. C.; Binosi, D.; Papavassiliou, J.
2011-10-15
In this article, we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding ''one-loop dressed'' Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rather stringent constraint on the derivative of the gluonic dressing function, which is comfortably satisfied by the large-volume lattice data for the gluon propagator, both for SU(2) and SU(3). The numerical treatment of the mass equation, under some simplifying assumptions, is presented for the aforementioned gauge groups, giving rise to a gluon mass that is a nonmonotonic function of the momentum. Various theoretical improvements and possible future directions are briefly discussed.
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. PMID:27554145
Ion-induced quark-gluon implosion.
Frankfurt, L; Strikman, M
2003-07-11
We investigate nuclear fragmentation in the central proton-nucleus and nucleus-nucleus collisions at the energies of CERN LHC. Within the semiclassical approximation we argue that because of the fast increase with energy of the cross sections of soft and hard interactions each nucleon is stripped in the average process off "soft" partons and fragments into a collection of leading quarks and gluons with large p(t). Valence quarks and gluons are streaming in the opposite directions when viewed in the c.m. of the produced system. The resulting pattern of the fragmentation of the colliding nuclei leads to an implosion of the quark and gluon constituents of the nuclei. The nonequilibrium state produced at the initial stage in the nucleus fragmentation region is estimated to have densities >/=50 GeV/fm(3) at the LHC energies and probably >/=10 GeV/fm(3) at BNL RHIC. PMID:12906475
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...
NASA Technical Reports Server (NTRS)
Peters, B. C., Jr.; Walker, H. F.
1975-01-01
A general iterative procedure is given for determining the consistent maximum likelihood estimates of normal distributions. In addition, a local maximum of the log-likelihood function, Newtons's method, a method of scoring, and modifications of these procedures are discussed.
Quark-gluon plasma in an external magnetic field.
Levkova, L; DeTar, C
2014-01-10
Using numerical simulations of lattice QCD we calculate the effect of an external magnetic field on the equation of state of the quark-gluon plasma. The results are obtained using a Taylor expansion of the pressure with respect to the magnetic field for the first time. The coefficients of the expansion are computed to second order in the magnetic field. Our setup for the external magnetic field avoids complications arising from toroidal boundary conditions, making a Taylor series expansion straightforward. This study is exploratory and is meant to serve as a proof of principle. PMID:24483888
High multiplicity study and gluon dominance model
NASA Astrophysics Data System (ADS)
Kokoulina, E. S.
2016-01-01
Study of high multiplicity events in proton-proton interactions is carried out at the U-70 accelerator (IHEP, Protvino). These events are extremely rare. Usually, Monte Carlo codes underestimate topological cross sections in this region. The gluon dominance model (GDM) was offered to describe them. It is based on QCD and a phenomenological scheme of a hadronization stage. This model indicates a recombination mechanism of hadronization and a gluon fission. Future program of the SVD Collaboration is aimed at studying a long-standing puzzle of excess soft photon yield and its connection with high multiplicity at the U-70 and Nuclotron facility at JINR, Dubna.
NASA Astrophysics Data System (ADS)
Pierrard, V.; Pieters, M.
2014-12-01
Astrophysical and space plasmas are commonly found to be out of thermal equilibrium; i.e., the velocity distribution functions of their particles are not well described by Maxwellian distributions. They generally have more suprathermal particles in the tail of the distribution. The kappa distribution provides a generalization to successfully describe such plasmas with tails decreasing as a power law of the velocity. In the present work, we improve the solar wind model developed on the basis of such kappa distributions by incorporating azimuthally varying 1 AU boundary conditions to produce a spatially structured view of the solar wind expansion. By starting from the top of the chromosphere to the heliosphere and by applying relevant boundary conditions in the ecliptic plane, a global model of the corona and the solar wind is developed for each particle species. The model includes the natural heating of the solar corona automatically appearing when an enhanced population of suprathermal particles is present at low altitude in the solar (or stellar) atmosphere. This applies not only for electrons and protons but also for the minor ions which then have a temperature increase proportional to their mass. Moreover, the presence of suprathermal electrons contributes to the acceleration of the solar wind to high bulk velocities when Coulomb collisions are neglected. The results of the model are illustrated in the solar corona and in solar wind for the different particle species and can now be directly compared in two dimensions with spacecraft observations in the ecliptic plane.
Gomez-Alvarez, Vicente; 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
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...
NASA Astrophysics Data System (ADS)
Krasnitz, Alex; Nara, Yasushi; Venugopalan, Raju
2003-04-01
We extend previous work on high energy nuclear collisions in the Color Glass Condensate model to study collisions of finite ultrarelativistic nuclei. The changes implemented include (a) imposition of color neutrality at the nucleon level and (b) realistic nuclear matter distributions of finite nuclei. The saturation scale characterizing the fields of color charge is explicitly position-dependent, Λs= Λs( xT). We compute gluon distributions both before and after the collisions. The gluon distribution in the nuclear wavefunction before the collision is significantly suppressed below the saturation scale when compared to the simple McLerran-Venugopalan model prediction, while the behavior at large momentum pT≫ Λs remains unchanged. We study the centrality dependence of produced gluons and compare it to the centrality dependence of charged hadrons exhibited by the RHIC data. We demonstrate the geometrical scaling property of the initial gluon transverse momentum distributions for different centralities. Classical Yang-Mills results for pT< Λs are simply matched to perturbative QCD computations for pT> Λs—the resulting energy per particle is significantly lower than the purely classical estimates. Our results for nuclear collisions can be used as initial conditions for quantitative studies of the further evolution and possible equilibration of hot and dense gluonic matter produced in heavy ion collisions. Finally, we study pA collisions within the classical framework. Our results agree well with previously derived analytical results in the appropriate kinematical regions.
Bound-state quark and gluon contributions to structure functions in QCD
Brodsky, S.J.
1990-08-01
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic bound-valence'' and extrinsic non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs.
SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition
Ilgenfritz, Ernst-Michael; Menz, Christoph; Mueller-Preussker, Michael; Schiller, Arwed; Sternbeck, Andre
2011-03-01
We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of the associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory.
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…
Sambamurti Memorial Lecture: Spotlight on the Gluon
Michael Begelas
2010-09-01
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.
Quark-gluon plasma (Selected Topics)
Zakharov, V. I.
2012-09-15
Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.
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.
NASA Astrophysics Data System (ADS)
Li, Mengnan; Tan, Liying; Ma, Jing; Yu, Siyuan; Yang, Qingbo; Wu, Jiajie
2016-05-01
Based on the characteristics of the laser device and the inevitable error of the processing technique, a laser beam emitted from a communication terminal can be represented by the Gaussian Schell model (GSM). In space-to-ground link laser communications, the optical intensity is affected by the source coherence parameter and the zenith angle. With full consideration of these two parameters, the statistical distribution model of the optical intensity with a GSM laser in both downlink and uplink is derived. The simulation results indicate that increasing the source coherence parameter has an effect on the statistical distribution of the optical intensity; this effect is highly similar to the effect of a larger zenith angle. The optical intensity invariably degrades with increasing source coherence parameter or zenith angle. The results of this work can promote the improvement of the redundancy design of a laser communication receiver system.
NASA Astrophysics Data System (ADS)
Anikeev, A. A.; Bogdanova, Yu. A.; Gubin, S. A.
Multicomponent hypernetted-chain/soft core mean spherical approximation (HMSA) was shown to be successfully applied for the problem of ambidextrous attractive/repulsive interaction simulation in dense fluids like shock compression products of CxNyOz liquid systems. This approximation provides high numerical accuracy for thermodynamic quantities due to its self-consistency. In addition, distribution function integral equation theory (DFIET) doesn't require chemical equilibrium for simulated systems. Reproducible shock Hugoniot curves verify the macroscopic properties such as pressure and internal energy. Radial distribution function analysis, proposed in this paper, approves macroscopic and microscopic/structural short-range order properties both by molecular Monte-Carlo (MC) method for multicomponent dissociation products of liquid CO2 up to 160 GPa.
NASA Astrophysics Data System (ADS)
Rousset, J.-G.; Kobak, J.; Janik, E.; Parlinska-Wojtan, M.; Slupinski, T.; Golnik, A.; Kossacki, P.; Nawrocki, M.; Pacuski, W.
2016-05-01
We report on the optical properties of structures containing self assembled CdTe quantum dots (QDs) combined with Te and Se based distributed Bragg reflectors either in a half cavity geometry with a relatively broad cavity mode or in a full cavity geometry where the cavity mode is much narrower. We show that for both structures the extraction coefficient of the light emitted from the QDs ensemble is enhanced by more than one order of magnitude with respect to the QDs grown on a ZnTe buffer. However, a single QD line broadening is observed and attributed to an unintentional incorporation of Se in the vicinity of the CdTe QDs. We show that postponing the QDs growth for 24 h after the distributed Bragg reflector deposition allows recovering sharp emission lines from individual QDs. This two step growth method is proven to be efficient also for the structures with CdTe QDs containing a single Mn2+ ion.
Hybrid neutron stars with the Dyson-Schwinger quark model and various quark-gluon vertices
NASA Astrophysics Data System (ADS)
Chen, H.; Wei, J.-B.; Baldo, M.; Burgio, G. F.; Schulze, H.-J.
2015-05-01
We study cold dense quark matter and hybrid neutron stars with a Dyson-Schwinger quark model and various choices of the quark-gluon vertex. We obtain the equation of state of quark matter in beta equilibrium and investigate the hadron-quark phase transition in combination with a hadronic equation of state derived within the Brueckner-Hartree-Fock many-body theory. Comparing with the results for quark matter within the rainbow approximation, the Ball-Chiu (BC) Ansatz and the 1BC Ansatz for the quark-gluon vertex lead to a reduction of the effective interaction at finite chemical potential, qualitatively similar to the effect of our gluon propagator. We find that the phase transition and the equation of state of the quark or mixed phase and consequently the resulting hybrid star mass and radius depend mainly on a global reduction of the effective interaction due to effects of both the quark-gluon vertex and gluon propagator, but are not sensitive to details of the vertex Ansatz.
Thermalization of mini-jets in a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Iancu, Edmond; Wu, Bin
2015-10-01
We complete the physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma by investigating the thermalization of the soft components of the jet. We argue that the following scenario should hold: the leading particle emits a significant number of mini-jets which promptly evolve via quasi-democratic branchings 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. We support this scenario, first, via parametric arguments and, next, by studying a simplified kinetic equation, which describes the jet dynamics in longitudinal phase-space. We solve the kinetic equation using both (semi-)analytical and numerical methods. In particular, we obtain the first exact, analytic, solutions to the ultrarelativistic Fokker-Planck equation in one-dimensional phase-space. Our results confirm the physical picture aforementioned and demonstrate the quenching of the jet via multiple branching followed by the thermalization of the soft gluons in the cascades.
NASA Astrophysics Data System (ADS)
Greif, Moritz; Bouras, Ioannis; Greiner, Carsten; Xu, Zhe
2014-11-01
Electric conductivity is sensitive to effective cross sections among the particles of the partonic medium. We investigate the electric conductivity of a hot plasma of quarks and gluons, solving the relativistic Boltzmann equation. In order to extract this transport coefficient, we employ the Green-Kubo formalism and, independently, a method motivated by the classical definition of electric conductivity. To this end we evaluate the static electric diffusion current upon the influence of an electric field. Both methods give identical results. For the first time, we obtain numerically the Drude electric conductivity formula for an ultrarelativistic gas of quarks and gluons employing constant isotropic binary cross sections. Furthermore, we extract the electric conductivity for a system of massless quarks and gluons including screened binary and inelastic, radiative 2 ↔3 perturbative QCD scattering. Comparing with recent lattice results, we find an agreement in the temperature dependence of the conductivity.
A T-matrix calculation for in-medium heavy-quark gluon scattering
NASA Astrophysics Data System (ADS)
Huggins, K.; Rapp, R.
2012-12-01
The interactions of charm and bottom quarks in a quark-gluon plasma (QGP) are evaluated using a thermodynamic 2-body T-matrix. We specifically focus on heavy-quark (HQ) interactions with thermal gluons with an input potential motivated by lattice-QCD computations of the HQ free energy. The latter is implemented into a field-theoretic ansatz for color-Coulomb and (remnants of) confining interactions. This, in particular, enables to discuss corrections to the potential approach, specifically hard-thermal-loop corrections to the vertices, relativistic corrections deduced from pertinent Feynman diagrams, and a suitable projection on transverse thermal gluons. The resulting potentials are applied to compute scattering amplitudes in different color channels and utilized for a calculation of the corresponding HQ drag coefficient in the QGP. A factor of ˜2-3 enhancement over perturbative results is obtained, mainly driven by the resummation in the attractive color-channels.
Analytic Structure of the Landau-Gauge Gluon Propagator
NASA Astrophysics Data System (ADS)
Strauss, Stefan; Fischer, Christian S.; Kellermann, Christian
2012-12-01
The analytic structure of the nonperturbative gluon propagator contains information on the absence of gluons from the physical spectrum of the theory. We study this structure from numerical solutions in the complex momentum plane of the gluon and ghost Dyson-Schwinger equations in Landau gauge Yang-Mills theory. The resulting ghost and gluon propagators are analytic apart from a distinct cut structure on the real, timelike momentum axis. The propagator violates the Osterwalder-Schrader positivity condition, confirming the absence of gluons from the asymptotic spectrum of the theory.
Analytic structure of the Landau-gauge gluon propagator.
Strauss, Stefan; Fischer, Christian S; Kellermann, Christian
2012-12-21
The analytic structure of the nonperturbative gluon propagator contains information on the absence of gluons from the physical spectrum of the theory. We study this structure from numerical solutions in the complex momentum plane of the gluon and ghost Dyson-Schwinger equations in Landau gauge Yang-Mills theory. The resulting ghost and gluon propagators are analytic apart from a distinct cut structure on the real, timelike momentum axis. The propagator violates the Osterwalder-Schrader positivity condition, confirming the absence of gluons from the asymptotic spectrum of the theory. PMID:23368451
NASA Astrophysics Data System (ADS)
Sarrico, C. O. R.
2015-10-01
The system of conservation laws {u_t} + {( {{{u^2} + {v^2}}/2} )_x} = 0, v t + ( uv - v)x = 0 with the initial conditions u( x, 0) = l 0 + b 0 H( x), v( x, 0) = k 0 + c 0 H( x), where H is the Heaviside function is studied. This strictly hyperbolic system was introduced by M. Brio in 1988 and provides a simplified model for the magnetohydrodynamics equations. Under certain compatibility conditions for the constants l 0, b 0, k 0, c 0, an explicit solution containing a Dirac mass is given and we prove the uniqueness of this solution within a convenient class of distributions which includes Dirac-delta measures. Our concept of solution is defined within the framework of a distributional product, and it is a consistent extension of the concept of a classical solution. This direct method seems considerably simpler than the weak asymptotic method usually used in the study of delta-shocks emergence in nonlinear conservation laws.
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.
The Fluid Nature of Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Zajc, W. A.
2008-06-01
Collisions of heavy nuclei at very high energies offer the exciting possibility of experimentally exploring the phase transformation from hadronic to partonic degrees of freedom which is predicted to occur at several times normal nuclear density and/or for temperatures in excess of ˜170MeV. Such a state, often referred to as a quark-gluon plasma, is thought to have been the dominant form of matter in the universe in the first few microseconds after the Big Bang. Data from the first five years of heavy ion collisions of Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) clearly demonstrate that these very high temperatures and densities have been achieved. While there are strong suggestions of the role of quark degrees of freedom in determining the final-state distributions of the produced matter, there is also compelling evidence that the matter does not behave as a quasi-ideal state of free quarks and gluons. Rather, its behavior is that of a dense fluid with very low kinematic viscosity exhibiting strong hydrodynamic flow and nearly complete absorption of high momentum probes. The current status of the RHIC experimental studies is presented, with a special emphasis on the fluid properties of the created matter, which may in fact be the most perfect fluid ever studied in the laboratory.
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.
Running coupling corrections to inclusive gluon production
NASA Astrophysics Data System (ADS)
Horowitz, W. A.; Kovchegov, Y. V.
2011-12-01
We calculate running coupling corrections for the lowest-order gluon production cross section in high energy hadronic and nuclear scattering using the BLM scale-setting prescription. At leading order, there are three powers of fixed coupling; in our final answer, these three couplings are replaced by seven factors of running coupling: five in the numerator and two in the denominator, forming a 'septumvirate' of running couplings, analogous to the 'triumvirate' of running couplings found earlier for the small-x BFKL/BK/JIMWLK evolution equations. It is interesting to note that the two running couplings in the denominator of the 'septumvirate' run with complex-valued momentum scales, which are complex conjugates of each other, such that the production cross section is indeed real. We use our lowest-order result to conjecture how running coupling corrections may enter the full fixed-coupling kT-factorization formula for gluon production which includes nonlinear small-x evolution.
Inaba, Tohru; Yuki, Yoichi; Yuasa, Soichi; Fujita, Naohisa; Yoshitomi, Kazue; Kamisako, Toshinori; Torii, Kunio; Okada, Toshiharu; Urasaki, Yoshimasa; Ueda, Takanori; Tohyama, Kaoru
2011-08-01
We evaluated the diagnostic utility of peripheral blood neutrophil distribution patterns obtained using the CELL-DYN SAPPHIRE hematology analyzer in patients with myelodysplastic syndrome (MDS). Peripheral blood was obtained from 467 individuals including 32 patients with MDS, and the respective neutrophil distribution patterns were observed using two light scatters [7-degree complexity (7D) and 90-degree lobularity (90D)]. These scattering intensities are shown as median (median neutrophil distribution: MND) and coefficient of variation (neutrophil distribution width: NDW). Generally, MDS patients showed lower 7D MND, higher 7D NDW, lower 90D MND and higher 90D NDW than other comparable groups. Whereas 90D parameters were more diagnostically efficient than 7D ones in patients with MDS. The sensitivity and specificity of 90D MND for MDS patients became 78.1 and 78.9%, respectively (cut-off value = 14,514). 90D NDW was most diagnostically effective with 87.5% sensitivity and 91.0% specificity (cut-off value = 21.2%). Both 90D parameters showed no evident correlation with the degree of either leukocytopenia or peripheral blood dysgranulopoiesis. In conclusion, neutrophil distribution parameters, especially 90D NDW, appear to provide convenient and objective markers for the screening of patients with MDS in routine laboratory hematology. PMID:21732036
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.
Hatta, Yoshitaka; Xiao, Bo-Wen; Yuan, Feng
2016-05-20
We investigate the close connection between the quantum phase space Wigner distribution of small-x gluons and the color dipole scattering amplitude, and we propose studying it experimentally in the hard diffractive dijet production at the planned electron-ion collider. The angular correlation between the nucleon recoiled momentum and the dijet transverse momentum probes the nontrivial correlation in the phase space Wigner distribution. This experimental study not only provides us with three-dimensional tomographic pictures of gluons inside high energy protons-it gives a unique and interesting signal for the small-x dynamics with QCD evolution effects. PMID:27258865
Gluon spectrum in the glasma from JIMWLK evolution
NASA Astrophysics Data System (ADS)
Lappi, T.
2011-09-01
The JIMWLK equation with a "daughter dipole" running coupling is solved numerically, starting from an initial condition given by the McLerran-Venugopalan model. The resulting Wilson line configurations are then used to compute the spectrum of gluons comprising the glasma initial state of a high energy heavy ion collision. The development of a geometrical scaling region makes the spectrum of produced gluons harder. Thus the ratio of the mean gluon transverse momentum to the saturation scale grows with energy. Also the total gluon multiplicity increases with energy slightly faster than the saturation scale squared.
Semirelativistic potential model for three-gluon glueballs
Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard
2008-05-01
The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Our results are in good agreement with other approaches and lattice calculation for the odderon trajectory but differ strongly from lattice in the J{sup +-} sector. We propose a possible explanation for this problem.
NASA Astrophysics Data System (ADS)
Gonçalves, V. P.; Martins, L. A. S.; Sauter, W. K.
2016-02-01
The current uncertainty on the gluon density extracted from the global parton analysis is large in the kinematical range of small values of the Bjorken- x variable and low values of the hard scale Q^2. An alternative to reduces this uncertainty is the analysis of the exclusive vector meson photoproduction in photon-hadron and hadron-hadron collisions. This process offers a unique opportunity to constrain the gluon density of the proton, since its cross section is proportional to the gluon density squared. In this paper we consider current parametrisations for the gluon distribution and estimate the exclusive vector meson photoproduction cross section at HERA and LHC using the leading logarithmic formalism. We perform a fit of the normalisation of the γ h cross section and the value of the hard scale for the process and demonstrate that the current LHCb experimental data are better described by models that assume a slow increasing of the gluon distribution at small x and low Q^2.
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.
Clouvas, A; Xanthos, S; Antonopoulos-Domis, M; Silva, J
1998-02-01
A Monte Carlo based method for the conversion of an in-situ gamma-ray spectrum obtained with a portable Ge detector to photon flux energy distribution is proposed. The spectrum is first stripped of the partial absorption and cosmic-ray events leaving only the events corresponding to the full absorption of a gamma ray. Applying to the resulting spectrum the full absorption efficiency curve of the detector determined by calibrated point sources and Monte Carlo simulations, the photon flux energy distribution is deduced. The events corresponding to partial absorption in the detector are determined by Monte Carlo simulations for different incident photon energies and angles using the CERN's GEANT library. Using the detector's characteristics given by the manufacturer as input it is impossible to reproduce experimental spectra obtained with point sources. A transition zone of increasing charge collection efficiency has to be introduced in the simulation geometry, after the inactive Ge layer, in order to obtain good agreement between the simulated and experimental spectra. The functional form of the charge collection efficiency is deduced from a diffusion model. PMID:9450590
Leading order determination of the gluon polarisation from DIS events with high-pT hadron pairs
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.; Bernhard, J.; Bertini, R.; Bettinelli, M.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Burtin, E.; Chaberny, D.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Das, S.; Dasgupta, S. 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.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gazda, R.; 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.; Hedicke, S.; 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.; 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.; Le Goff, J.-M.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Matsuda, T.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Moinester, M. A.; Morreale, A.; Mutter, A.; Nagaytsev, A.; Nagel, T.; Nassalski, J. P.; 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.; Pontecorvo, G.; Pretz, J.; Procureur, S. L.; Quaresma, M.; Quintans, C.; Rajotte, J.-F.; Ramos, S.; Rapatsky, V.; Reicherz, G.; Richter, A.; 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, K.; Schmitt, L.; 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.; Stolarski, M.; Sulc, M.; Sulej, R.; 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.; Windmolders, R.; Wiślicki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zhuravlev, N.; Zvyagin, A.
2013-01-01
We present a determination of the gluon polarisation Δg / g in the nucleon, based on the longitudinal double-spin asymmetry of DIS events with Q2 > 1 (GeV / c) 2 including a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam scattering off a polarised 6LiD target. The gluon polarisation is evaluated by a Neural Network approach for three intervals of the gluon momentum fraction xg covering the range 0.04
Gluon production in the Lipatov effective action formalism
NASA Astrophysics Data System (ADS)
Braun, M. A.; Pozdnyakov, S. S.; Salykin, M. Yu.; Vyazovsky, M. I.
2013-09-01
Gluon production on two scattering centers is studied in the formalism of reggeized gluons. Different contributions to the inclusive cross section are derived with the help of the Lipatov effective action. The AGK relations between these contributions are established. The inclusive cross section found is compared to the one in the dipole picture and demonstrated to be the same.
An approach to fast fits of the unintegrated gluon density
Knutsson, Albert; Bacchetta, Alessandro; Kutak, Krzyzstof; Jung, Hannes
2009-01-01
An approach to fast fits of the unintegrated gluon density has been developed and used to determine the unintegrated gluon density by fits to deep inelastic scatting di-jet data from HERA. The fitting method is based on the determination of the parameter dependence by help of interpolating between grid points in the parameter-observable space before the actual fit is performed.
NASA Astrophysics Data System (ADS)
Tsankov, Tsanko V.; Czarnetzki, Uwe
2016-08-01
A paper by El Saghir and Shannon (2012 Plasma Sources Sci. Technol. 21 025003) raises the question about the validity of the widely-used Druyvesteyn formula for obtaining the electron energy distribution function by cylindrical probes. They conclude that there are deviations between the Druyvesteyn formula for cylindrical and for spherical probes. In this comment this conclusion is questioned and the correct expressions are derived. It is shown that no such difference exists when all three velocity components are correctly accounted for. Furthermore, the disturbance to the plasma introduced by the probe is estimated.
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.
Gluon Polarisation in the Nucleon from High Transverse Momentum Hadron Pairs at COMPASS
Kurek, Krzysztof
2009-08-04
The main goal of the COMPASS spin physics programme is the measurement of the helicity contribution of the gluons, {delta}G/G, to the nucleon spin. It is determined from the longitudinal spin asymmetry in the scattering of 160 GeV polarised muons off a polarised LiD target. The new analysis and new COMPASS {delta}G/G result obtained from high transverse momentum hadron pairs for Q{sup 2}>1(GeV/c){sup 2} is presented. The weighted method based on a Neural Network approach is discussed. The result of {delta}G/G 0.08{+-}0.10(stat){+-}0.05(syst)disfavors a large positive contribution to the nucleon spin for a gluon momentum fraction around 0.08 and agrees with the previously obtained result from the analysis for the small Q{sup 2} kinematical region (Q{sup 2}<1(GeV/c){sup 2})
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.
Kawamura, E.; Verboncoeur, J.P.; Birdsall, C.K.
1996-12-31
The goal is to obtain the ion angular and energy distributions at the wafer of inductive and capacitive discharges. To do this on a standard uniform mesh with particle codes alone would be impractical because of the long time scale nature of the problem (i.e., 10{sup 6} time steps). A solution is to use a fluid code to simulate the bulk source region, while using a particle-in-cell code to simulate the sheath region. Induct95 is a 2d fluid code which can simulate inductive and capacitive discharges. Though it does not resolve the sheath region near the wafer, it provides diagnostics for the collisional bulk plasma (i.e., potentials, temperatures, fluxes, etc.). Also, fluid codes converge to equilibrium much faster than particle codes in collisional regimes PDP1 is a 1d3v particle-in-cell code which can simulate rf discharges. It can resolve the sheath region and obtain the ion angular and energy distributions at the wafer target. The overall running time is expected to be that of the fluid code.
NASA Astrophysics Data System (ADS)
Wetzel, Stephanie J.; Guttman, Charles M.; Girard, James E.
2004-11-01
The molecular mass distribution (MMD) obtained in synthetic polymer characterization by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) may be biased by preferential desorption/ionization of low mass polymer molecules, preferential ion attachment to larger polymers, or degradation and fragmentation due to the desorption process. In this study we focus on the effect of matrix and laser energy on the MMD of four synthetic polymers of low polydispersity with varying thermal stabilities. The four polymers considered were polystyrene (PS), poly(ethylene glycol) (PEG), poly(methyl methacrylate) (PMMA) and poly(tetrahydrofuran) (PTHF). The matrix in which the polymer is analyzed may also influence the laser energy effect of MALDI and was also considered in this paper. Three common matrixes were considered, dithranol, all trans-retinoic acid (RA) and 2,5-dihydroxybenzoic acid (DHB). Statistical analyses of the molecular mass distributions, obtained by varying laser energy and matrixes, reveal trends that can be used to describe the influences of matrix and laser energy on MALDI-TOF-MS data measurement of synthetic polymers. The statistical analysis revealed that the matrix has a greater effect on the polymer MMD than was expected. Polymers analyzed in DHB yielded lower mass moments than polymers analyzed in RA and dithranol. The effects of laser power on the MMD of the polymers were found to be matrix dependent.
Gluon-initiated production of a Kaluza-Klein gluon in a bulk Randall-Sundrum model
NASA Astrophysics Data System (ADS)
Allanach, Benjamin C.; Mahmoudi, Farvah; Skittrall, Jordan P.; Sridhar, K.
2010-03-01
In the Bulk Randall-Sundrum model, the Kaluza-Klein excitations of the gauge bosons are the primary signatures. In particular, the search for the Kaluza-Klein (KK) excitation of the gluon at hadron colliders is of great importance in testing this model. At the leading order in QCD, the production of this KK-gluon proceeds only via qbar q -initial states. We study the production of KK-gluons from gluon initial states at next-to-leading order in QCD. We find that, even after including the sub-dominant KK-gluon loops at this order, the next-to-leading order (NLO) cross-section is tiny compared to the leading order cross-section and unlikely to impact the searches for this resonance at hardon colliders.
Weak quark couplings induced by gluon corrections
NASA Astrophysics Data System (ADS)
Gavela, M. B.; Le Yaouanc, A.; Oliver, L.; Pène, O.; Raynal, J. C.
1980-12-01
We compute the quark couplings in flavor-changing semileptonic transitions induced by lowest-order gluon corrections. We investigate the consequences of these radiative corrections for the quark axial-vector coupling, the deviations from Cabibbo universality for the axial-vector relative to the vector current, and the induced couplings (first-class pseudoscalar and anomalous magnetic moment, and second-class scalar and pseudotensor). The correction lowers the axial-vector coupling and increases the magnetic moment. We study the dependence of the couplings on the quark mass difference. Some of these results, true to all orders in αs, generalize the theorem of Ademollo and Gatto. The effective current is pure V-A to a very good approximation for transitions of heavy quarks (m>~5 GeV).
Gluon Green functions free of quantum fluctuations
NASA Astrophysics Data System (ADS)
Athenodorou, A.; Boucaud, Ph.; De Soto, F.; Rodríguez-Quintero, J.; Zafeiropoulos, S.
2016-09-01
This letter reports on how the Wilson flow technique can efficaciously kill the short-distance quantum fluctuations of 2- and 3-gluon Green functions, remove the ΛQCD scale and destroy the transition from the confining non-perturbative to the asymptotically-free perturbative sector. After the Wilson flow, the behavior of the Green functions with momenta can be described in terms of the quasi-classical instanton background. The same behavior also occurs, before the Wilson flow, at low-momenta. This last result permits applications as, for instance, the detection of instanton phenomenological properties or a determination of the lattice spacing only from the gauge sector of the theory.
Bashir, A.; Gutierrez-Guerrero, L. X.; Tejeda-Yeomans, M. E
2008-07-02
There has been growing evidence that the infra-red enhancement of the form factors defining the quark-gluon vertex plays an important role both in dynamical chiral symmetry breaking and confinement, thus providing an intrinsic link between the the two inherently non-perturbative phenomena. Both lattice and Schwinger-Dyson equation studies 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 for large momenta where non-perturbative effects mellow down. In this article, we study this matching by carrying out a numerical analysis of the one loop result for the central Ball-Chiu form factor.
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.
Exclusive J/ψ and ϒ photoproduction and the low x gluon
NASA Astrophysics Data System (ADS)
Jones, S. P.; Martin, A. D.; Ryskin, M. G.; Teubner, T.
2016-04-01
We study exclusive vector meson photoproduction, γ p\\to V+p with V=J/\\psi or ϒ, at next-to-leading order (NLO) in collinear factorisation, in order to examine what may be learnt about the gluon distribution at very low x. We examine the factorisation scale dependence of the predictions. We argue that, using knowledge of the NLO corrections, terms enhanced by a large {ln}(1/ξ ) can be reabsorbed in the LO part by a choice of the factorisation scale. (In these exclusive processes ξ takes the role of Bjorken-x.) Then, the scale dependence coming from the remaining NLO contributions has no {ln}(1/ξ ) enhancements. As a result, we find that predictions for the amplitude of ϒ production are stable to within about ±15%. This will allow data for the exclusive process {pp}\\to p{{\\Upsilon }}p at the Large Hadron Collider (LHC), particularly from LHCb, to be included in global parton analyses to constrain the gluon parton distribution function (PDF) down to x∼ {10}-5. Moreover, the study of exclusive J/\\psi photoproduction indicates that the gluon density found in the recent global PDF analyses is too small at low x and low scales.
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.
Properties of Non-Conformal Quark Gluon Plasma of Holographic QCD Models from Compactified D4 Branes
NASA Astrophysics Data System (ADS)
Naji, J.
2016-08-01
In this article, we obtain some thermodynamics quantities of non-conformal gluonic matter. We extract specific heat, enthalpy and equation of state in terms of the temperature. Using transport properties we find important quantities of corresponding quark gluon plasma like drag force and jet-quenching.
Properties of Non-Conformal Quark Gluon Plasma of Holographic QCD Models from Compactified D4 Branes
NASA Astrophysics Data System (ADS)
Naji, J.
2016-03-01
In this article, we obtain some thermodynamics quantities of non-conformal gluonic matter. We extract specific heat, enthalpy and equation of state in terms of the temperature. Using transport properties we find important quantities of corresponding quark gluon plasma like drag force and jet-quenching.
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.
NASA Astrophysics Data System (ADS)
Domènech, Guillem; Mavrouli, Olga; Corominas, Jordi; Abellán, Antonio; Merchel, Silke; Pavetich, Stefan; Rugel, Georg
2015-04-01
Magnitude-cumulative frequency (MCF) relations are commonly used components for assessing the rockfall hazard using databases of recorded events. However, in some cases, data are lacking or incomplete. To overcome this restriction, the volume distribution of the rockfall scars has been used instead. The latter may yield the temporal probability of occurrence if the time span required to generate the scars is known. The Montsec range, located in the Eastern Pyrenees, Spain, was chosen as a pilot study area for investigating MCF distributions. This cliff, which is composed of limestones from Upper Cretaceous age, shows distinct evidences of rockfall activity, including large recent rockfall scars. These areas are identifiable by their orange colour, which contrasts in front of the greyish old stable (reference) surface of the cliff face. We present a procedure to obtain the MCF of the rockfall scars by dating an old reference cliff surface and measuring the total volume released since then. The reference cliff surface was dated using the terrestrial cosmogenic nuclide (TCN) chlorine-36 (Merchel et al., 2013). We used the Rockfall Scar Size Distribution (RSSD) obtained in Domènech et al. (2014) that considers several rockfall pattern scenarios. Scenario 1 allows for, mostly, large rockfall scar volumes, scenario 2 considers smaller occurrences and scenario 3 suggests that rockfall scars can be the result of one or several rockfall events, and thus contemplating a wider range of scar volumes. The main steps of the methodology are: a) Obtaining the RSSD, b) Volume calculation of material lost, c) Calculation of time (T0) elapsed for the cliff to retreat (age of the old reference surface), and d) generation of the MCF curve from the RSSD. A total volume of material lost of 78900 m3 was obtained as well as an elapsed period of time of 15350 years. The MCF curves for different rockfall scenarios are found to be well fitted by a power law with exponents -1.7, -1.1 and -1
Proper definition and evolution of generalized transverse momentum dependent distributions
NASA Astrophysics Data System (ADS)
Echevarria, Miguel G.; Idilbi, Ahmad; Kanazawa, Koichi; Lorcé, Cédric; Metz, Andreas; Pasquini, Barbara; Schlegel, Marc
2016-08-01
We consider one of the most fundamental sets of hadronic matrix elements, namely the generalized transverse momentum dependent distributions (GTMDs), and argue that their existing definitions lack proper evolution properties. By exploiting the similarity of GTMDs with the much better understood transverse momentum distributions, we argue that the existing definitions of GTMDs have to include an additional dependence on soft gluon radiation in order to render them properly defined. With this, we manage to obtain the evolution kernel of all (un)polarized quark and gluon GTMDs, which turns out to be spin independent. As a byproduct, all large logarithms can be resummed up to next-to-next-to-leading-logarithmic accuracy with the currently known perturbative ingredients.
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.
Chromohydrodynamic approach to the unstable quark-gluon plasma
NASA Astrophysics Data System (ADS)
Manuel, Cristina; Mrówczyński, Stanisław
2006-11-01
We derive hydrodynamic-like equations that are applicable to short-time-scale color phenomena in the quark-gluon plasma. The equations are solved in the linear response approximation, and the gluon polarization tensor is derived. As an application, we study the collective modes in a two-stream system and find plasma instabilities when the fluid velocity is larger than the speed of sound in the plasma. The chromohydrodynamic approach, discussed here in detail, should be considered as simpler over other approaches and well-designed for numerical studies of the dynamics of an unstable quark-gluon plasma.
NASA Astrophysics Data System (ADS)
Williamson, Nathan H.; Röding, Magnus; Galvosas, Petrik; Miklavcic, Stanley J.; Nydén, Magnus
2016-08-01
We present the pseudo 2-D relaxation model (P2DRM), a method to estimate multidimensional probability distributions of material parameters from independent 1-D measurements. We illustrate its use on 1-D T1 and T2 relaxation measurements of saturated rock and evaluate it on both simulated and experimental T1-T2 correlation measurement data sets. Results were in excellent agreement with the actual, known 2-D distribution in the case of the simulated data set. In both the simulated and experimental case, the functional relationships between T1 and T2 were in good agreement with the T1-T2 correlation maps from the 2-D inverse Laplace transform of the full 2-D data sets. When a 1-D CPMG experiment is combined with a rapid T1 measurement, the P2DRM provides a double-shot method for obtaining a T1-T2 relationship, with significantly decreased experimental time in comparison to the full T1-T2 correlation measurement.
Williamson, Nathan H; Röding, Magnus; Galvosas, Petrik; Miklavcic, Stanley J; Nydén, Magnus
2016-08-01
We present the pseudo 2-D relaxation model (P2DRM), a method to estimate multidimensional probability distributions of material parameters from independent 1-D measurements. We illustrate its use on 1-D T1 and T2 relaxation measurements of saturated rock and evaluate it on both simulated and experimental T1-T2 correlation measurement data sets. Results were in excellent agreement with the actual, known 2-D distribution in the case of the simulated data set. In both the simulated and experimental case, the functional relationships between T1 and T2 were in good agreement with the T1-T2 correlation maps from the 2-D inverse Laplace transform of the full 2-D data sets. When a 1-D CPMG experiment is combined with a rapid T1 measurement, the P2DRM provides a double-shot method for obtaining a T1-T2 relationship, with significantly decreased experimental time in comparison to the full T1-T2 correlation measurement. PMID:27344611
Numerical Study of the Ghost-Ghost-Gluon Vertex on the Lattice
Mihara, A.; Cucchieri, A.; Mendes, T.
2004-12-02
It is well known that, in Landau gauge, the renormalization function of the ghost-ghost-gluon vertex Z-tilde1 (p2) is finite and constant, at least to all orders of perturbation theory. On the other hand, a direct non-perturbative verification of this result using numerical simulations of lattice QCD is still missing. Here we present a preliminary numerical study of the ghost-ghost-gluon vertex and of its corresponding renormalization function using Monte Carlo simulations in SU(2) lattice Landau gauge. Data were obtained in 4 dimensions for lattice couplings {beta} = 2.2, 2.3, 2.4 and lattice sides N = 4, 8, 16.
Comment on ``Damping of energetic gluons and quarks in high-temperature QCD''
NASA Astrophysics Data System (ADS)
Rebhan, Anton
1992-07-01
Burgess and Marini have recently pointed out that the leading contribution to the damping rate of energetic gluons and quarks in the QCD plasma, given by γ=cg2ln(1/g)T, can be obtained by simple arguments obviating the need of a fully resummed perturbation theory as developed by Braaten and Pisarski. Their calculation confirmed previous results of Braaten and Pisarski, but contradicted those proposed by Lebedev and Smilga. While agreeing with the general considerations made by Burgess and Marini, I correct their actual calculation of the damping rates, which is based on a wrong expression for the static limit of the resummed gluon propagator. The effect of this, however, turns out to be canceled fortuitously by another mistake, so as to leave all of their conclusions unchanged. I also verify the gauge independence of the results, which in the corrected calculation arises in a less obvious manner.
Comment on Damping of energetic gluons and quarks in high-temperature QCD''
Rebhan, A. )
1992-07-01
Burgess and Marini have recently pointed out that the leading contribution to the damping rate of energetic gluons and quarks in the QCD plasma, given by {gamma}={ital cg}{sup 2}ln(1/{ital g}){ital T}, can be obtained by simple arguments obviating the need of a fully resummed perturbation theory as developed by Braaten and Pisarski. Their calculation confirmed previous results of Braaten and Pisarski, but contradicted those proposed by Lebedev and Smilga. While agreeing with the general considerations made by Burgess and Marini, I correct their actual calculation of the damping rates, which is based on a wrong expression for the static limit of the resummed gluon propagator. The effect of this, however, turns out to be canceled fortuitously by another mistake, so as to leave all of their conclusions unchanged. I also verify the gauge independence of the results, which in the corrected calculation arises in a less obvious manner.
Chiral vortical wave and induced flavor charge transport in a rotating quark-gluon plasma
NASA Astrophysics Data System (ADS)
Jiang, Yin; Huang, Xu-Guang; Liao, Jinfeng
2015-10-01
We show the existence of a new gapless collective excitation in a rotating fluid system with chiral fermions, named the chiral vortical wave (CVW). The CVW has its microscopic origin at the quantum anomaly and macroscopically arises from interplay between vector and axial charge fluctuations induced by vortical effects. The wave equation is obtained both from hydrodynamic current equations and from chiral kinetic theory, and its solutions show nontrivial CVW-induced charge transport from different initial conditions. Using the rotating quark-gluon plasma in heavy ion collisions as a concrete example, we show the formation of an induced flavor quadrupole in quark-gluon plasma and estimate the elliptic flow splitting effect for Λ baryons that may be experimentally measured.
The Boltzmann equation for gluons at early times after a heavy ion collision
NASA Astrophysics Data System (ADS)
Mueller, A. H.
2000-03-01
A Boltzmann equation is given for the early stages of evolution of the gluon system produced in a head-on heavy ion collision. The collision term is taken from gluon-gluon scattering in the one-gluon approximation.
and
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
LUCERO, DANIEL A; PERKINS, W GEORGE
1999-08-26
The US 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, New Mexico. Performance assessment analyses indicate that human intrusions by inadvertent, intermittent drilling for resources provide the only credible mechanisms for releases of radionuclides from the disposal system. In modeling long-term brine releases, subsequent to a drilling event, potential migration pathways through the permeable layers of rock above the Salado formation were analyzed. 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 earned 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 {sup 241}Pu and {sup 241}Am 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 {sup 22}Na. Elution experiments carried out over periods of a few days with tracers {sup 232}U and {sup 239}Np indicated that these tracers were weakly retarded as indicated by delayed elution of the species. Elution experiments with tracers {sup 241}Pu and {sup 241}Am 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 {sup 241}Pu and {sup 241}Am
Bayle, Kevin; Gilbert, Alexis; Julien, Maxime; Yamada, Keita; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Yoshida, Naohiro; Remaud, Gérald S
2014-10-10
Intramolecular (13)C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic (13)C NMR spectrometry provides a general tool for measuring the position-specific (13)C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal (13)C distribution, and (ii) an approach to determining the "absolute" position-specific (13)C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the (13)C frequency range of the studied molecule, i.e. the chemical shift range. The "absolute value" and, therefore, the trueness of the (13)C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH3 by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py-irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py-irm-MS (thus, the "true" value) while the other showed a bias, which was dependent to the range covered by the resonance frequencies of the molecule. Therefore, the former can be used directly for studying isotope affiliations, while the latter can only be used directly for comparative data, for example in authenticity studies, but can also be used to obtain the true values by applying appropriate correction factors. The present study assesses several key protocol
Kertesz, Vilmos; Van Berkel, Gary J; Vavek, Marissa; Koeplinger, Kenneth A.; Schneider, Bradley B; Covey, Thomas R.
2008-01-01
Desorption electrospray ionization tandem mass spectrometry (DESI-MS/MS) and whole-body autoradiography (WBA) were used for chemical imaging of whole-body thin tissue sections of mice intravenously dosed with propranolol (7.5 mg/kg). DESI-MS/MS imaging utilized selected reaction monitoring detection performed on an AB/MDS SCIEX 4000 QTRAP mass spectrometer equipped with a prototype extended length particle discriminator interface. Propranolol images of the tissue sections using DESI-MS/MS were obtained at surface scan rates of 0.1, 0.5, 2 and 7 mm/s. Although signal decreased with increasing scan rate, useful whole-body images for propranolol were obtained from the tissues even at 7 mm/s, which required just 79 min of analysis time. Attempts to detect and image the distribution of the known propranolol metabolites were unsuccessful. Regions of the tissue sections showing the most radioactivity from WBA sections were excised and analyzed by HPLC with radiochemical detection to determine relative levels of propranolol and metabolites present. Comparison of the DESI-MS/MS signal for propranolol and the radioactivity attributed to propranolol from WBA sections indicated nominal agreement between the two techniques for the amount of propranolol in the brain, lung, and liver. Data from the kidney showed an unexplained disparity between the two techniques. The results of this study show the feasibility of using DESI-MS/MS to obtain useful chemical images of a drug in whole-body thin tissue sections following drug administration at a pharmacologically relevant level. Further optimization to improve sensitivity and enable detection of the drug metabolites will be among the requirements necessary to move DESI-MS/MS chemical imaging forward as a practical tool in drug discovery.
JETS and QCD: a historical review of the discovery of the quark and gluon jets and its impact on QCD
NASA Astrophysics Data System (ADS)
Ali, A.; Kramer, G.
2011-04-01
The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review, which is primarily a description of the discovery of the quark and gluon jets and the impact of their observation on Quantum Chromodynamics, we elaborate, in particular, the role of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e+e- collisions will be in the foreground of the discussion and we will concentrate on the theory that was contemporary with the relevant experiments at the electron-positron colliders. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/pbar{p} collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W ± , Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics.
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.
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.
Veneziano ghost, modified gluon propagator, and gauge copies in QCD
NASA Astrophysics Data System (ADS)
Dudal, D.; Guimaraes, M. S.
2016-04-01
In this short note, we come back to the recent proposal put forward by Kharzeev and Levin [Phys. Rev. Lett. 114, 242001 (2015)], in which they phenomenologically couple the nonperturbative Veneziano ghost to the perturbative gluon, leading to a modified gluon propagator (the "glost") of the Gribov type, with complex poles. As such, a possible link was made between the QCD topological θ -vacuum (Veneziano ghost) and color confinement (no physically observable gluons). We discuss some subtleties concerning gauge (Becchi-Rouet-Stora-Tuytin) invariance of this proposal, related to the choice of Feynman gauge. We draw particular attention to the incompatibility in the longitudinal sector with available nonperturbative results for the linear covariant gauge. We furthermore provide an example in the Landau gauge of a similar phenomenological vertex that also describes the necessary Veneziano ghost but does not affect the Landau gauge gluon propagator.
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.
Physics of the gluon-helicity contribution to proton spin.
Ji, Xiangdong; Zhang, Jian-Hui; Zhao, Yong
2013-09-13
The total gluon helicity in a polarized proton, measurable in high-energy scattering, is shown to be the large momentum limit of a gauge-invariant but nonlocal, frame-dependent gluon spin E × A⊥ in QCD. This opens a door for a nonperturbative calculation of this quantity in lattice QCD and also justifies using free-field expressions in the light-cone gauge as physical observables. PMID:24074075
Colored plasmons in a quark-gluon plasma near equilibrium
NASA Astrophysics Data System (ADS)
Hein, Ulrich; Siemens, Philip J.
1985-08-01
Within a kinetic theory for QCD plasmas we study the color response function near thermodynamic equilibrium. Its poles yield a longitudinal and a transverse collective mode, both starting at the plasma frequency. Due to the gluon contribution there is no Landau damping for these modes, and creation of gluon or q- overlinep pairs is the dominant damping mechanism. In an electron plasma the generally quoted Landau damping near threshold is shown to be an artifact of the non-relativistic approximation.
NASA Astrophysics Data System (ADS)
Beucher, R.; Brown, R. W.
2013-12-01
individual samples temperature offset requirements. The geothermal gradient can be either treated as a parameter in the inversion scheme or evaluated when local vertical profile or heat flow measurements are available. As data for each sample is inverted several times with different subsets, or as a member of different families, we then extract the subset with the lowest misfit and assign that sample to its respective ''family'' whose optimum time-temperature path is subsequently assigned to the sample. We thus obtain a set of thermal histories (one for each sample) which can then be interpolated to obtain exhumation rates or maximum temperature maps. We demonstrate our approach on a variety of synthetic datasets, generated for different geomorphologies and sampling densities, using the 3D thermal Pecube code in order to test the resolution and limits of the method. The approach is then applied to a 600 by 600 km area in northern Namibia where an extensive apatite fission track dataset including ages and track length distributions is available. We finally discuss extension of the technique to multiple thermochronometers. We also discuss possible future modifications and strategies for improving the flexibility and computational efficiency and effectiveness of the method.
Voicu, Victor; Sora, Iuliana; Sârbu, Costel; David, Victor; Medvedovici, Andrei
2010-08-01
Chromatographic retention data obtained from interactions between some oxime-type compounds and different stationary phases (involving hydrophobic interaction, ion pairing formation availability, pi-pi, H-bonding, dipole-dipole, ion-dipole, electrostatic interaction and glycoprotein binding ability) have been studied. The logarithms of the capacity factors extrapolated at 0% or 100% organic solvent, resulting from the functional dependencies between retention and mobile phase composition, were used for estimation of different kind of hydrophobicity or hydrophilicity descriptors (HHDs) of these compounds. The conditions of the chromatographic separation were chosen as close as possible to in-vivo conditions (the aqueous component of the mobile phase has a pH in the physiologic interval 6.8-7.2, 0.9% sodium chloride was added to reproduce ionic strength and isotonic character, and the temperature was set at 37 degrees C). These descriptors characterizing the partition between stationary/mobile phases through specific interactions may be directly used for correlation to biological distribution processes, such as penetration of the blood/brain barrier. Oxime-type compounds used as acetylcholinesterase (AChE, E.C.3.1.1.7) reactivators have been considered for the retention study. The choice is supported by their use in the therapy of acute intoxication with organophosphorus AChE inhibitors (OPIs, especially nerve agents and pesticides), a rather complicated chemistry in solution and a relative lack of data about computational molecular descriptors used for modeling biological partition/distribution. Some correlations between the determined descriptors and computational values have also been discussed. PMID:20202777
Energy loss in unstable quark-gluon plasma
NASA Astrophysics Data System (ADS)
Carrington, Margaret E.; Deja, Katarzyna; Mrówczyński, Stanisław
2015-10-01
The momentum distribution of quark-gluon plasma at the early stage of a relativistic heavy-ion collision is anisotropic; consequently, the system, which is assumed to be weakly coupled, is unstable owing to chromomagnetic plasma modes. We consider a high-energy parton which flies across such an unstable plasma, and the energy transfer between the parton and the medium is studied as an initial value problem. In the case of equilibrium plasmas, the well-known formula of collisional energy loss is reproduced. The unstable plasma case is much more complex, and the parton can lose or gain energy depending on the initial conditions. The extremely prolate and extremely oblate systems are considered as examples of unstable plasmas, and two classes of initial conditions are discussed. When the initial chromodynamic field is uncorrelated with the color state of the parton, it typically looses energy, and the magnitude of the energy loss is comparable to that in an equilibrium plasma of the same density. When the initial chromodynamic field is induced by the parton, it can be either accelerated or decelerated depending on the relative phase factor. With a correlated initial condition, the energy transfer grows exponentially in time and its magnitude can much exceed the absolute value of energy loss in an equilibrium plasma. The energy transfer is also strongly directionally dependent. Consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.
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. PMID:18969975
NASA Astrophysics Data System (ADS)
Usowicz, B.; Marczewski, W.; Lipiec, J.; Usowicz, J. B.; Sokolowska, Z.; Dabkowska-Naskret, H.; Hajnos, M.; Lukowski, M. I.
2009-04-01
The purpose is obtaining trustful ground based measurement data of SM (Soil Moisture) for validating SMOS, respectively to spatial and temporal distribution and variations. A use of Time Domain Reflectometric (TDR) method is fast, simple and less destructive, to the soil matter, than a usual standard gravimetric method. TDR tools operate efficiently, enable nearly instant measurements, and allow on collecting many measurements from numerous sites, even when operated manually in short time intervals. The method enables also very frequent sampling of SM at few selected fixed sites, when long terms of temporal variations are needed. In effect one obtains reasonably large data base for determining spatial and temporal distributions of SM. The study is devoted to determining a plan on collecting TDR data, in the scales of small and large field areas, and checking their relevance to those available from gravimetric methods. Finally, the ground based SM distributions are needed for validating other SM distributions, available remotely in larger scales, from the satellite data of ENVISAT-ASAR, and from SMOS (Soil Moisture and Ocean Salinity Mission) when it becomes operational. The ground based evaluations are served mainly by geo-statistical analysis. The space borne estimations are retrieved by image processing and physical models, proper to relevant Remote Sensing (RS) instruments on the orbit. Finally, validation must engage again the geo-statistical evaluations, to assess the agreement between direct and remote sensing means, and provide a measure of trust for extending the limited scales of the ground based data, on concluding the agreement in scales proper to the satellite data. The study is focused mainly on trustful evaluating data from the ground, provided independently on satellite data sources. SM ground based data are collected permanently at 2 selected tests sites, and temporary in areas around the tests sites, in one day sessions, repeated several times per
NASA Astrophysics Data System (ADS)
Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju
2012-09-01
The event-by-event multiplicity distribution, the energy densities and energy density weighted eccentricity moments ɛn (up to n=6) at early times in heavy-ion collisions at both the BNL Relativistic Heavy Ion Collider (RHIC) (s=200GeV) and the CERN Large Hardron Collider (LHC) (s=2.76TeV) are computed in the IP-Glasma model. This framework combines the impact parameter dependent saturation model (IP-Sat) for nucleon parton distributions (constrained by HERA deeply inelastic scattering data) with an event-by-event classical Yang-Mills description of early-time gluon fields in heavy-ion collisions. The model produces multiplicity distributions that are convolutions of negative binomial distributions without further assumptions or parameters. In the limit of large dense systems, the n-particle gluon distribution predicted by the Glasma-flux tube model is demonstrated to be nonperturbatively robust. In the general case, the effect of additional geometrical fluctuations is quantified. The eccentricity moments are compared to the MC-KLN model; a noteworthy feature is that fluctuation dominated odd moments are consistently larger than in the MC-KLN model.
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.
Nuclear modification factor in an anisotropic quark-gluon plasma
NASA Astrophysics Data System (ADS)
Mandal, Mahatsab; Bhattacharya, Lusaka; Roy, Pradip
2011-10-01
We calculate the nuclear modification factor (RAA) of light hadrons by taking into account the initial state momentum anisotropy of the quark-gluon plasma (QGP) expected to be formed in relativistic heavy ion collisions. Such an anisotropy can result from the initial rapid longitudinal expansion of the matter. A phenomenological model for the space-time evolution of the anisotropic QGP is used to obtain the time dependence of the anisotropy parameter ξ and the hard momentum scale, phard. The result is then compared with the PHENIX experimental data to constrain the isotropization time scale, τiso for fixed initial conditions (FIC). It is shown that the extracted value of τiso lies in the range 0.5⩽τiso⩽1.5. However, using a fixed final multiplicity (FFM) condition does not lead to any firm conclusion about the extraction of the isotropization time. The present calculation is also extended to contrast with the recent measurement of nuclear modification factor by the ALICE collaboration at s=2.76 TeV. It is argued that in the present approach, the extraction of τiso at this energy is uncertain and, therefore, refinement of the model is necessary. The sensitivity of the results on the initial conditions has been discussed. We also present the nuclear modification factor at Large Hadron Collider (LHC) energies with s=5.5 TeV.
Dual QCD thermodynamics and quark-gluon plasma
NASA Astrophysics Data System (ADS)
Chandola, H. C.; Punetha, Garima; Dehnen, H.
2016-01-01
Using grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of dual QCD based on magnetic symmetry has been presented and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD based bag construction has been shown to lead to the radial pressure on bag surface in terms of the vector glueball masses of magnetically condensed QCD vacuum. Constructing the grand canonical partition function, the energy density and plasma pressure have been derived and used to compute the critical temperatures for QGP-hadron phase transition along with its dynamics. A comparison of the values of critical temperatures for QGP-hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to either the relaxation of the system via a mixed phase of QGP and hot hadron gas or go through a crossover. The associated profiles of the normalized energy density and specific heat have been shown to lead to a large latent heat generation and indicate the onset of a first-order QGP phase transition which turns into a rapid crossover for the case of temperature dependent bag parameter. The squared speed of sound has been shown to act as a physical measure of large thermodynamical fluctuations near transition point. The possible implications of trace anomaly and conformal measure on QGP formation have also been discussed.
Heavy-Quarkonium Potential from Lattice Gluon Propagator
NASA Astrophysics Data System (ADS)
Serenone, W. M.; Cucchieri, A.; Mendes, T.
2016-04-01
The study of heavy quarks is of great interest for the search of physics beyond the Standard Model and the understanding of nonperturbative aspects of QCD. One of the early attempts to study these systems was the potential model approach. The Cornell potential is perhaps the most successful of these potentials. However, the use of perturbation theory in its building process implies that it is unable to model confinement without the ad-hoc addition of a linear term. In this paper, we modify the Cornell potential by using a (nonperturbative) lattice gluon propagator. This approach allowed us to verify that the use of perturbation theory washes away confinement. We were able to use this modified potential in the Schrödinger equation to obtain numerically the spectrum of heavy quarkonia (charmonium and bottomonium). We use the Cornell-potential spectrum as a benchmark of our potential. The result shows that our potential was able to describe better the spin-average of the experimental states than the Cornell potential. We also computed interquark distances for the quarkonia states.
Inclusive two-gluon and valence-quark-gluon production in DIS and pA collisions
Jalilian-Marian, Jamal; Kovchegov, Yuri V.
2004-12-01
We calculate production cross sections of a forward quark-gluon pair and of two gluons at midrapidity in deep inelastic scattering and in high energy proton-nucleus collisions. The calculation is performed in the framework of the color glass condensate formalism. We first calculate the cross sections in the quasiclassical approximation, which includes multiple rescatterings in the target. We then proceed to include the effects of nonlinear small-x evolution in the production cross sections. It is interesting to note that our result for the two-gluon production cross section appears to be in direct violation of Abramovsky-Gribov-Kanchelli cutting rules, which is the first example of such violation in QCD. The calculated quark-gluon and gluon-gluon production cross sections can be used to construct theoretical predictions for two-particle azimuthal correlations at the Relativistic Heavy Ion Collider and LHC (I{sup p(d)A}) as well as for deep inelastic scattering experiments at the Hadron Electron Ring Accelerator and the Electron-Relativistic Heavy Ion Collider.
Higher-Twist Mechanism and Inclusive Gluon Production in Pion-Proton Collisions
NASA Astrophysics Data System (ADS)
Ahmadov, A. I.; Aydin, C.; Myrzakulov, R.; Uzun, O.
2016-01-01
We calculate the contribution of the higher-twist Feynman diagrams to the large-pT inclusive gluon production cross section in πp collisions incase of the running coupling and frozen coupling approaches within perturbative and holographic QCD. The structure of infrared renormalon singularities of the higher-twist subprocess cross section are obtained and the resummed higher-twist cross sections (Borel sum) with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section are compared and analyzed.
Higher-twist mechanism and inclusive gluon production in pion-proton collisions
NASA Astrophysics Data System (ADS)
Ahmadov, A. I.; Aydin, C.; Myrzakulov, R.; Uzun, O.
2015-12-01
We calculate the contribution of the higher-twist Feynman diagrams to the large-pT inclusive gluon production cross-section in πp collisions in case of the running coupling and frozen coupling approaches within perturbative and holographic QCD. The structure of infrared renormalon singularities of the higher-twist subprocess cross-section is obtained and the resummed higher-twist cross-sections (Borel sum) with the ones obtained in the framework of the frozen coupling approach and leading-twist cross-section are compared and analyzed.
NASA Astrophysics Data System (ADS)
Harlander, Robert V.; Liebler, Stefan; Mantler, Hendrik
2013-06-01
This article describes the code SusHi (for "Supersymmetric Higgs") [108] which calculates the cross sections pp/pp ¯ →ϕ+X in gluon fusion and bottom-quark annihilation in the SM and the MSSM, where ϕ is any of the neutral Higgs bosons within these models. Apart from inclusive cross sections up to NNLO QCD, differential cross sections with respect to the Higgs transverse momentum pT and (pseudo-)rapidity y(η) can be calculated through NLO QCD. In the case of gluon fusion, SusHi contains NLO QCD contributions from the third family of quarks and squarks, NNLO corrections due to top-quarks, approximate NNLO corrections due to top-squarks, and electro-weak effects. It supports various renormalization schemes for the sbottom sector and the bottom Yukawa coupling, as well as resummation effects of higher order tanβ-enhanced sbottom contributions. SusHi provides a link to FeynHiggs for the calculation of the Higgs masses. Program SummaryProgram title: SusHi Catalogue identifier: AEOY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 47725 No. of bytes in distributed program, including test data, etc.: 338380 Distribution format: tar.gz Programming language: Fortran 77. Computer: Personal computer. Operating system: Unix/Linux, Mac OS. RAM: A few 100 MB Classification: 11.1. External routines: LHAPDF (http://lhapdf.hepforge.org), FeynHiggs (http://www.feynhiggs.de) Nature of problem: Calculation of inclusive and exclusive Higgs production cross sections in gluon fusion and bottom-quark annihilation in the Standard Model and the MSSM through next-to-leading order QCD, includes next-to-next-to-leading order top-(s)quark contributions and electro-weak effects Solution method: Numerical Monte Carlo integration
Gaining (mutual) information about quark/gluon discrimination
NASA Astrophysics Data System (ADS)
Larkoski, Andrew J.; Thaler, Jesse; Waalewijn, Wouter J.
2014-11-01
Discriminating quark jets from gluon jets is an important but challenging problem in jet substructure. In this paper, we use the concept of mutual information to illuminate the physics of quark/gluon tagging. Ideal quark/gluon separation requires only one bit of truth information, so even if two discriminant variables are largely uncorrelated, they can still share the same "truth overlap". Mutual information can be used to diagnose such situations, and thus determine which discriminant variables are redundant and which can be combined to improve performance. Using both parton showers and analytic resummation, we study a two-parameter family of generalized angularities, which includes familiar infrared and collinear (IRC) safe observables like thrust and broadening, as well as IRC unsafe variants like p {/T D } and hadron multiplicity. At leading-logarithmic (LL) order, the bulk of these variables exhibit Casimir scaling, such that their truth overlap is a universal function of the color factor ratio C A /C F . Only at next-to-leading-logarithmic (NLL) order can one see a difference in quark/gluon performance. For the IRC safe angularities, we show that the quark/gluon performance can be improved by combining angularities with complementary angular exponents. Interestingly, LL order, NLL order, Pythia 8, and Herwig++ all exhibit similar correlations between observables, but there are significant differences in the predicted quark/gluon discrimination power. For the IRC unsafe angularities, we show that the mutual information can be calculated analytically with the help of a nonperturbative "weighted-energy function", providing evidence for the complementarity of safe and unsafe observables for quark/gluon discrimination.
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).
Collective Flow signals the Quark Gluon Plasma
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.
2004-12-02
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{center_dot}GeV: here the hydrodynamic model has predicted the collapse of the v1-flow and of the v2-flow at {approx} 10 A{center_dot}GeV; at 40 A{center_dot}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 potential evidence for a first order phase transition at high baryon density {rho}B. 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 {mu}B {approx_equal} 400 MeV (y {approx_equal} 4 - 5), where the collapse of the proton flow should be seen in analogy to the 40 A{center_dot}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 (QGP)
Nahon, Laurent; Garcia, Gustavo A.; Soldi-Lose, Heloiese; Daly, Steven; Powis, Ivan
2010-09-15
As an intermediate state of matter between the free monomeric gas phase and the solid state, clusters may exhibit a specific electronic structure and photoionization dynamics that can be unraveled by different types of electron spectroscopies. From mass-selected ion yield scans measured for photoionization of (R)-camphor, the ionization potentials (IPs) of the monomer (8.66{+-}0.01 eV), and of the homochiral dimer ({<=}8.37{+-}0.01 eV) and trimer ({<=}8.30{+-}0.01 eV) were obtained. These spectra, combined with threshold photoelectron spectroscopy and velocity map ion imaging, allow us to show that the camphor monomer and dimer photoionization channels are decoupled, i.e., that the highest occupied molecular orbital (HOMO) of the dimer does not undergo a dissociative ionization process that would lead to a spurious contribution to the monomer ion channel. Therefore mass selection, as achieved in our imaging photoelectron-photoion coincidence experiments, leads to size selection of the nascent monomer or dimer species. Since both the monomer and dimer are chiral, their photoelectron angular distribution (PAD) not only involves the usual {beta} anisotropy parameter but also a chiral asymmetry parameter b{sub 1} that can generate a forward-backward asymmetry in the PAD. This has been investigated using circularly polarized light (CPL) to record the photoelectron circular dichroism (PECD) in the near-threshold vacuum-ultraviolet (VUV) photoionization region. Analysis of size-selected electron images recorded with left- and right-handed CPL shows that over the first 1.5 eV above the HOMO orbital ionization potentials (IPs), the {beta} parameter is not affected by the dimerization process, while the chiral b{sub 1} parameter shows clear differences between the monomer and the dimer, confirming that PECD is a subtle long-range probe of the molecular potential.
NASA Astrophysics Data System (ADS)
Sumlin, B.; Arnott, W. P.; Moosmuller, H.
2012-12-01
The MODIS instruments aboard the Aqua and Terra satellites provide aerosol optical depth information for the entire Earth on a daily basis. Ideally, satellite measurements should correlate with ground-based measurements in order to be useful for air quality applications. Reno, Nevada, USA is a high desert city situated in the Great Basin. Its unique geography and proximity to urban and biomass burning aerosol sources make it an ideal candidate for aerosol research. In August 2011, the Reno Aerosol Characterization Experiment measured atmospheric aerosols with a ground-based Cimel CE-318 sun-photometer and in situ photoacoustic instrumentation to quantify aerosol concentrations at the surface and in the column. However, the results of these measurements indicated the existence of a more complex system of aerosol mixing above the atmospheric boundary layer than previously thought. In order to validate these measurements, an autonomous suite of instrumentation has been developed. This device is carried aloft by a weather balloon and utilizes a reciprocal nephelometer to obtain a high-resolution profile of the vertical distribution of aerosol light scattering coefficient, as well as instrumentation to record atmospheric variables such as temperature, pressure, relative humidity, and dew point. Position, course, speed, and altitude are logged with an onboard GPS module and correlated with atmospheric and aerosol measurements. Presented is the design and development of this new instrument, its comparison with proven laboratory instruments, data gathered from flights during August-November 2012, and its comparison to ground-based measurements and satellite data from the MODIS instruments.
NASA Astrophysics Data System (ADS)
Nahon, Laurent; Garcia, Gustavo A.; Soldi-Lose, Héloïse; Daly, Steven; Powis, Ivan
2010-09-01
As an intermediate state of matter between the free monomeric gas phase and the solid state, clusters may exhibit a specific electronic structure and photoionization dynamics that can be unraveled by different types of electron spectroscopies. From mass-selected ion yield scans measured for photoionization of (R)-camphor, the ionization potentials (IPs) of the monomer (8.66±0.01 eV), and of the homochiral dimer (⩽8.37±0.01 eV) and trimer (⩽8.30±0.01 eV) were obtained. These spectra, combined with threshold photoelectron spectroscopy and velocity map ion imaging, allow us to show that the camphor monomer and dimer photoionization channels are decoupled, i.e., that the highest occupied molecular orbital (HOMO) of the dimer does not undergo a dissociative ionization process that would lead to a spurious contribution to the monomer ion channel. Therefore mass selection, as achieved in our imaging photoelectron-photoion coincidence experiments, leads to size selection of the nascent monomer or dimer species. Since both the monomer and dimer are chiral, their photoelectron angular distribution (PAD) not only involves the usual β anisotropy parameter but also a chiral asymmetry parameter b1 that can generate a forward-backward asymmetry in the PAD. This has been investigated using circularly polarized light (CPL) to record the photoelectron circular dichroism (PECD) in the near-threshold vacuum-ultraviolet (VUV) photoionization region. Analysis of size-selected electron images recorded with left- and right-handed CPL shows that over the first 1.5 eV above the HOMO orbital ionization potentials (IPs), the β parameter is not affected by the dimerization process, while the chiral b1 parameter shows clear differences between the monomer and the dimer, confirming that PECD is a subtle long-range probe of the molecular potential.
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
Conformal symmetry and differential regularization of the three-gluon vertex
NASA Astrophysics Data System (ADS)
Freedman, Daniel Z.; Grignani, Gianluca; Johnson, Kenneth; Rius, Nuria
1992-08-01
The conformal symmetry of the QCD Lagrangian for massless quarks is broken both by renormalization effects and the gauge fixing procedure. Renormalized primitive divergent amplitudes have the property that their form away from the overall coincident point singularity is fully determined by the bare Lagrangian, and scale dependence is restricted to δ-functions at the singularity. If gauge fixing could be ignored, one would expect these amplitudes to be conformal invariant for non-coincident points. We find that the one-loop three-gluon vertex function Г μvp(x, y, z) is conformal invariant in this sense, if calculated in the background field formalism using the Feynman gauge for internal gluons. It is not vet clear why the expected breaking due to gauge fixing is absent. The conformal property implies that the gluon, ghost, and quark loop contributions to Г μvp are each purely numerical combinations of two universal conformal tensors Dμvp( x, y, z) and Cμvp( x, y, z) whose explicit form is given in the text. Only Dμvp has an ultraviolet divergence, although Cμvp requires a careful definition to resolve the expected ambiguity of a formally linearly divergent quantity. Regularization is straightforward and leads to a renormalized vertex function which satisfies the required Ward identity, and from which the beta function is easily obtained. Exact conformal invariance is broken in higher-loop orders, but we outline a speculative scenario in which the perturbative structure of the vertex function is determined from a conformal invariant primitive core by interplay of the renormalization group equation and Ward identities. Other results which are relevant to the conformal property include the following: (1) An analytic calculation shows that the linear deviation from the Feynman gauge is not conformal invariant, and a separate computation using symbolic manipulation confirms that among Dμbμ background gauges, only the Feynman gauge is conformal invariant. (2
The Form Factors of the Gauge-Invariant Three-Gluon Vertex
Binger, Michael; Brodsky, Stanley J.
2006-02-24
The gauge-invariant three-gluon vertex obtained from the pinch technique is characterized by thirteen nonzero form factors, which are given in complete generality for unbroken gauge theory at one loop. The results are given in d dimensions using both dimensional regularization and dimensional reduction, including the effects of massless gluons and arbitrary representations of massive gauge bosons, fermions, and scalars. We find interesting relations between the functional forms of the contributions from gluons, quarks, and scalars. These relations hold only for the gauge-invariant pinch technique vertex and are d-dimensional incarnations of supersymmetric nonrenormalization theorems which include finite terms. The form factors are shown to simplify for N = 1, 2, and 4 supersymmetry in various dimensions. In four-dimensional non-supersymmetric theories, eight of the form factors have the same functional form for massless gluons, quarks, and scalars, when written in a physically motivated tensor basis. For QCD, these include the tree-level tensor structure which has prefactor {beta}{sub 0} = (11N{sub c}-2N{sub f})/3, another tensor with prefactor 4N{sub c} - N{sub f}, and six tensors with N{sub c} - N{sub f}. In perturbative calculations our results lead naturally to an effective coupling for the three-gluon vertex, {tilde {alpha}}(k{sub 1}{sup 2}, k{sub 2}{sup 2}, k{sub 3}{sup 2}), which depends on three momenta and gives rise to an effective scale Q{sub eff}{sup 2} (k{sub 1}{sup 2}, k{sub 2}{sup 2}, k{sub 3}{sup 2}) which governs the behavior of the vertex. The effects of nonzero internal masses M are important and have a complicated threshold and pseudo-threshold structure. A three-scale effective number of flavors N{sub F}(k{sub 1}{sup 2}/M{sup 2}, k{sub 2}{sup 2}/M{sup 2}, k{sub 3}{sup 2}/M{sup 2}) is defined. The results of this paper are an important part of a gauge-invariant dressed skeleton expansion and a related multi-scale analytic renormalization scheme
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
Low-momentum ghost dressing function and the gluon mass
Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; Gomez, M. E.; Rodriguez-Quintero, J.
2010-09-01
We study the low-momentum ghost propagator Dyson-Schwinger equation in the Landau gauge, assuming for the truncation a constant ghost-gluon vertex, as it is extensively done, and a simple model for a massive gluon propagator. Then, regular Dyson-Schwinger equation solutions (the zero-momentum ghost dressing function not diverging) appear to emerge, and we show the ghost propagator to be described by an asymptotic expression reliable up to the order O(q{sup 2}). That expression, depending on the gluon mass and the zero-momentum Taylor-scheme effective charge, is proven to fit pretty well some low-momentum ghost propagator data [I. L. Bogolubsky, E. M. Ilgenfritz, M. Muller-Preussker, and A. Sternbeck, Phys. Lett. B 676, 69 (2009); Proc. Sci., LAT2007 (2007) 290] from big-volume lattice simulations where the so-called ''simulated annealing algorithm'' is applied to fix the Landau gauge.
Transverse Flow of Gluon Fields in Heavy Ion Collision
NASA Astrophysics Data System (ADS)
Chen, Guangyao; Fries, Rainer J.
2014-09-01
We describe the dynamics of initial gluon fields in heavy ion collision using a formal recursive solution of the Yang Mills equations and solving for the energy momentum tensor analytically in a boost-invariant setup. We generalize the original McLerran-Venugopalan (MV) model in order to allow for realistic nuclear profiles. This leads to a transverse flow of gluon fields. This flow pattern is inherited by the quark gluon plasma fluid after thermalization. Its most interesting aspect is a rapidity-odd flow component. We show that this rapidity-odd flow does not break boost invariance and that it emerges naturally from the Yang Mills equations. It leads to directed flow of particles and introduces angular momentum to the system.
Polyakov loop and gluon quasiparticles in Yang-Mills thermodynamics
NASA Astrophysics Data System (ADS)
Ruggieri, M.; Alba, P.; Castorina, P.; Plumari, S.; Ratti, C.; Greco, V.
2012-09-01
We study the interpretation of lattice data about the thermodynamics of the deconfinement phase of SU(3) Yang-Mills theory, in terms of gluon quasiparticles propagating in a background of a Polyakov loop. A potential for the Polyakov loop, inspired by the strong coupling expansion of the QCD action, is introduced; the Polyakov loop is coupled to transverse gluon quasiparticles by means of a gaslike effective potential. This study is useful to identify the effective degrees of freedom propagating in the gluon medium above the critical temperature. A main general finding is that a dominant part of the phase transition dynamics is accounted for by the Polyakov loop dynamics; hence, the thermodynamics can be described without the need for diverging or exponentially increasing quasiparticle masses as T→Tc, at variance respect to standard quasiparticle models.
Structure of a confining gluon string within the field correlator method
Kozlov, I. E.; Chernodub, M. N.
2009-02-15
The structure of the chromoelectric string in the Euclidian formulation of Yang-Mills theory is studied by using multipoint correlation functions involving Wilson loop operators and the strength tensors of the gluon field. It is shown that the local densities of the action functional and the squared topological charge in the vicinity of the static-string axis must be markedly smaller than the corresponding values far off the string. Analytic results obtained in this study are in agreement with the results of a lattice simulation of Yang-Mills theory.
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.
Gluon saturation and inclusive production at low transverse momenta
NASA Astrophysics Data System (ADS)
Levin, Eugene
2010-11-01
In this paper we suggest the generalization of kT factorization formula for inclusive gluon production for the dense-dense parton system scattering. It turns out that the soft gluon production with transverse momentum pT is suppressed by an additional Sudakov-like factor that depends on the pT2/Qs2 ratio in good agreement with the first numerical calculation in the color glass condensate approach by J. P. Blaizot, T. Lappi, and Y. Mehtar-Tan.
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.
Probing the quark-gluon interaction with hadrons
NASA Astrophysics Data System (ADS)
Sanchis-Alepuz, Hèlios; Williams, Richard
2015-10-01
We present a unified picture of mesons and baryons in the Dyson-Schwinger/Bethe-Salpeter approach, wherein the quark-gluon and quark-(anti)quark interactions follow from a systematic truncation of the QCD effective action and include all its tensor structures. The masses of some of the ground-state mesons and baryons are found to be in reasonable agreement with the expectations of a 'quark-core calculation', suggesting a partial insensitivity to the details of the quark-gluon interaction. However, discrepancies remain in the meson sector, and for excited baryons, that suggest higher order corrections are relevant and should be investigated following the methods outlined herein.
Gluon saturation and inclusive production at low transverse momenta
Levin, Eugene
2010-11-15
In this paper we suggest the generalization of k{sub T} factorization formula for inclusive gluon production for the dense-dense parton system scattering. It turns out that the soft gluon production with transverse momentum p{sub T} is suppressed by an additional Sudakov-like factor that depends on the p{sub T}{sup 2}/Q{sub s}{sup 2} ratio in good agreement with the first numerical calculation in the color glass condensate approach by J. P. Blaizot, T. Lappi, and Y. Mehtar-Tan.
The hard gluon component of the QCD Pomeron
White, A.R.
1996-10-20
The authors argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Super-Critical phase of Reggeon Field Theory. That the color compensation takes place at a longer distance is consistent with the Pomeron carrying odd color charge parity.
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.
NASA Astrophysics Data System (ADS)
Bleibel, J.; Bravina, L. V.; Zabrodin, E. E.
2016-06-01
Multiplicity, rapidity and transverse momentum distributions of hadrons produced both in inelastic and nondiffractive p p collisions at energies from √{s }=200 GeV to 14 TeV are studied within the Monte Carlo quark-gluon string model. Good agreement with the available experimental data up to √{s }=13 TeV is obtained, and predictions are made for the collisions at top LHC energy √{s }=14 TeV . The model indicates that Feynman scaling and extended longitudinal scaling remain valid in the fragmentation regions, whereas strong violation of Feynman scaling is observed at midrapidity. The Koba-Nielsen-Olesen (KNO) scaling in multiplicity distributions is violated at LHC also. The origin of both maintenance and violation of the scaling trends is traced to short range correlations of particles in the strings and interplay between the multistring processes at ultrarelativistic energies.
Direct Photon Production and Gluon Polarization Measurements in Proton-Proton Collisions at PHENIX
NASA Astrophysics Data System (ADS)
Feege, Nils; Phenix Collaboration
2015-10-01
Direct photons probe the hard scattering process in proton-proton collisions. The channel that dominates their production in these collisions is ``the inverse QCD Compton effect,'' g + q --> γ + q . Calculating this process requires no photon fragmentation function, which facilitates comparisons between theories and experiments. In polarized p+p collisions, direct photons help determine the proton spin structure. At leading order, the longitudinal double-spin asymmetry ALL is directly proportional to the product of quark and gluon polarizations. The polarized quark distributions are known from polarized lepton-proton scattering experiments. Using them together with ALL measurements allows to access both the magnitude and sign of the polarized gluon distribution. The PHENIX experiment has collected data from polarized p+p collisions at RHIC at center of mass energies of 200 GeV and 500 GeV. This talk presents the status of direct photon cross section measurements and ALL measurements at midrapidity (| η | < 0 . 35) using these data.
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.
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. PMID:25479490
Towards the quark-gluon plasma Equation of State with dynamical strange and charm quarks
NASA Astrophysics Data System (ADS)
Burger, Florian; Ilgenfritz, Ernst-Michael; Lombardo, Maria Paola; Müller-Preussker, Michael; Trunin, Anton
2016-01-01
We present an ongoing project aimed at determining the thermodynamic Equation of State (EoS) of quark-gluon matter from lattice QCD with two generations of dynamical quarks. We employ the Wilson twisted mass implementation for the fermionic fields and the improved Iwasaki gauge action. Relying on T = 0 data obtained by the ETM Collaboration the strange and charm quark masses are fixed at their physical values, while the pion mass takes four values in the range from 470 MeV down to 210 MeV. The temperature is varied within a fixed-lattice scale approach. The values for the pseudocritical temperature are obtained from various observables. For the EoS we show preliminary results for the pure gluonic contribution obtained at the pion mass value 370 MeV, where we can compare with previously obtained results with Nf = 2 degenerate light flavours.
ERIC Educational Resources Information Center
Rayner, Keith; Juhasz, Barbara J.; Brown, Sarah J.
2007-01-01
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…
Z -peaked excess from heavy gluon decays to vectorlike quarks
NASA Astrophysics Data System (ADS)
Vignaroli, Natascia
2015-06-01
A 3 sigma excess has been recently announced by ATLAS in events with Z -peaked dilepton pairs, jets, and large transverse missing energy. We interpret this finding in the context of composite Higgs/Randall-Sundrum theories. We find that composite Higgs theories with custodial symmetry protection to the Z b b ¯ coupling predict a significant contribution to Z Z b b (and to h h b b ) final states coming from heavy gluon decays to pairs of bottom partner vectorlike quarks. The heavy gluon to vectorlike quark signal is largely accepted by the ATLAS selection if one of the Z bosons in the Z Z b b final state decays leptonically and the other to neutrinos. For a bottom partner of ˜900 GeV , we find that the ATLAS excess can be reproduced by composite Higgs models, in an experimentally allowed parameter space, for heavy gluon masses roughly in a range 1.87-2.15 TeV and for heavy gluon couplings to light quarks within ˜(0.3 - 0.65 )gS . We briefly discuss the implication of this result for future experimental tests.
Synchrotron contribution to photon emission from quark-gluon plasma
NASA Astrophysics Data System (ADS)
Zakharov, B. G.
2016-08-01
We study the inuence of the magnetic field on the photon emission from the quark-gluon plasma created in AA collisions. We find that even for very optimistic assumption on the magnitude of the magnetic field for noncentral AA collisions the effect of magnetic field is very small.
Gluon transport equations with condensate in the small angle approximation
NASA Astrophysics Data System (ADS)
Blaizot, Jean-Paul; Liao, Jinfeng
2016-05-01
We derive the set of kinetic equations that control the evolution of gluons in the presence of a condensate. We show that the dominant singularities remain logarithmic when the scattering involves particles in the condensate. This allows us to define a consistent small angle approximation.
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.
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.
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)
Snyder, Douglas
2013-04-01
The proposed experiment relies on a delayed choice whether or not to keep the entanglement between paired signal and idler photons where the idler photon provides which way information to a distant signal photon. One can produce an overall distribution of the signal photons showing interference by losing the idler photons in many other similar photons over many experimental runs or instead an overall which way distribution for the signal photons at a distance by not losing their paired idler photons over many experimental runs. The idler photon is either detected or lost before the entangled signal photon is detected. The overall which way or non which way distributions (the latter exhibiting interference) for the signal photons are not dependent on correlating measurement results on the paired signal and idler photons. Ultrafast switches (such as that of Hall, Altepeter, and Kumar, http://iopscience.iop.org/1367-2630/13/10/105004/fulltext/) can be used to change the paths for the idler photon while the idler photon is in flight. Optical microcavities filled with photons similar to the idler photon can be used to lose the idler photon. The method underlying the experiment is described. One reference to the delayed choice method proposed here is: http://meetings.aps.org/link/BAPS.2012.MAR.K1.303.
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.
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)
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.
Double distributions and evolution equations
A.V. Radyushkin
1998-05-01
Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive meson electroproduction processes require a generalization of usual parton distributions for the case when long-distance information is accumulated in nonforward matrix elements < p{prime} {vert_bar}O(0,z){vert_bar}p > of quark and gluon light-cone operators. In their previous papers the authors used two types of nonperturbative functions parameterizing such matrix elements: double distributions F(x,y;t) and nonforward distribution functions F{sub {zeta}}(X;t). Here they discuss in more detail the double distributions (DD's) and evolution equations which they satisfy. They propose simple models for F(x,y;t=0) DD's with correct spectral and symmetry properties which also satisfy the reduction relations connecting them to the usual parton densities f(x). In this way, they obtain self-consistent models for the {zeta}-dependence of nonforward distributions. They show that, for small {zeta}, one can easily obtain nonforward distributions (in the X > {zeta} region) from the parton densities: F{sub {zeta}} (X;t=0) {approx} f(X{minus}{zeta}/2).
Zykunov, V. A.
2010-07-15
With an eye to future experiments at the Large Hadron Collider (LHC), O(aa{sub s}) QCD corrections to the Drell-Yan process are calculated for vertex functions and gluon bremsstrahlung. Use is made of fully differential cross sections, so that the result obtained in the present study can readily be applied in analyzing experimental data (in correcting data from future experiments at LHC). It is shown both analytically and numerically that the results are independent of unphysical parameters, including the parameter separating the regions of soft and hard gluons and the quark mass. A numerical analysis of radiative effects was performed by means of the FORTRAN code READY with allowance for the experimental cuts used at the Compact Muon Solenoid (CMS) detector
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. PMID:25303243
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
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.
Bottomonia in the Quark Gluon Plasma
NASA Astrophysics Data System (ADS)
Strickland, Michael
2013-04-01
I review recent calculations of the suppression of bottomonium states in heavy ion collisions. A non-relativistic potential is used which is complex valued. This allows one to extract the binding energies and decay widths of the ground and excited states of bottomonium as a function of the typical plasma particle momentum and momentum-space anisotropy. The decay widths determined are used as input and integrated over space-time taking into account the dynamical evolution of the typical particle momentum and momentum-space anisotropy. The suppression of Upsilon(1s), Upsilon(2s), Upsilon(3s), χb1, and χb2 is obtained as a function of centrality, rapidity, and transverse momentum. The obtained results are compared with data from the STAR and CMS collaborations.
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. PMID:14754324
Quark-Gluon Soup -- The Perfectly Liquid Phase of QCD
NASA Astrophysics Data System (ADS)
Heinz, Ulrich
2015-03-01
At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.
The physics of hot and dense quark-gluon matter
Kharzeev, Dmitri E
2012-05-10
This technical report describes the work done under the DOE grant DE-FG-88ER41723 (final award number DE-SC0005645), "The physics of hot and dense quark-gluon matter", during the year of 12/01/2010 through 11/30/2011. As planned in the proposal, the performed research focused along two main thrusts: 1) topological effects in hot quark-gluon matter and 2) phenomenology of relativistic heavy ion collisions. The results of research are presented in 12 papers published in reputable refereed journals (Physical Review Letters, Physical Review, Physics Letters and Nuclear Physics). All of the performed research is directly related to the experimental programs of DOE, especially at the Relativistic Heavy Ion Collider. Much of it also has broader interdisciplinary implications - for example, the work on the non-dissipative chiral magnetic current is directly relevant for quantum computing. The attached report describes the performed work in detail.
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
Jouzani, Gholamreza Salehi; Abad, Ali Pourjan; Seifinejad, Ali; Marzban, Rasoul; Kariman, Khalil; Maleki, Bahram
2008-02-01
One hundred and twenty-eight Bacillus thuringiensis isolates from fields of different ecological regions of Iran were collected to study the distribution and diversity of Dipteran-specific cry and cyt genes. The percentage of samples with Bt showed significant differences between different regions and also between different fields. The most Bt frequency was observed in the soil samples collected from Caspianic zone (7%) and soils of cotton (17%). Characterization of isolates was based on morphological characteristics of crystals, plasmid profiles and protein band patterns as well as PCR analysis using general and specific primers for 22 different cry and cyt genes encoding proteins active against mosquitoes. Thirty-eight different cry gene profiles were detected in this collection. Several of them were found to be different from all previously published profiles and none of the previous researches reported these numbers of profiles. Strains containing cry2-type genes were the most abundant and represent 57.1% of the isolates. Strains harboring cry24 and cry10 genes were also highly abundant (38.7 and 32.8%, respectively). cry11, cry4, cry17, cry19, cry21, cry29, cyt1, and cry9 genes were less abundant, found in 25.7, 14.3, 11.4, 1.4, 4.3, 1.4, and 10% of the strains, respectively. Among the cry2 gene containing isolates, 37.5% strains harbored cry2Aa, 55% cry2Ab, 2.5% cry2Ac, and 5% other or novel cry2-type genes. Among the cry4 gene containing isolates, 0% strains harbored cry4A, 60% cry4B, and 40% cry4C, cry4D or novel cry4 type genes. Finally, based on crystal morphology, protein patterns and PCR, 21 strains were selected as potentially high Dipteran-active for bioassays. Also our results showed that some of the isolates may harbor minimum a putative novel cry gene. PMID:17999100
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
From quarks and gluons to baryon form factors
Eichmann, Gernot
2012-01-01
I briefly summarize recent results for nucleon and Δ(1232) electromagnetic, axial and transition form factors in the Dyson–Schwinger approach. The calculation of the current diagrams from the quark–gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects. PMID:26766879
Analytic structure of Landau gauge ghost and gluon propagators
NASA Astrophysics Data System (ADS)
Strauss, Stefan; Fischer, Christian S.; Kellermann, Christian
2012-04-01
We summarize first explicit results for the analytic structure of the ghost and gluon propagators in the complex momentum plane. To this end we work in Landau gauge and use a truncation of the Dyson-Schwinger equations for the propagators which is close to lattice results at real spacelike Euclidean momenta. Our results indicate the absence of singularities in the complex part of the momentum plane contrary to expectations from Gribov-Zwanziger-like effective theories.
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.
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.
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.
Nonlinear dynamics of soft fermion excitations in hot QCD plasma I: Soft-quark soft-gluon scattering
NASA Astrophysics Data System (ADS)
Markov, Yu. A.; Markova, M. A.
2006-05-01
Within the framework of the hard thermal loop effective theory we derive a system of Boltzmann-like kinetic equations taking into account the simplest processes of nonlinear interaction of soft fermionic and bosonic QCD plasma excitations: elastic scattering of soft-(anti)quark excitations off soft-gluon and soft-quark excitations, pair production of soft quark-antiquark excitations, annihilation into two soft-gluon excitations. The matrix elements of these processes to leading order in the coupling constant g are obtained. The iterative method of calculation of the matrix elements for the higher processes of soft-mode interactions is proposed. The most general expression for the emitted radiant power induced by the effective currents and effective sources in a quark-gluon plasma (QGP) taking into account an existence of fermion sector of plasma excitations is defined. The explicit form of the linearized Boltzmann equation accounting for scattering of color(less) plasminos off color(less) plasmons is written out.
NASA Astrophysics Data System (ADS)
Zhou, Li-Juan; Zheng, Bo; Zhong, Hong-Wei; Ma, Wei-Xing
2015-03-01
Based on the Dyson-Schwinger Equations (DSEs), the two-quark vacuum condensate, the four-quark vacuum condensate, and the quark gluon mixed vacuum condensate in the non-perturbative QCD vacuum state are investigated by solving the DSEs with rainbow truncation at zero- and finite- temperature, respectively. These condensates are important input parameters in QCD sum rule with zero and finite temperature, and in studying hadron physics, as well as predicting the quark mean squared momentum m20- also called quark virtuality in the QCD vacuum state. The present calculated results show that these physical quantities are almost independent of the temperature below the critical point temperature Tc = 131 MeV, and above Tc the chiral symmetry is restored. For comparison we calculate the temperature dependence of the “in-hadron condensate” for pion. At the same time, we also calculate the ratio of the quark gluon mixed vacuum condensate to the two-quark vacuum condensate by using these condensates, and the unknown quark mean squared momentum in the QCD vacuum state has been obtained. The results show that the ratio m20(T) is almost flat in the temperature region from 0 to Tc, although there are drastic changes of the quark vacuum condensate and the quark gluon mixed vacuum condensate at the region. Our predicted ratio comes out to be m20(T)=2.41 GeV2 at the Chiral limit, which is consistent with other theory model predictions, and strongly indicates the significance that the quark gluon mixed vacuum condensate has played in the virtuality calculations. Supported by National Natural Science Foundation of China (11365002), Guangxi Natural Science Foundation for Young Researchers (2013GXNSFBB053007, 2011GXNSFA018140), Guangxi Education Department (2013ZD049), Guangxi Grant for Excellent Researchers (2011-54), and Guangxi University of Science and Technology Foundation for PhDs (11Z16)
Observation of Tree-Level B Decays with s smacr Production from Gluon Radiation
NASA Astrophysics Data System (ADS)
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.
2008-05-01
We report on our search for decays proceeding via a tree-level b→c quark transition in which a gluon radiates into an s smacr pair. We present observations of the decays B-→Ds(*)+K-π- and Bmacr 0→Ds+KS0π- and evidence for B-→Ds+K-K- and set upper limits on the branching fractions for Bmacr 0→Ds*+KS0π- and B-→Ds*+K-K- using 383×106 Υ(4S)→B Bmacr events collected by the BABAR detector at SLAC. We present evidence that the invariant mass distributions of Ds(*)+K- pairs from B-→Ds(*)+K-π- decays are inconsistent with the phase-space model, suggesting the presence of charm resonances lying below the Ds(*)+K- threshold.
Gluons to Diphotons via New Particles with Half the Signal's Invariant Mass
NASA Astrophysics Data System (ADS)
Chway, Dongjin; Dermíšek, Radovan; Jung, Tae Hyun; Kim, Hyung Do
2016-08-01
Any new particle charged under S U (3 )C and carrying an electric charge will leave an imprint in the diphoton invariant mass spectrum, as it can mediate the g g →γ γ process through loops. The combination of properties of loop functions, threshold resummation, and gluon parton distribution functions can result in a peaklike feature in the diphoton invariant mass around twice the mass of a given particle even if the particle is short lived, and thus it does not form a narrow bound state. Using a recent ATLAS analysis, we set upper limits on the combined S U (3 )C and electric charge of new particles and indicate future prospects. We also discuss the possibility that the excess of events in the diphoton invariant mass spectrum around 750 GeV originates from loops of a particle with a mass of around 375 GeV.
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
2008-05-01
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. PMID:18518280
Nonplanar 4-Jets in Quarkonium Decays as a Probe for 3-Gluon Coupling
NASA Astrophysics Data System (ADS)
Muta, T.; Niuya, T.
1982-11-01
We calculate the acoplanarity (à la Fox-Wolfram) distribution of 4 jets generated by orthoquarkonium decays: 3S1(Qbar{Q})→ GGGG, GGqbar{q}. The result shows that the deviation from planar event due to 4 jets is significantly large showing the importance of the effect of 3-gluon couplings in quantum chromodynamics. The average acoplanarity
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.
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 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)
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.
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.
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.
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.
Photon gluon fusion cross sections at HERA energy
NASA Astrophysics Data System (ADS)
Engelen, J. J.; Dejong, S. J.; Poletiek, M.; Vermaseren, J. A. M.
1988-01-01
Cross sections for heavy flavor production through photon gluon fusion in electron proton collisions are presented. The electron photon vertex is taken into account explicitly, and the Q sq of the exchanged photon ranges from nearly zero (almost real photon) to the kinematically allowed maximum. The QCD scale is set by the mass of the produced quarks. The formalism is also applicable to the production of light quarks as long as the invariant mass of the pair is sufficiently high, so cross sections for u anti-u, d anti-d, and s anti-s production are also given.
Polarized Quarks, Gluons and Sea in Nucleon Structure Functions
NASA Astrophysics Data System (ADS)
Bourrely, C.; Buccella, F.; Pisanti, O.; Santorelli, P.; Soffer, J.
1998-06-01
We perform a NLO analysis of polarized deep inelastic scattering data to test two different solutions to the so-called spin crisis, one of them based on the axial gluon anomaly and consistent with the Bjorken sum rule, and another in which the defects in the spin sum rules and in the Gottfried sum rule are related. In this case a defect is also expected for the Bjorken sum rule. The first solution is slightly favoured by the SLAC E154 results, but both options seem to be consistent with the CERN SMC data.
Heavy quarks, gluons and the confinement potential in Coulomb gauge
NASA Astrophysics Data System (ADS)
Popovici, Carina; Watson, Peter; Reinhardt, Hugo
2011-05-01
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.
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.
Jet-conversion photons from an anisotropic quark-gluon plasma
NASA Astrophysics Data System (ADS)
Bhattacharya, Lusaka; Roy, Pradip
2010-10-01
We calculate the pT distributions of jet-conversion photons from a quark-gluon plasma with pre-equilibrium momentum-space anisotropy. A phenomenological model has been used for the time evolution of the hard momentum scale phard(τ) and anisotropy parameter ξ(τ). As a result of pre-equilibrium momentum-space anisotropy, we find significant modification of the jet-conversion photon pT distribution. For example, with fixed initial condition pre-equilibrium anisotropy, we predict a significant enhancement of the jet-photon pT distribution in the entire region, whereas for pre-equilibrium anisotropy with fixed final multiplicity (FFM), suppression of the jet-conversion photon pT distribution is observed. The results with FFM (as it is the most realistic situation) have been compared with high pT PHENIX photon data. It is found that the data are reproduced well if the isotropization time lies within 1.5 fm/c.
High precision determination of the gluon fusion Higgs boson cross-section at the LHC
NASA Astrophysics Data System (ADS)
Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Lazopoulos, Achilleas; Mistlberger, Bernhard
2016-05-01
We present the most precise value for the Higgs boson cross-section in the gluon-fusion production mode at the LHC. Our result is based on a perturbative expansion through N3LO in QCD, in an effective theory where the top-quark is assumed to be infinitely heavy, while all other Standard Model quarks are massless. We combine this result with QCD corrections to the cross-section where all finite quark-mass effects are included exactly through NLO. In addition, electroweak corrections and the first corrections in the inverse mass of the top-quark are incorporated at three loops. We also investigate the effects of threshold resummation, both in the traditional QCD framework and following a SCET approach, which resums a class of π2 contributions to all orders. We assess the uncertainty of the cross-section from missing higher-order corrections due to both perturbative QCD effects beyond N3LO and unknown mixed QCD-electroweak effects. In addition, we determine the sensitivity of the cross-section to the choice of parton distribution function (PDF) sets and to the parametric uncertainty in the strong coupling constant and quark masses. For a Higgs mass of m H = 125 GeV and an LHC center-of-mass energy of 13 TeV, our best prediction for the gluon fusion cross-section is σ =48.58{pb}_{-3.27pb}^{+2.22pb}(theory)± 1.56pb(3.20%)(PDF+{α}_s).
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.
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. PMID:26918981
Study of the subjet structure of quark and gluon jets
NASA Astrophysics Data System (ADS)
Buskulic, D.; Casper, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Ariztizabal, F.; Chmeissani, M.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Sanchez, F.; Teubert, F.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Engelhardt, A.; Forty, R. W.; Frank, M.; Ganis, G.; Girone, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Maggi, M.; Markou, C.; Martin, E. B.; Mato, P.; Meinhard, H.; Minten, A.; Miquel, R.; Palazzi, P.; Pater, J. R.; Perrodo, P.; Pusztaszeri, J.-F.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Venturi, A.; Wachsmuth, H.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Barres, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J.-M.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Johnson, S. D.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Passalacqua, L.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Pepe-Altarelli, M.; Salomone, S.; Colrain, P.; Ten Have, I.; Knowles, I. G.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Thorn, S.; Turnbull, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Colling, D. J.; Dornan, P. J.; Konstantinidis, N.; Moneta, L.; Moutoussi, A.; Nash, J.; San Martin, G.; Sedgbeer, J. K.; Stacey, A. M.; Dissertori, G.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Walther, S. M.; Wanke, R.; Wolf, B.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Thulasidas, M.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Dietl, H.; Dydak, F.; Gotzhein, C.; Halley, A. W.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Denis, R. St.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Courault, F.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Musolino, G.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Gao, Y.; Green, M. G.; Johnson, D. L.; Medcalf, T.; Mir, Ll. M.; Strong, J. A.; Bertin, V.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Maley, P.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Trabelsi, A.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Beddall, A.; Booth, C. N.; Boswell, R.; Cartwright, S.; Combley, F.; Dawson, I.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Feigl, E.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Schäfer, U.; Smolik, L.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Pitis, L.; Ragusa, F.; Kim, H.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration
1995-02-01
Measurements of the subjet structure of quark and gluon jets in hadronic Z decays are presented. The analysis is based on one million hadronic events recorded by the ALEPH detector. Roughly symmetric three-jet events are selected with a coarse jet-resolution cut-off, y1. Gluon jets are identified with a purity of 94.6% in those events where evidence of long-lived heavy-flavour hadrons in the other two jets is found. The jets are then analyzed using a smaller cut-off y0 (< y1) so that subjets are resolved. The properties of the jets (subjet multiplicities ( Nq), ( Ng) and rates Rng( q) for n = 1, 2, 3, 4) are determined and are found to be in good agreement with the expectations of perturbative QCD as long as the subjet resolution parameter y0 is sufficiently large to keep non-perturbative effects small. In particular, the ratio {(N g - 1) }/{(N q - 1) }, which to leading order in QCD is given by the ratio of colour factors {C A}/{C F} = {9}/{4}, is measured to be 1.96 ± 0.15 for y0 = 2 · 10 -3, but falls to 1.29 ± 0.03 for y0 = 1.6 · 10 -5.
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
NASA Astrophysics Data System (ADS)
Tuchin, Kirill
2016-05-01
A quark propagating through the quark gluon plasma and scattering off the thermal gluons can radiate photons in states with definite angular momentum and magnetic helicity. These states, known as the Chandrasekhar-Kendall states, are eigenstates of the curl operator and have a nontrivial topology. I compute the spectrum of these states in the ultrarelativistic limit and study its properties.
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
A measurement of quark and gluon jet differences at the Z{sup 0} resonance
Iwasaki, Yoshihito
1994-08-01
The authors have studied differences between quark and gluon jets using 3-jet events in hadronic decays of Z{sup 0} bosons collected by the SLD experiment at SLAC. Gluon jets were identified in symmetric 3-jet events containing one jet tagged as a heavy quark jet and compared with a mixed sample of quark and gluon jets and also with a mixed sample of light quark (u, d and s) and gluon jets. Their preliminary results show that the particle multiplicity in gluon jets is higher than that in light quark jets. These results are in qualitative agreement with QCD expectations. Differences are also observed in particle energy spectra and the jet widths, consistent with QCD expectations.
Quark and gluon jet properties in symmetric three-jet events
NASA Astrophysics Data System (ADS)
Buskulic, D.; Casper, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Farilla, A.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palazzi, P.; Pater, J. R.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Colling, D. J.; Dornan, P. J.; Moutoussi, A.; Nash, J.; San Martin, G.; Sedgbeer, J. K.; Stacey, A. M.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Johnson, D. L.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Maley, P.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Beddall, A.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Feigl, E.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration
1996-02-01
Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on a track impact parameter method. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity, Evidence is presented which shows that the corresponding differences between gluon and b jets are significantly smaller. In a statistically limited comparison the multiplicity in c jets was found to be comparable with that observed for the jets of mixed quark flavour.
Behaviors of Early Time Gluon Fields in High Energy Nuclear Collisions
NASA Astrophysics Data System (ADS)
Chen, Guangyao; Fries, Rainer
2010-11-01
We discuss the properties of the early time gluon fields in ultra-relativistic heavy ion collisions in a quasi-classical approximation. Using recursive solutions of the Yang-Mills equations for two intersecting color currents on the light cone, we describe the classical gluon field and its energy momentum tensor at small proper times τ after the collision of two nuclei. We explicitly check energy momentum conservation up to forth order. We compute multi-gluon correlation functions in the McLerran-Venugopalan model which are necessary to calculate the expectation value of the energy momentum tensor. An interpolation with linear gluon fields at large times provides a good approximation of the full time evolution. Our results can also be used to create an event-by- event sample of early time gluon fields.
NASA Astrophysics Data System (ADS)
Li, Xuan; Star Collaboration
2014-09-01
The STAR experiment at RHIC is carrying out a comprehensive high-energy spin physics program to understand the internal structure and dynamics of the proton in polarized proton-proton collisions at = 200 GeV and = 500/510 GeV. STAR has the capability, with nearly full azimuthal coverage, to reconstruct leptons, hadrons and jets in the mid-rapidity region (|η| < 1). The results for inclusive jet longitudinal double spin asymmetries taken during the 2009 RHIC run indicate the first non-zero gluon contribution (Δg(x,Q2)/g(x,Q2)) to the proton spin for 0.05 < x < 1 (Bjorken-x: momentum fraction of partons). Recent longitudinal single-spin asymmetry measurements of W+/- bosons at = 500/510 GeV in polarized proton-proton collisions provide a direct probe of the polarized anti-u and anti-d quark distributions (Δū(x, Q2), Δbar d(x, Q2)). These results better constrain the polarized gluon and sea quark distributions of the proton in the RHIC sensitive kinematic region. Future measurements with continuing high energy polarized proton-proton run at RHIC and detector upgrade will explore the gluonic contribution to the proton spin in extended range.
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.
Nonfactorizable soft gluons in nonleptonic heavy meson decays
Li, H.; Tseng, B.
1998-01-01
We include nonfactorizable soft gluon corrections to the perturbative QCD formalism for exclusive nonleptonic heavy meson decays, which combines factorization theorems and effective field theory. These corrections are classified according to their color structures, and exponentiated separately to complete the Sudakov resummation up to next-to-leading logarithms. The nonfactorizable contributions in nonleptonic decays are clearly identified in our formalism, and found to be positive for bottom decays and negative for charm decays. Our analysis confirms that the large-N{sub c} approximaton is applicable to charm decays, but not to bottom decays, consistent with the phenomenological implications of experimental data. The comparision of our predictions with those from QCD sum rules is also made. {copyright} {ital 1997} {ital The American Physical Society}
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.
Gluon-fusion contributions to {Phi}+2 jet production
Campanario, F.; Zeppenfeld, D.; Kubocz, M.
2011-11-01
In high energy hadronic collisions, a scalar or pseudoscalar Higgs boson, {Phi}=H, A, can be efficiently produced via gluon fusion, which is mediated by heavy quark loops. In this paper, we consider double real emission corrections to {Phi}=A production, which lead to a Higgs plus two-jet final state, at order {alpha}{sub s}{sup 4}. Full quark mass effects are considered in the calculation of scattering amplitudes for the CP-odd Higgs boson A, as induced by quark triangle-, box-, and pentagon-diagrams. They complement the analogous results for a CP-even Higgs boson H in Ref. [1]. Interference effects between loops with top and bottom quarks as well as between CP-even and CP-odd couplings of the heavy quarks are fully taken into account.
Gluon fragmentation into quarkonium at next-to-leading order
NASA Astrophysics Data System (ADS)
Artoisenet, Pierre; Braaten, Eric
2015-04-01
We present the first calculation at next-to-leading order (NLO) in α s of a fragmentation function into quarkonium whose form at leading order is a nontrivial function of z, namely the fragmentation function for a gluon into a spin-singlet S-wave state at leading order in the relative velocity. To calculate the real NLO corrections, we introduce a new subtraction scheme that allows the phase-space integrals to be evaluated in 4 dimensions. We extract all ultraviolet and infrared divergences in the real NLO corrections analytically by calculating the phase-space integrals of the subtraction terms in 4 - 2 ɛ dimensions. We also extract the divergences in the virtual NLO corrections analytically, and detail the cancellation of all divergences after renormalization. The NLO corrections have a dramatic effect on the shape of the fragmentation function, and they significantly increase the fragmentation probability.
Quantum simulations of strongly coupled quark-gluon plasma
Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.
2011-09-15
A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the model developed by B.A. Gelman, E.V. Shuryak, and I. Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces and turn out to be colorless. At the temperature as large as twice the critical one no bound states are observed. Quantum effects turned out to be of prime importance in these simulations.
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
Two-Photon and Two-gluon Decays of 0{sup ++} and 2{sup ++} P-wave Heavy Quarkonium States
Pham, T. N.
2010-12-22
By neglecting the relative quark momenta in the propagator term, the two-photon and two-gluon decay amplitude of heavy quarkonia states can be written as a local heavy quark field operator matrix element which could be obtained from other processes or computed with QCD sum rules technique or lattice simulation, as shown in a recent work on {eta}{sub c,b} two-photon decays. In this talk, I would like to discuss a similar calculation on P-wave {chi}{sub c0,2} and {chi}{sub b0,2} two-photon decays. We show that the effective Lagrangian for the two-photon decays of the P-wave {eta}{sub c0,2} and {chi}{sub b0,2} is given by the heavy quark energy-momentum tensor local operator and its trace, the QQ scalar density. A simple expression for {chi}c0 two-photon and two-gluon decay rate in terms of the f{sub {chi}c0} decay constant, similar to that of {eta}{sub c} is obtained. From the existing QCD sum rules value for f{sub {chi}c0,} we get 5 keV for the {chi}{sub c0} two-photon width, somewhat larger than measurement.
NASA Astrophysics Data System (ADS)
Alkofer, Reinhard; Fischer, Christian S.; Llanes-Estrada, Felipe J.; Schwenzer, Kai
2009-01-01
The infrared behavior of the quark-gluon vertex of quenched Landau gauge QCD is studied by analyzing its Dyson-Schwinger equation. Building on previously obtained results for Green functions in the Yang-Mills sector, we analytically derive the existence of power-law infrared singularities for this vertex. We establish that dynamical chiral symmetry breaking leads to the self-consistent generation of components of the quark-gluon vertex forbidden when chiral symmetry is forced to stay in the Wigner-Weyl mode. In the latter case the running strong coupling assumes an infrared fixed point. If chiral symmetry is broken, either dynamically or explicitly, the running coupling is infrared divergent. Based on a truncation for the quark-gluon vertex Dyson-Schwinger equation which respects the analytically determined infrared behavior, numerical results for the coupled system of the quark propagator and vertex Dyson-Schwinger equation are presented. The resulting quark mass function as well as the vertex function show only a very weak dependence on the current quark mass in the deep infrared. From this we infer by an analysis of the quark-quark scattering kernel a linearly rising quark potential with an almost mass independent string tension in the case of broken chiral symmetry. Enforcing chiral symmetry does lead to a Coulomb type potential. Therefore, we conclude that chiral symmetry breaking and confinement are closely related. Furthermore, we discuss aspects of confinement as the absence of long-range van der Waals forces and Casimir scaling. An examination of experimental data for quarkonia provides further evidence for the viability of the presented mechanism for quark confinement in the Landau gauge.
Transverse spin and classical gluon fields: Combining two perspectives on hadronic structure
NASA Astrophysics Data System (ADS)
Sievert, Matthew D.
In recent decades, the spin and transverse momentum of quarks and gluons were found to play integral roles in the structure of the nucleon. Simultaneously, the onset of gluon saturation in hadrons and nuclei at high energies was predicted to result in a new state of matter dominated by classical gluon fields. Understanding both of these contributions to hadronic structure is essential for current and future collider phenomenology. In this Dissertation, we study the combined effects of transverse spin and gluon saturation using the Glauber-Gribov-Mueller / McLerran-Venugopalan model of a heavy nucleus in the quasi-classical approximation. We investigate the use of a transversely-polarized projectile as a probe of the saturated gluon fields in the nucleus, finding that the transverse spin asymmetry of produced particles couples to the component of the gluon fields which is antisymmetric under both time reversal and charge conjugation. We also analyze the effects of saturation on the transverse spin asymmetry (Sivers function) of quarks within the wave function of the nucleus, finding that gluon saturation preferentially generates the asymmetry through the orbital angular momentum of the nucleons, together with nuclear shadowing.
Intrinsic glue distribution at very small x
NASA Astrophysics Data System (ADS)
Jalilian-Marian, Jamal; Kovner, Alex; McLerran, Larry; Weigert, Heribert
1997-05-01
We compute the distribution functions for gluons at very small x and not too large values of transverse momenta. We extend the McLerran-Venugopalan model by using renormalization group methods to integrate out effects due to those gluons which generate an effective classical charge density for Weizsäcker-Williams fields. We argue that this model can be extended from the description of nuclei at small x to the description of hadrons at yet smaller values of x. This generates a Lipatov-like enhancement for the intrinsic gluon distribution function and a nontrivial transverse momentum dependence as well. We estimate the transverse momentum dependence for the distribution functions, and show how the issue of unitarity is resolved in lepton-nucleus interactions.
Equation of state and initial temperature of quark gluon plasma at RHIC
NASA Astrophysics Data System (ADS)
Csanád, Máté; Májer, Imre
2012-08-01
In gold-gold collisions of the Relativistic Heavy Ion Collider a perfect fluid of strongly interacting quark gluon plasma (sQGP) is created. The time evolution of this fluid can be described by hydrodynamical models. After an expansion, hadrons are created during the freeze-out period. Their distribution reveals information about the final state. To investigate the time evolution one needs to analyze penetrating probes: e.g. direct photon observations. In this paper we analyze a 1+3 dimensional solution of relativistic hydrodynamics. We calculate momentum distribution, azimuthal asymmetry and momentum correlations of direct photons. Based on earlier fits to hadronic spectra, we compare photon calculations to measurements to determine the equations of state and the initial temperature of sQGP. We find that the initial temperature in the center of the fireball is 507±12 MeV, while for the sound speed we get c s=0.36±0.02. We also estimate a systematic error of these results. We find that the measured azimuthal asymmetry is also compatible with this model. We also predict a photon source that is significantly larger in the out direction than in the side direction.
Equation of state and initial temperature of quark gluon plasma at RHIC
NASA Astrophysics Data System (ADS)
Csanád, Máté; Májer, Imre
2012-08-01
In gold-gold collisions of the Relativistic Heavy Ion Collider a perfect fluid of strongly interacting quark gluon plasma (sQGP) is created. The time evolution of this fluid can be described by hydrodynamical models. After an expansion, hadrons are created during the freeze-out period. Their distribution reveals information about the final state. To investigate the time evolution one needs to analyze penetrating probes: e.g. direct photon observations. In this paper we analyze a 1+3 dimensional solution of relativistic hydrodynamics. We calculate momentum distribution, azimuthal asymmetry and momentum correlations of direct photons. Based on earlier fits to hadronic spectra, we compare photon calculations to measurements to determine the equations of state and the initial temperature of sQGP. We find that the initial temperature in the center of the fireball is 507±12 MeV, while for the sound speed we get c s =0.36±0.02. We also estimate a systematic error of these results. We find that the measured azimuthal asymmetry is also compatible with this model. We also predict a photon source that is significantly larger in the out direction than in the side direction.
Probing transverse momentum dependent parton distributions in charmonium and bottomonium production
NASA Astrophysics Data System (ADS)
Mukherjee, Asmita; Rajesh, Sangem
2016-03-01
We propose the study of unpolarized transverse momentum dependent gluon parton distributions as well as the effect of linearly polarized gluons on transverse momentum and rapidity distributions of J /ψ and ϒ production within the framework of transverse momentum dependent factorization employing a color evaporation model (CEM) in an unpolarized proton-proton collision. We estimate the transverse momentum and rapidity distributions of J /ψ and ϒ at LHCb, RHIC and AFTER energies using TMD evolution formalism.
Effective vertex of quark production in collision of a Reggeized quark and gluon
NASA Astrophysics Data System (ADS)
Kozlov, M. G.; Reznichenko, A. V.
2015-12-01
We calculate the effective vertex of the quark production in the collision of a Reggeized quark and a Reggeized gluon in the next-to-leading order (NLO). The vertex in question is the missing component of the multi-Regge NLO amplitudes with the quark and gluon exchanges in the ti channels. This multi-Regge form of the amplitudes is the important hypothesis which was recently proved for the gluon exchanges only and remains unverified within the next-to-leading-logarithmic approximation (NLA) for the general case including the quark exchanges. Our calculation allows one to develop the bootstrap approach to the quark Reggeization proof in NLA.
J/ψ-PRODUCTION Mechanisms and Determination of the Gluon Density at Hera
NASA Astrophysics Data System (ADS)
Jung, H.; Schuler, G. A.; Terron, J.
We discuss photo- and leptoproduction of J/ψ mesons at energies ranging from those of fixed-target experiments up to those of HERA. Elastic and diffractive production as well as various inelastic processes are studied. We investigate the range in which J/ψ production is described by photon-gluon fusion in the color-singlet model. We show how inelastic J/ψ production at HERA can be used to extract the gluon density. We estimate an accessible range of 3×10-4
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.
Gluon transport equation with effective mass and dynamical onset of Bose-Einstein condensation
NASA Astrophysics Data System (ADS)
Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng
2016-05-01
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. 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.
NASA Astrophysics Data System (ADS)
Dudal, D.; Oliveira, O.; Vandersickel, N.
2010-04-01
We consider the gluon propagator D(p2) at various lattice sizes and spacings in the case of pure SU(3) Yang-Mills gauge theories using the Landau gauge fixing. We discuss a class of fits in the infrared region in order to (in)validate the tree level analytical prediction in terms of the (refined) Gribov-Zwanziger framework. It turns out that an important role is played by the presence of the widely studied dimension two gluon condensate ⟨A2⟩. Including this effect allows to obtain an acceptable fit around 1 to 1.5 GeV, while corroborating the refined Gribov-Zwanziger prediction for the gluon propagator. We also discuss the infinite volume extrapolation, leading to the estimate D(0)=8.3±0.5GeV-2. As a by-product, we can also provide the prediction ⟨g2A2⟩≈3GeV2 obtained at the renormalization scale μ=10GeV.
Effect of the gluon condensate on the holographic heavy quark potential
Kim, Youngman; Lee, Bum-Hoon; Park, Chanyong; Sin, Sang-Jin
2009-11-15
The gluon condensate is very sensitive to the QCD deconfinement transition since its value changes drastically with the deconfinement transition. We calculate the gluon condensate dependence of the heavy quark potential in AdS/CFT to study how the property of the heavy quarkonium is affected by a relic of the deconfinement transition. We observe that the heavy quark potential becomes deeper as the value of the gluon condensate decreases. We interpret this as a dropping of the heavy quarkonium mass just above the deconfinement transition. We finally argue that dropping of the gluon condensate and the pure thermal effect are competing with each other in the physics of heavy quarkonium at high temperature.
On inclusive gluon jet production off the nucleus in perturbative QCD
NASA Astrophysics Data System (ADS)
Braun, M. A.
2005-07-01
In the perturbative QCD approach single and double inclusive cross-sections for gluon production off the nucleus are studied by the relevant reggeized gluon diagrams. Various terms corresponding to emission of gluons from the triple pomeron vertex are found. Among them the term derived by Kovchegov and Tuchin emerges as a result of the transition from the diffractive to effective high-energy vertex. However it does not exhaust all the vertex contributions to the inclusive cross-section. In the double inclusive cross-section a contribution violating the naive AGK rules is found in which one gluon is emitted from the vertex and the other from one of the two pomerons below the vertex. But then this contribution is subdominant at high energies and taking it into account seems to be questionable.
Inclusive gluon production in the dipole approach: Abramovskii-Gribov-Kancheli (AGK) cutting rules
NASA Astrophysics Data System (ADS)
Levin, Eugene; Prygarin, Alex
2008-12-01
We consider single gluon production in the dipole model and reproduce the result of Kovchegov and Tuchin for the adjoint (gluonic) dipole structure of the inclusive cross section. We show the validity of the adjoint dipole structure to any order of evolution by deriving and solving the nonlinear evolution for the nondiagonal cross section of a dipole scattering off the target. The form of the solution to this equation restores the dipole interpretation for nondiagonal cross sections that appear in gluon production. Using this formalism, we analyze the single inclusive production cross section in terms of the contributions of different multiplicities, and we derive the Abramovskii-Gribov-Kancheli (AGK) cutting rules for two-Pomeron exchange. The cutting rules, which were found in this formalism, fully reproduce the original AGK rules for the total cross section. However, for the case of gluon production, the AGK rules are violated already for one-gluon emission from the vertex.
Towards the continuum limit of the lattice Landau gauge gluon propagator
Oliveira, O.; Silva, P. J.
2011-05-23
The infrared behaviour of the lattice Landau gauge gluon propagator is discussed, combining results from simulations with different volumes and lattice spacings. In particular, the Cucchieri-Mendes bounds are computed and their implications for D(0) discussed.
Measurement of the Gluon Polarization {delta}g/g from Open Charm at COMPASS
Kunne, Fabienne
2009-08-04
We have measured the gluon polarization in the nucleon by detecting charm production via D{sup 0} meson decay to charged K and {pi} in polarized muon scattering off a longitudinally polarized deuteron target. The dominant process for charm production is the photon gluon fusion into a charm anti-charm quark pair. By using all deuteron statistics from COMPASS accumulated between 2002 and 2006, we extract double spin asymmetries in bins of the transverse momentum and the energy of the D{sup 0} meson and we perform a leading order analysis of the data to extract the gluon polarization <{delta}g/g> = -0.49{+-}0.27(stat){+-}0.11(syst) at a Quantum Chromodynamics (QCD) scale {mu}{sup 2} = 13 GeV{sup 2} and at a gluon momentum fraction
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.
Multivacuum states in a fermionic gap equation with massive gluons and confinement
NASA Astrophysics Data System (ADS)
Capdevilla, R. M.
2015-04-01
We study the nontrivial solutions of the Quantum Chromodynamics (QCD) fermionic gap equation (FGE) including the contribution of dynamically massive gluons and the confining propagator proposed by Cornwall. Without the confining propagator, in the case of nonrunning gluon mass (mg), we found the multivacuum solutions (replicas) reported in the literature and we were able to define limits on mg for dynamical chiral symmetry breaking (CSB). On the other side, when considering the running in the gluon mass the vacuum replicas are absent in the limits on mg where the chiral symmetry is broken. In the pure confining sector, the multivacuum states are always absent so it is said that only one stable solution for the gap equation is found as claimed in previous analysis using different approaches. Finally, in the case of the complete gap equation i.e. with both contributions, the vacuum replicas are also absent in both cases; with constant and with running gluon mass.
Deconfined phase of QCD and thermodynamics of the quark-gluon plasma
NASA Astrophysics Data System (ADS)
Levkova, Ludmila
2012-03-01
The quark-gluon plasma is a state of matter which forms at very high temperatures or densities. It is believed that up to microseconds after the big bang the quark-gluon plasma was a dominant component of the Universe. This state of matter is recreated in heavy-ion collision experiments (such as RHIC and ALICE) which study its formation and transition to ordinary matter. Knowledge of the properties of the quark-gluon plasma is essential to our understanding of the particle spectra produced in these experiments, and also for phenomena related to cosmology and compact star formation. I present recent results for the thermodynamics of the quark-gluon plasma from lattice QCD, which is the only nonperturbative method currently allowing its first principle determination.
Thermalization of mini-jets in a quark-gluon plasma
NASA Astrophysics Data System (ADS)
Iancu, Edmond; Wu, Bin
2016-03-01
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.
Semirelativistic potential model for low-lying three-gluon glueballs
Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard
2006-09-01
The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Low-lying J{sup PC} states are computed and compared with recent lattice calculations. A good agreement is found for 1{sup --} and 3{sup --} states, but our model predicts a 2{sup --} state much higher in energy than the lattice result. The 0{sup -+} mass is also computed.
NASA Astrophysics Data System (ADS)
Cucchieri, A.; Dudal, D.; Mendes, T.; Vandersickel, N.
2012-05-01
We present an analytic description of numerical results for the Landau-gauge SU(2) gluon propagator D(p2), obtained from lattice simulations (in the scaling region) for the largest lattice sizes to date, in d=2, 3 and 4 space-time dimensions. Fits to the gluon data in 3d and in 4d show very good agreement with the tree-level prediction of the refined Gribov-Zwanziger (RGZ) framework, supporting a massive behavior for D(p2) in the infrared limit. In particular, we investigate the propagator’s pole structure and provide estimates of the dynamical mass scales that can be associated with dimension-two condensates in the theory. In the 2d case, fitting the data requires a noninteger power of the momentum p in the numerator of the expression for D(p2). In this case, an infinite-volume-limit extrapolation gives D(0)=0. Our analysis suggests that this result is related to a particular symmetry in the complex-pole structure of the propagator and not to purely imaginary poles, as would be expected in the original Gribov-Zwanziger scenario.
Measurement of the Gluon Contribution to the Nucleon Spin at COMPASS
Dedek, N.
2005-10-26
The measurement of the gluon contribution to the nucleon spin {delta}G is one of the main goals of the COMPASS experiment located at the CERN Super Proton Synchrotron. The key reaction is the photon gluon fusion to D (D-bar) -mesons. The status of the analysis of the D0- and D*-events is shown as well as the expected statistical error of {delta}G/G from the first 3 years of data taking.
Gluon propagators in maximally Abelian gauge in SU(3) lattice QCD
NASA Astrophysics Data System (ADS)
Gongyo, Shinya; Suganuma, Hideo
2013-04-01
In SU(3) lattice QCD, we study diagonal and off-diagonal gluon propagators in the maximally Abelian gauge with U(1)3×U(1)8 Landau gauge fixing. These propagators are studied both in the coordinate space and in the momentum space. The Monte Carlo simulation is performed on 164 at β=6.0 and 324 at β=5.8 and 6.0 at the quenched level. In the four-dimensional Euclidean space-time, the effective mass of diagonal gluons is estimated as Mdiag≃0.3GeV and that of off-diagonal gluons as Moff≃1GeV in the region of r=0.4-1.0fm. In the momentum space, the effective mass of diagonal gluons is estimated as Mdiag≃0.3GeV and that of off-diagonal gluons as Moff≃1GeV in the region of p<1.1GeV. The off-diagonal gluon propagator is relatively suppressed in the infrared region and seems to be finite at zero momentum, while the diagonal gluon propagator is enhanced. Furthermore, we also study the functional form of these propagators in momentum space. These propagators are well fitted by Z/(p2+m2)ν with fit parameters, Z, m, and ν in the region of p<3.0GeV. From the fit results and lattice calculations, all of the spectral functions of diagonal and off-diagonal gluons would have negative regions.
J/{Psi} suppression as an evidence for quark gluon matter
Kharzeev, D.
1998-08-10
The J/{psi} suppression was originally proposed as a signature of the quark-gluon plasma. Strong suppression of J/{psi} production was indeed observed recently by the NA50 Collaboration at CERN SPS. Is it the first signature of a long-awaited quark-gluon matter, or just a peculiar combination of ''conventional'' effects acting together to produce the puzzling pattern observed experimentally? In this lecture, I am trying to summarize the existing theoretical explanations.
Non-perturbative effects for the Quark-Gluon Plasma equation of state
Begun, V. V. Gorenstein, M. I. Mogilevsky, O. A.
2012-07-15
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.
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.
Interference contributions to gluon initiated heavy Higgs production in the two-Higgs-doublet model
NASA Astrophysics Data System (ADS)
Greiner, Nicolas; Liebler, Stefan; Weiglein, Georg
2016-03-01
We discuss the production of a heavy neutral Higgs boson of a {CP}-conserving two-Higgs-doublet model in gluon fusion and its decay into a four-fermion final state, gg (→ VV) &r^+e^-μ ^+μ ^-/e^+e^-ν _lbar{ν }_l. We investigate the interference contributions to invariant mass distributions of the four-fermion final state and other relevant kinematical observables. The relative importance of the different contributions is quantified for the process in the on-shell approximation, gg→ ZZ. We show that interferences of the heavy Higgs with the light Higgs boson and background contributions are essential for a correct description of the differential cross section. Even though they contribute below {{O}}(10 %) to those heavy Higgs signal cross sections, to which the experiments at the Large Hadron Collider were sensitive in its first run, we find that they are sizable in certain regions of the parameter space that are relevant for future heavy Higgs boson searches. In fact, the interference contributions can significantly enhance the experimental sensitivity to the heavy Higgs boson.
Gluon versus photon production of a 750 GeV diphoton resonance
NASA Astrophysics Data System (ADS)
Csáki, Csaba; Hubisz, Jay; Lombardo, Salvator; Terning, John
2016-05-01
The production mechanism of a 750 GeV diphoton resonance, either via gluon or photon fusion, can be probed by studying kinematic observables in the diphoton events. We perform a detector study of the two production modes of a hypothetical scalar or tensor diphoton resonance in order to characterize the features of the two scenarios. The nature of the resonance production can be determined from the jet multiplicity, the jet and diphoton rapidities, the rate of central pseudorapidity gaps, or the possible detection of forward protons from elastic photoproduction for events in the signal region. Kinematic distributions for both signals and expected irreducible diphoton background events are provided for comparison along with a study of observables useful for distinguishing the two scenarios at an integrated luminosity of 20 fb-1 . We find that decay photons from a 750 GeV scalar resonance have a preference for acceptance in the central detector barrel, while background events are more likely to give accepted photons in the detector end caps. This disfavors the interpretation of the large number of excess events found by the Run-2 CMS diphoton search with one photon detected in the end cap as a wide spin-0 resonance signal. However, one expects more end cap photons in the case of spin-2 resonance.
Experimental study of collective motion in the quark gluon plasma
NASA Astrophysics Data System (ADS)
Esumi, Shinichi
2008-04-01
Collective phenomena have been studied to investigate a property of Quark Gluon Plasma in high-energy heavy-ion collisions at AGS, SPS and RHIC experiments. Whether the origin of elliptic and/or radial collective expansions is given in a partonic or a hadronic phase during the collisons is a key question for the experimetal observables to be sensitive to the QGP or not. The number of quark scaling in the observed elliptic flow parameter v2 is one of intuitive evidences for the existence of the quark phase before the hadronization. The radial and elliptic flow of heavy quarks would also favour the strong interacting plasma phase. The modification of the near- and away-side jet shape and its relation to the elliptic anisotropy could prove the property of the matter in the phase. Experimental measurements especially on the collective motion of the high density and temperature matter created in high-enegy heavy-ion collisions will be presented and discussed.
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.
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
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.
Linear polarization of gluons and photons in unpolarized collider experiments
Pisano, Cristian; Boer, Daniël; Brodsky, Stanley J.; Buffing, Maarten G. A.; Mulders, Piet J.
2013-10-01
We study azimuthal asymmetries in heavy quark pair production in unpolarized electron-proton and proton-proton collisions, where the asymmetries originate from the linear polarization of gluons inside unpolarized hadrons. We provide cross section expressions and study the maximal asymmetries allowed by positivity, for both charm and bottom quark pair production. The upper bounds on the asymmetries are shown to be very large depending on the transverse momentum of the heavy quarks, which is promising especially for their measurements at a possible future Electron-Ion Collider or a Large Hadron electron Collider. We also study the analogous processes and asymmetries in muon pair production as a means to probe linearly polarized photons inside unpolarized protons. For increasing invariant mass of the muon pair the asymmetries become very similar to the heavy quark pair ones. Finally, we discuss the process dependence of the results that arises due to differences in color flow and address the problem with factorization in case of proton-proton collisions.
Hydrodynamic transport coefficients for the non-conformal quark-gluon plasma from holography
NASA Astrophysics Data System (ADS)
Finazzo, Stefano I.; Rougemont, Romulo; Marrochio, Hugo; Noronha, Jorge
2015-02-01
In this paper we obtain holographic formulas for the transport coefficients κ and τ π present in the second-order derivative expansion of relativistic hydrodynamics in curved spacetime associated with a non-conformal strongly coupled plasma described holographically by an Einstein+Scalar action in the bulk. We compute these coefficients as functions of the temperature in a bottom-up non-conformal model that is tuned to reproduce lattice QCD thermodynamics at zero baryon chemical potential. We directly compute, besides the speed of sound, 6 other transport coefficients that appear at second-order in the derivative expansion. We also give an estimate for the temperature dependence of 11 other transport coefficients taking into account the simplest contribution from non-conformal effects that appear near the QCD crossover phase transition. Using these results, we construct an Israel-Stewart-like theory in flat spacetime containing 13 of these 17 transport coefficients that should be suitable for phenomenological applications in the context of numerical hydrodynamic simulations of the strongly-coupled, non-conformal quark-gluon plasma. Using several different approximations, we give parametrizations for the temperature dependence of all the second-order transport coefficients that appear in this theory in a format that can be easily implemented in existing numerical hydrodynamic codes.
Suppression of Baryon Diffusion and Transport in a Baryon Rich Strongly Coupled Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Rougemont, Romulo; Noronha, Jorge; Noronha-Hostler, Jacquelyn
2015-11-01
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 ≤μB≤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.
Heavy quark diffusion with relativistic Langevin dynamics in the quark-gluon fluid
Akamatsu, Yukinao; Hatsuda, Tetsuo; Hirano, Tetsufumi
2009-05-15
The relativistic diffusion process of heavy quarks is formulated on the basis of the relativistic Langevin equation in Ito discretization scheme. The drag force inside the quark-gluon plasma (QGP) is parametrized according to the formula for the strongly coupled plasma obtained by the anti-de-Sitter space/conformal field theory (AdS/CFT) correspondence. The diffusion dynamics of charm and bottom quarks in QGP is described by combining the Langevin simulation under the background matter described by the relativistic hydrodynamics. Theoretical calculations of the nuclear modification factor R{sub AA} and the elliptic flow v{sub 2} for the single electrons from the charm and bottom decays are compared with the experimental data from the relativistic heavy-ion collisions. The R{sub AA} for electrons with large transverse momentum (p{sub T}>3 GeV) indicates that the drag force from the QGP is as strong as the AdS/CFT prediction.
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. PMID:26613433
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
NASA Astrophysics Data System (ADS)
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.
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. PMID:27419563
Production of semi-quark-gluon-monopole plasma by glasma decay
NASA Astrophysics Data System (ADS)
Iwazaki, Aiichi
2016-05-01
Using the standard Lagrangian of gluons and a model of dual superconductor for magnetic monopoles, I calculate the number densities of the gluons and monopoles produced by the decay of background color electric E and magnetic B fields (glasma). It turns out that gluons are dominant decay products when the initial values of the gauge fields are large such that g E =g B >(0.5GeV) 2 , while they are suppressed and monopoles are dominant decay products when the initial values are small such that g E =g B <(0.4GeV) 2 . The feature of the gluon dominance at large g E =g B and the monopole dominance at small g E =g B is similar to that of thermalized quark gluon monopole plasmas proposed recently, if one identifies √{g E }=√{g B } as temperatures of the plasmas. The identification is suggested by the fact that the energy densities of the gluons and monopoles are proportional to the initial values (gB ) 2=(gE ) 2 , while the energy densities of the plasmas are proportional to T4. The feature of the gluon dominance in the glasmas with large saturation momenta was derived in classical statistical field theories, while the feature of the monopole dominance was not yet derived. Although the model of the monopoles is phenomenological, my analysis suggests that the monopoles play important roles in the decay of the glasmas with small saturation momenta, to which classical statistical field theories are not applicable.
Nuclear parton distribution functions and their uncertainties
Hirai, M.; Kumano, S.; Nagai, T.-H.
2004-10-01
We analyze experimental data of nuclear structure-function ratios F{sub 2}{sup A}/F{sub 2}{sup A{sup '}} and Drell-Yan cross section ratios for obtaining optimum parton distribution functions (PDFs) in nuclei. Then, uncertainties of the nuclear PDFs are estimated by the Hessian method. Valence-quark distributions are determined by the F{sub 2} data at large x; however, the small-x part is not obvious from the data. On the other hand, the antiquark distributions are determined well at x{approx}0.01 from the F{sub 2} data and at x{approx}0.1 by the Drell-Yan data; however, the large-x behavior is not clear. Gluon distributions cannot be fixed by the present data and they have large uncertainties in the whole x region. Parametrization results are shown in comparison with the data. We provide a useful code for calculating nuclear PDFs at given x and Q{sup 2}.
Light-quark two-loop corrections to heavy-quark pair production in the gluon fusion channel
NASA Astrophysics Data System (ADS)
Bonciani, R.; Ferroglia, A.; Gehrmann, T.; von Manteuffel, A.; Studerus, C.
2013-12-01
We calculate the two-loop corrections to heavy-quark pair production in the gluon fusion channel which arise from diagrams involving a closed light-quark loop. The calculation is carried out by keeping the exact dependence on the heavy-quark mass. The analytic results are written in terms of logarithms, classical polylogarithms Li n ( n = 2 , 3 , 4), and genuine multiple polylogarithms Li2,2. The functional arguments are rational expressions of two independent external invariants and they are chosen in such a way that the functions are real in all the physical phase-space points. Through systematic changes in the functional basis, we obtain expansions of the results in both the production threshold and small mass limits.
Dilepton production by dynamical quasi-particles in the strongly interacting quark-gluon plasma
NASA Astrophysics Data System (ADS)
Linnyk, O.
2011-02-01
We address the dilepton production by the constituents of the strongly interacting quark-gluon plasma (sQGP). In order to make quantitative predictions for dilepton rates at experimentally relevant low dilepton mass (O(1GeV)) and strong coupling (αS ~ 0.5-1), we take into account non-perturbative spectral functions and self-energies of the quarks, antiquarks and gluons. For this purpose, we use parametrizations of the quark and gluon propagators provided by the dynamical quasi-particle model (DQPM) matched to reproduce lattice quantum chromodynamics (QCD) data. The DQPM describes QCD properties in terms of the single-particle Green's functions and leads to the notion of the constituents of the sQGP being effective quasi-particles, which are massive and have broad spectral functions (due to large interaction rates). By 'dressing' the quark and gluon lines with the effective propagators, we derive the off-shell cross sections for dilepton production in the reactions q+\\,\\bar{q}\\rightarrow l^+l^- (Born mechanism), q+ \\,\\bar{q}\\rightarrow g+\\,l^+l^- (quark annihilation with the gluon bremsstrahlung in the final state), q(\\bar{q})+g\\rightarrow q(\\bar{q})+ l^+l^- (gluon-Compton scattering), g\\rightarrow q+\\bar{q}+l^+l^- and q(\\bar{q})\\rightarrow q(\\bar{q})+g+l^+l^- (virtual gluon decay, virtual quark decay). In contrast to previous calculations of these cross sections, we account for virtualities of all the quarks and gluons. We find that finite masses of the effective quasi-particles not only screen the singularities typical of the perturbative cross sections with massless quarks, but also modify the shape of the dilepton production cross sections, especially at low dilepton mass Q and at the edges of the phase space. Finally, we use the calculated mass-dependent cross sections to identify the dependence of the dilepton rates on the spectral function widths of the initial and final quarks and gluons, which has not been estimated so far. The results
Intrinsic Glue Distribution at Very Small x
NASA Astrophysics Data System (ADS)
Jalilian-Marian, Jamal
1996-10-01
Gluon distribution function is computed at small x in large nuclei. By using RG methods McLerran-Venugopalan model is extended and a Lipatov like enhancement as well as a non-trivial transverse momentum dependence is generated . It is shown how the problem of unitarity may be resolved in lepton-nucleus interactions.
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.
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
First study of the three-gluon static potential in lattice QCD
NASA Astrophysics Data System (ADS)
Cardoso, M.; Bicudo, P.
2008-10-01
We estimate the potential energy for a system of three static gluons in lattice QCD. This is relevant for the different models of three-body glueballs that have been proposed in the literature, either for gluons with a constituent mass, or for massless ones. A Wilson loop adequate to the static hybrid three-body system is developed. We study different spacial geometries, to compare the starfish model with the triangle model, for the three-gluon potential. We also study two different color structures, symmetric and antisymmetric, and compare the respective static potentials. A first simulation is performed in a 243×48 periodic Lattice, with β=6.2 and ã0.072fm.
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}.
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
Probing the Anomalous Couplings of the Top Quark with Gluon at the Lhc and Tevatron
NASA Astrophysics Data System (ADS)
Hesari, Hoda; Najafabadi, Mojtaba Mohammadi
2013-11-01
In this paper, we study the sensitivity of the fraction of t\\bar {t} events arising from gluon-gluon fusion to the chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) as well as the total and differential t\\bar {t} cross-sections at the LHC and Tevatron. The sensitivity of measured charged asymmetry at the LHC to CEDM and CMDM is also studied. We find that at the Tevatron and the LHC, nonzero values of CMDM could suppress the t\\bar {t} production rate. It is shown that the ratio of σ (gg-> t\\bar {t})/σ (p\\bar {p}-> t\\bar {t}) at the Tevatron is more sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always increases the contribution of gluon-gluon fusion process in top pair rate at the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM and CMDM can increase the fraction of gluon-gluon fusion at the Tevatron and LHC. The measured ratio of σ (gg-> t\\bar {t})/σ (p\\bar {p}-> t\\bar {t}) at the Tevatron is used to derive bounds on the chromoelectric and chromomagnetic dipole moments as well as the total and differential (dσ /dmt\\bar {t}) cross-sections at the LHC and Tevatron, and the measured charged asymmetry at the LHC. The combination of dσ TeV/dmt\\bar {t} and σLHC provides stringent limits on CMDM and CEDM.
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.
Model independent determination of the gluon condensate in four dimensional SU(3) gauge theory.
Bali, Gunnar S; Bauer, Clemens; Pineda, Antonio
2014-08-29
We determine the nonperturbative gluon condensate of four-dimensional SU(3) gauge theory in a model-independent way. This is achieved by carefully subtracting high-order perturbation theory results from nonperturbative lattice QCD determinations of the average plaquette. No indications of dimension-two condensates are found. The value of the gluon condensate turns out to be of a similar size as the intrinsic ambiguity inherent to its definition. We also determine the binding energy of a B meson in the heavy quark mass limit. PMID:25215978
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.
Role of gluons and the quark sea in the proton spin
NASA Astrophysics Data System (ADS)
Zavada, Petr
2015-12-01
The real, interacting elementary particle always consists of a 'bare' particle and a cloud of virtual particles mediating a self-interaction and/or the bond inside a composite object. In this letter we discuss the question of spin content of the virtual cloud in two different cases: electron and quark. Further, the quark spin is discussed in the context of proton spin, which is generated by the interplay of quarks and virtual gluons. We present a general constraint on the gluon contribution and make a comparison with the experimental data.
NASA Astrophysics Data System (ADS)
Snyder, Douglas
2014-03-01
For a pair of entangled signal idler photons, one may ``lose'' the idler photon that carries which-way information and provides which-way information to the entangled signal photon before the signal photon is detected, thereby losing the entanglement. Over a number of runs, the result is an overall non-ww distribution of the signal photons. If instead the idler photon is not lost, the idler photon continues to supply ww information to the signal photon and over a number of runs the result is an overall ww distribution of the signal photons. These different overall distributions of signal photons do not depend on correlating detections of the entangled paired signal idler photons. The experiment allows for a delayed choice on the idler photons to determine the distribution of distant signal photons (either overall ww or overall not ww) without having to make correlations between signal and idler photon detections.
Energy loss, equilibration, and thermodynamics of a baryon rich strongly coupled quark-gluon plasma
NASA Astrophysics Data System (ADS)
Rougemont, Romulo; Ficnar, Andrej; Finazzo, Stefano I.; Noronha, Jorge
2016-04-01
Lattice data for the QCD equation of state and the baryon susceptibility near the crossover phase transition (at zero baryon density) are used to determine the input parameters of a 5-dimensional Einstein-Maxwell-Dilaton holographic model that provides a consistent holographic framework to study both equilibrium and out-of-equilibrium properties of a hot and baryon rich strongly coupled quark-gluon plasma (QGP). We compare our holographic equation of state computed at nonzero baryon chemical potential, μ B , with recent lattice calculations and find quantitative agreement for the pressure and the speed of sound for μ B ≤ 400 MeV. This holographic model is used to obtain holographic predictions for the temperature and μ B dependence of the drag force and the Langevin diffusion coefficients associated with heavy quark jet propagation as well as the jet quenching parameter q and the shooting string energy loss of light quarks in the baryon dense plasma. We find that the energy loss of heavy and light quarks generally displays a nontrivial, fast-varying behavior as a function of the temperature near the crossover. Moreover, energy loss is also found to generally increase due to nonzero baryon density effects even though this strongly coupled liquid cannot be described in terms of well defined quasiparticle excitations. Furthermore, to get a glimpse of how thermalization occurs in a hot and baryon dense QGP, we study how the lowest quasinormal mode of an external massless scalar disturbance in the bulk is affected by a nonzero baryon charge. We find that the equilibration time associated with the lowest quasinormal mode decreases in a dense medium.
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
Parton and valon distributions in the nucleon
Hwa, R.C.; Sajjad Zahir, M.
1981-06-01
Structure functions of the nucleon are analyzed in the valon model in which a nucleon is assumed to be a bound state of three valence quark clusters (valons). At high Q/sup 2/ the structure of the valons is described by leading-order results in the perturbative quantum chromodynamics. From the experimental data on deep-inelastic scattering off protons and neutrons, the flavor-dependent valon distributions in the nucleon are determined. Predictions for the parton distributions are then made for high Q/sup 2/ without guesses concerning the quark and gluon distributions at low Q/sup 2/. The sea-quark and gluon distributions are found to have a sharp peak at very small x. Convenient parametrization is provided which interpolates between different numbers of flavors.
Aguilar, A. C.; Papavassiliou, J.; Binosi, D.
2008-07-15
We show that the application of a novel gauge-invariant truncation scheme to the Schwinger-Dyson equations of QCD leads, in the Landau gauge, to an infrared finite gluon propagator and a divergent ghost propagator, in qualitative agreement 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.
A New Phase of Matter: Quark-Gluon Plasma Beyond the Hagedorn Critical Temperature
NASA Astrophysics Data System (ADS)
Müller, Berndt
I retrace the developments from Hagedorn's concept of a limiting temperature for hadronic matter to the discovery and characterization of the quark-gluon plasma as a new state of matter. My recollections begin with the transformation more than 30 years ago of Hagedorn's original concept into its modern interpretation as the "critical" temperature separating the hadron gas and quark-gluon plasma phases of strongly interacting matter. This was followed by the realization that the QCD phase transformation could be studied experimentally in high-energy nuclear collisions. I describe here my personal effort to help develop the strangeness experimental signatures of quark and gluon deconfinement and recall how the experimental program proceeded soon to investigate this idea, at first at the SPS, then at RHIC, and finally at LHC. As is often the case, the experiment finds more than theory predicts, and I highlight the discovery of the "perfectly" liquid quark-gluon plasma at RHIC. I conclude with an outline of future opportunities, especially the search for a critical point in the QCD phase diagram.
Effective degrees of freedom and gluon condensation in the high temperature deconfined phase
Castorina, P.; Mannarelli, M.
2007-05-15
The equation of state and the properties of matter in the high temperature deconfined phase are analyzed by a quasiparticle approach for T>1.2T{sub c}. In order to fix the parameters of our model we employ the lattice QCD data of energy density and pressure. First we consider the pure SU(3) gluon plasma and it turns out that such a system can be described in terms of a gluon condensate and of gluonic quasiparticles whose effective number of degrees of freedom and mass decrease with increasing temperature. Then we analyze QCD with finite quark masses. In this case the numerical lattice data for energy density and pressure can be fitted assuming that the system consists of a mixture of gluon quasiparticles, fermion quasiparticles, boson correlated pairs (corresponding to in-medium mesonic states) and gluon condensate. We find that the effective number of boson degrees of freedom and the in-medium fermion masses decrease with increasing temperature. At T{approx_equal}1.5T{sub c} only the correlated pairs corresponding to the mesonic nonet survive and they completely disappear at T{approx_equal}2T{sub c}. The temperature dependence of the velocity of sound of the various quasiparticles, the effects of the breaking of conformal invariance and the thermodynamic consistency are discussed in detail.
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.
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.
Probing Sea Quarks and Gluons: The Electron-Ion Collider Project
NASA Astrophysics Data System (ADS)
Horn, Tanja
2014-03-01
The 21st century holds great promise for reaching a new era for unlocking the mysteries of the structure of the atomic nucleus and the nucleons inside it governed by the theory of strong interactions (QCD). In particular, much remains to be learned about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons. One of the main goals of existing and nearly completed facilities is to map out the spin flavor structure of the nucleons in the valence region. A future Electron-Ion Collider (EIC) would be the world's first polarized electron-proton collider, and the world's first e-A collider, and would seek the QCD foundation of nucleons and nuclei in terms of the sea quarks and gluons, matching to these valence quark studies. The EIC will provide a versatile range of kinematics and beam polarization, as well as beam species, to allow for mapping the spin and spatial structure of the quark sea and gluons, to discover the collective effects of gluons in atomic nuclei, and to understand the emergence of hadronic matter from color charge.
NCG gluon fusion for the Higgs production at large hadron colliders
Chadou, I.; Mebarki, N.; Bekli, M. R.
2012-06-27
A pure NCG gluon fusion contribution to the Higgs production at large hadron colliders is discussed. It is shown that the NCG results become relevant at very high energies. This can be a good signal for the space-time non commutativity events.
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.
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
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss
2007-03-01
We propose a new approach to the problem of 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-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. 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 LHC.
Inclusive hadron distributions in p+p collisions from saturation models of HERA DIS data.
Tribedy, P.; Venugopalan, R.
2010-12-06
Dipole models based on various saturation scenarios provide reasonable fits to small-x DIS inclusive, diffractive and exclusive data from HERA. Proton un-integrated gluon distributions extracted from such fits are employed in a k{sub {perpendicular}}-factorization framework to calculate inclusive gluon distributions at various energies. The n-particle multiplicity distribution predicted in the Glasma flux tube approach shows good agreement with data over a wide range of energies. Hadron inclusive transverse momentum distributions expressed in terms of the saturation scale demonstrate universal behavior over a wider kinematic range systematically with increasing center of mass energies.
NASA Astrophysics Data System (ADS)
Thilker, David A.; Vinsen, K.; Galaxy Properties Key Project, PS1
2014-01-01
To measure resolved galactic physical properties unbiased by the mask of recent star formation and dust features, we are conducting a citizen-scientist enabled nearby galaxy survey based on the unprecedented optical (g,r,i,z,y) imaging from Pan-STARRS1 (PS1). The PS1 Optical Galaxy Survey (POGS) covers 3π steradians (75% of the sky), about twice the footprint of SDSS. Whenever possible we also incorporate ancillary multi-wavelength image data from the ultraviolet (GALEX) and infrared (WISE, Spitzer) spectral regimes. For each cataloged nearby galaxy with a reliable redshift estimate of z < 0.05 - 0.1 (dependent on donated CPU power), publicly-distributed computing is being harnessed to enable pixel-by-pixel spectral energy distribution (SED) fitting, which in turn provides maps of key physical parameters such as the local stellar mass surface density, crude star formation history, and dust attenuation. With pixel SED fitting output we will then constrain parametric models of galaxy structure in a more meaningful way than ordinarily achieved. In particular, we will fit multi-component (e.g. bulge, bar, disk) galaxy models directly to the distribution of stellar mass rather than surface brightness in a single band, which is often locally biased. We will also compute non-parametric measures of morphology such as concentration, asymmetry using the POGS stellar mass and SFR surface density images. We anticipate studying how galactic substructures evolve by comparing our results with simulations and against more distant imaging surveys, some of which which will also be processed in the POGS pipeline. The reliance of our survey on citizen-scientist volunteers provides a world-wide opportunity for education. We developed an interactive interface which highlights the science being produced by each volunteer’s own CPU cycles. The POGS project has already proven popular amongst the public, attracting about 5000 volunteers with nearly 12,000 participating computers, and is
Dudal, D.; Vandersickel, N.; Verschelde, H.; Sorella, S. P.
2008-04-01
So far, the infrared behavior of the gluon and ghost propagator based on the Gribov-Zwanziger approach predicted a positivity violating gluon propagator vanishing at zero momentum, and an infrared enhanced ghost propagator. However, recent data based on huge lattices have revealed a positivity violating gluon propagator which turns out to attain a finite nonvanishing value very close to zero momentum. At the same time the ghost propagator does not seem to be infrared enhanced anymore. We point out that these new features can be accounted for by yet unexploited dynamical effects within the Gribov-Zwanziger approach, leading to an infrared behavior in qualitatively good agreement with the new data.
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)
Surrow, Bernd
2014-01-01
The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions at √ {s} = 200 GeV and √ {s} = 500 GeV to gain a deeper insight into the spin structure and dynamics of the proton. One of the main objectives of the spin physics program at RHIC is the precise determination of the polarized gluon distribution function. The STAR detector is well suited for the reconstruction of various final states involving jets, π0, π±, e± and γ, which allows to measure several different processes. Recent results suggest a gluon spin contribution to the proton spin at the same level as the quark spin contribution itself. The production of W bosons in polarized p+p collisions at √ {s} = 500 GeV opens a new era in the study of the spin-flavor structure of the proton. W-(+) bosons are produced in \\bar {u} + d (\\bar {d} + u) collisions and can be detected through their leptonic decays, e- + \\bar {ν }e (e++ν e), where only the respective charged lepton is measured. Results of W-(+) production suggest a large asymmetry between the polarization of anti-u and anti-d quarks.
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
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.
Gluon saturation and inclusive hadron production at LHC
Levin, Eugene; Rezaeian, Amir H.
2010-07-01
In high-density QCD the hadron production stems from decay of mini jets that have the transverse momenta of the order of the saturation scale. It is shown in this paper that this idea is able to describe in a unique fashion both the inclusive hadron production for {radical}(s){>=}546 GeV including the first data from LHC and the deep inelastic scattering at HERA. Recently reported data from ALICE, CMS, and ATLAS including inclusive charged-hadron transverse momentum and multiplicity distribution in pp collisions are well described in our approach. We provide predictions for the upcoming LHC measurements.
Physics of hot hadronic matter and quark-gluon plasma
Shuryak, E.V.
1990-07-01
This Introductory talk contains a brief review of the current status of theoretical and experimental activities related to physics of superdense matter. In particular, we discuss latest lattice results on the phase transition, recent progress in chiral symmetry physics based on the theory of interacting instantons, new in the theory of QGP and of hot hadronic matter, mean p{sub t} and collective flow, the shape of p{sub t} distribution, strangeness production, J/{psi} suppression and {phi} enhancement, two puzzles connected with soft pion and soft photon enhancements, and some other ultrasoft'' phenomena. 56 refs., 6 figs.
Thermal charm and charmonium production in quark gluon plasma
NASA Astrophysics Data System (ADS)
Zhou, Kai; Chen, Zhengyu; Greiner, Carsten; Zhuang, Pengfei
2016-07-01
We study the effect of thermal charm production on charmonium regeneration in high energy nuclear collisions. By solving the kinetic equations for charm quark and charmonium distributions in Pb+Pb collisions, we calculate the global and differential nuclear modification factors RAA (Npart) and RAA (pt) for J / ψ s. Due to the thermal charm production in hot medium, the charmonium production source changes from the initially created charm quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future Circular Collider (FCC), and the J / ψ suppression (RAA < 1) observed so far will be replaced by a strong enhancement (RAA > 1) at FCC at low transverse momentum.
Gluon scattering in N = 4 Super Yang-Mills at finite temperature
Ito, Katsushi; Iwasaki, Koh; Nastase, Horatiu
2008-11-23
We extend the AdS/CFT prescription of Alday and Maldacena to finite temperature T, defining an amplitude for gluon scattering in N = 4 Super Yang-Mills at strong coupling from string theory. It is defined by a lightlike 'Wilson loop' living at the horizon of the T-dual to the black hole in AdS space. Unlike the zero temperature case, this is different from the Wilson loop contour defined at the boundary of the AdS black hole metric, thus at nonzero T there is no relation between gluon scattering amplitudes and the Wilson loop. We calculate a gauge theory observable that can be interpreted as the amplitude at strong coupling in both cut-off and generalized dimensional regularization.
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.
Jet Quenching Phenomenology from Soft-Collinear Effective Theory with Glauber Gluons
NASA Astrophysics Data System (ADS)
Kang, Zhong-Bo; Lashof-Regas, Robin; Ovanesyan, Grigory; Saad, Philip; Vitev, Ivan
2015-03-01
We present the first application of a recently developed effective theory of jet propagation in matter, soft-collinear effective theory with Glauber gluons (SCETG ), to inclusive hadron suppression in nucleus-nucleus collisions at RHIC and the LHC. SCETG-based splitting kernels allow us to go beyond the traditional energy loss approximation and unify the treatment of vacuum and medium-induced parton showers. In the soft gluon emission limit, we establish a simple analytic relation between the QCD evolution and energy loss approaches to jet quenching. We quantify the uncertainties associated with the implementation of the in-medim modification of hadron production cross sections and show that the coupling between the jet and the medium can be constrained with better than 10% accuracy.
{lambda}{sub c} Enhancement from Strongly Coupled Quark-Gluon Plasma
Lee, Su Houng; Ohnishi, Kazuaki; Yasui, Shigehiro; Yoo, In-Kwon; Ko, Che Ming
2008-06-06
We propose the enhancement of {lambda}{sub c} as a novel quark-gluon plasma signal in heavy ion collisions at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider. Assuming a stable bound diquark state in the strongly coupled quark-gluon plasma near the critical temperature, we argue that the direct two-body collision between a c quark and a [ud] diquark would lead to an enhanced {lambda}{sub c} production in comparison with the normal three-body collision among independent c, u, and d quarks. In the coalescence model, we find that the {lambda}{sub c}/D yield ratio is enhanced substantially due to the diquark correlation.
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 GoSAM and SHERPA. We present numerical resultsmore » for a large variety of observables for both standard cuts and VBF selection cuts.« less
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)
Quark-gluon soup — The perfectly liquid phase of QCD
NASA Astrophysics Data System (ADS)
Heinz, Ulrich
2015-01-01
At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.
Gluon saturation and energy dependence of hadron multiplicity in pp and AA collisions at the LHC
Levin, Eugene; Rezaeian, Amir H.
2011-06-01
The recent results in {radical}(s)=2.76 TeV Pb+Pb collisions at the Large Hadron Collider (LHC) reported by the ALICE collaboration shows that the power-law energy-dependence of charged hadron multiplicity in Pb+Pb collisions is significantly different from p+p collisions. We show that this different energy-dependence can be explained by inclusion of a strong angular-ordering in the gluon-decay cascade within the color glass condensate (or gluon saturation) approach. This effect is more important in nucleus-nucleus collisions where the saturation scale is larger than 1 GeV. Our prescription gives a good description of the LHC data both in p+p and Pb+Pb collisions.
Higgs Boson Production via Gluon Fusion in the Standard Model with four Generations
Li Qiang; Spira, Michael; Gao, Jun; Li Chongsheng
2011-05-01
Higgs bosons can be produced copiously at the LHC via gluon fusion induced by top and bottom quark loops, and can be enhanced strongly if extra heavy quarks exist. We present results for Higgs+zero-, one- and two-jet production at the LHC operating at 7 and 14 TeV collision energy, in both the standard model and the 4th generation model, by evaluating the corresponding heavy quark triangle, box, and pentagon Feynman diagrams. We compare the results by using the effective Higgs-gluon interactions in the limit of heavy quarks with the cross sections including the full mass dependences. NLO effects on Higgs+zero-jet production rate with full mass dependence are presented for the first time consistently in the 4th generation model. Our results improve the theoretical basis for fourth generation effects on the Higgs boson search at the LHC.
Energy change of a heavy quark in a viscous quark-gluon plasma with fluctuations
NASA Astrophysics Data System (ADS)
Jiang, Bing-feng; Hou, De-fu; Li, Jia-rong
2016-09-01
When a heavy quark travels through the quark-gluon plasma, the polarization and fluctuating chromoelectric fields will be produced simultaneously in the plasma. The drag force due to those fields exerting in return on the moving heavy quark will cause energy change to it. Based on the dielectric functions derived from the viscous chromohydrodynamics, we have studied the collisional energy change of a heavy quark traversing the viscous quark-gluon plasma including fluctuations of chromoelectric field. Numerical results indicate that the chromoelectric field fluctuations lead to an energy gain of the moving heavy quark. Shear viscosity suppresses the fluctuation-induced energy gain and the viscous suppression effect for the charm quark is much more remarkable than that for the bottom quark. While, the fluctuation energy gain is much smaller than the polarization energy loss in magnitude and the net energy change for the heavy quark is at loss.
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
2015-06-09
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.
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.
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.
Jet quenching phenomenology from soft-collinear effective theory with Glauber gluons.
Kang, Zhong-Bo; Lashof-Regas, Robin; Ovanesyan, Grigory; Saad, Philip; Vitev, Ivan
2015-03-01
We present the first application of a recently developed effective theory of jet propagation in matter, soft-collinear effective theory with Glauber gluons (SCET_{G}), to inclusive hadron suppression in nucleus-nucleus collisions at RHIC and the LHC. SCET_{G}-based splitting kernels allow us to go beyond the traditional energy loss approximation and unify the treatment of vacuum and medium-induced parton showers. In the soft gluon emission limit, we establish a simple analytic relation between the QCD evolution and energy loss approaches to jet quenching. We quantify the uncertainties associated with the implementation of the in-medim modification of hadron production cross sections and show that the coupling between the jet and the medium can be constrained with better than 10% accuracy. PMID:25793803
Gluon propagator in Feynman gauge by the method of stationary variance
NASA Astrophysics Data System (ADS)
Siringo, Fabio
2014-11-01
The low-energy limit of pure Yang-Mills S U (3 ) gauge theory is studied in Feynman gauge by the method of stationary variance, a genuine second-order variational method that is suited to deal with the minimal coupling of fermions in gauge theories. In terms of standard irreducible graphs, the stationary equations are written as a set of coupled nonlinear integral equations for the gluon and ghost propagators. A physically sensible solution is found for any strength of the coupling. The gluon propagator is finite in the infrared, with a dynamical mass that decreases as a power at high energies. At variance with some recent findings in Feynman gauge, the ghost dressing function does not vanish in the infrared limit and a decoupling scenario emerges as recently reported for the Landau gauge.
Two-particle correlations in high-energy collisions and the gluon four-point function
Dumitru, Adrian; Jalilian-Marian, Jamal
2010-05-01
We derive the rapidity evolution equation for the gluon four-point function in the dilute regime and at small x from the JIMWLK functional equation. We show that beyond leading order in N{sub c} the mean field (Gaussian) approximation where the four-point function is factorized into a product of two-point functions is violated. We calculate these factorization breaking terms and show that they contribute at leading order in N{sub c} to correlations of two produced gluons as a function of their relative rapidity and azimuthal angle, for generic (rather than back-to-back) angles. Such two-particle correlations have been studied experimentally at the BNL-RHIC collider and could be scrutinized also for pp (and, in the future, also AA) collisions at the CERN-LHC accelerator.
Classical strongly coupled quark-gluon plasma. I. Model and molecular dynamics simulations
Gelman, Boris A.; Shuryak, Edward V.; Zahed, Ismail
2006-10-15
We propose a model for the description of strongly interacting quarks and gluon quasiparticles at T=(1-3)T{sub c} 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{approx_equal}0.1/T and a shear viscosity to entropy density ratio {eta}/s{approx_equal}1/3.
From quarks and gluons to hadrons: Chiral symmetry breaking in dynamical QCD
NASA Astrophysics Data System (ADS)
Braun, Jens; Fister, Leonard; Pawlowski, Jan M.; Rennecke, Fabian
2016-08-01
We present an analysis of the dynamics of two-flavor QCD in the vacuum. Special attention is paid to the transition from the high-energy quark-gluon regime to the low-energy regime governed by hadron dynamics. This is done within a functional renormalization group approach to QCD amended by dynamical hadronization techniques. These techniques allow us to describe conveniently the transition from the perturbative high-energy regime to the nonperturbative low-energy limit without suffering from a fine-tuning of model parameters. In the present work, we apply these techniques to two-flavor QCD with physical quark masses and show how the dynamics of the dominant low-energy degrees of freedom emerge from the underlying quark-gluon dynamics.
McLerran, L.
1984-11-01
The author discusses the applicability of a hydrodynamic description of high energy hadronic collisions. The author reviews the results of recent computations of the mean free paths of quarks and gluons in a quark-gluon plasma, and the corresponding results for viscous coefficients. These quantities are employed to evaluate the limits to the application of perfect fluid hydrodynamics as a description of time evolution of matter produced in various hadronic collisions. 22 references.
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.
A measurement of the gluon splitting rate into pairs in hadronic Z decays
NASA Astrophysics Data System (ADS)
ALEPH Collaboration; Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Merle, E.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Alemany, R.; Boix, G.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Graugès, E.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Park, I. C.; Pascual, A.; Riu, I.; Sanchez, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; 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.; Becker, U.; Bright-Thomas, P.; Casper, D.; Cattaneo, M.; Cerutti, F.; Ciulli, V.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Halley, A. W.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Lehraus, I.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Ranjard, F.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Teubert, F.; Tomalin, I. R.; Wachsmuth, H.; Ajaltouni, Z.; Badaud, F.; Chazelle, G.; Deschamps, O.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J.-C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Lynch, J. G.; Negus, P.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Buchmüller, O.; Dhamotharan, S.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Marinelli, N.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Buck, P. G.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Robertson, N. A.; Williams, M. I.; Giehl, I.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Carr, J.; Coyle, P.; Etienne, F.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Büscher, V.; Cowan, G.; Dietl, H.; Ganis, G.; Lütjens, G.; Mannert, C.; Männer, W.; Moser, H.-G.; Schael, S.; Settles, R.; Seywerd, H.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Boccali, T.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Konstantinidis, N.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Giannini, G.; Gobbo, B.; Musolino, G.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; Gao, Y.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A., III; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Zobernig, G.
1998-08-01
A measurement of the fraction of hadronic Z decays in which a gluon splits into a bb¯ pair, gbb¯, is presented using data collected by ALEPH from 1992 to 1995 at the Z resonance. The selection is based on four-jet events. Events are selected by means of topological cuts and a lifetime tag. The result is gbb¯=(2.77+/-0.42(stat)+/-0.57(syst))x10- 3.
Imaginary part of the static gluon propagator in an anisotropic (viscous) QCD plasma
Dumitru, Adrian; Guo, Yun; Strickland, Michael
2009-06-01
We determine viscosity corrections to the retarded, advanced and symmetric gluon self-energies and to the static propagator in the weak-coupling ''hard loop'' approximation to high-temperature QCD. We apply these results to calculate the imaginary part of the heavy-quark potential which is found to be smaller (in magnitude) than at vanishing viscosity. This implies a smaller decay width of quarkonium bound states in an anisotropic plasma.
Spectroscopy of mesons containing light quarks (u, d, s) or gluons
NASA Astrophysics Data System (ADS)
Diekmann, Bernd
1988-02-01
This paper gives an overview of the increase of experimental knowledge of mesons which are built by light quarks. This naturally includes also those mesonic states containing gluons and those with an exotic internal quark structure such as qq¯-qq¯. The resulting mesonic “zoo” will be compared with predictions from actual phenomenological ansatzes: e.g. potential models, the bag model, and QCD sum rules, and also more general approaches such as QCD lattice gauge theories.
3D imaging of sea quarks and gluons at an electron-ion collider
Vadim Guzey
2011-11-01
We outline key objectives and capabilities of an Electron-Ion Collider (EIC) — a high-energy and high-luminosity electron-proton/nucleus collider with polarized electron and proton beams. One of goals of a future EIC is to map the 3D (in configuration and momentum spaces) structure of sea quarks and gluons in the nucleon and nuclei. We briefly present and discuss key observables and measurements pertaining to the program of 3D imaging at an EIC.
Soft gluon resummations in dijet azimuthal angular correlations in hadronic collisions.
Sun, Peng; Yuan, C-P; Yuan, Feng
2014-12-01
We derive all order soft gluon resummation in dijet azimuthal angular correlation in hadronic collisions at the next-to-leading logarithmic level. The relevant coefficients for the Sudakov resummation factor, the soft and hard factors, are calculated. The theory predictions agree well with the experimental data from D0 Collaboration at the Tevatron. This provides a benchmark calculation for the transverse momentum dependent QCD resummation for jet productions in hadron collisions. PMID:25526118
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.
Cancellation of Glauber Gluon Exchange in the Double Drell-Yan Process
NASA Astrophysics Data System (ADS)
Diehl, Markus; Gaunt, Jonathan R.; Ostermeier, Daniel; Plößl, Peter; Schäfer, Andreas
2016-06-01
For any factorisation proof, a crucial step is a demonstration of the cancellation of so-called Glauber gluons. We summarise a recent paper in which we demonstrated this cancellation for double Drell-Yan production (the double parton scattering process in which a pair of electroweak gauge bosons is produced), both for the integrated cross section and for the cross section differential in the boson transverse momenta.
Insights into the Quark-Gluon Vertex from Lattice QCD and Meson Spectroscopy
NASA Astrophysics Data System (ADS)
Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.; Paracha, M. Ali.
2015-09-01
By comparing successful quark-gluon vertex interaction models with the corresponding interaction extracted from lattice-QCD data on the quark's propagator, we identify common qualitative features which could be important to tune future interaction models beyond the rainbow ladder approximation. Clearly, a quantitative comparison is conceptually not simple, but qualitatively the results suggest that a realistic interaction should be relatively broad with a strong support at about 0.4-0.6 GeV and infrared-finite.
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.
Effects of dynamical masses of gluons and quarks on hadronic B decays
Zanetti, C. M.; Natale, A. A.
2010-11-12
We study hadronic annihilation decays of B mesons within the perturbative QCD at collinear approximation. The regulation of endpoint divergences is performed with the help of an infrared finite gluon propagator characterized by a non-perturbative dynamical gluon mass. The divergences at twist-3 are regulated by a dynamical quark mass. Our results fit quite well the existent data of B{sup 0}{yields}D{sub s}{sup -}K{sup +} and B{sup 0}{yields}D{sub s}{sup -*}K{sup +} for the expected range of dynamical gluon masses. We also make predictions for the rare decays B{sup 0}{yields}K{sup -}K{sup +}, B{sub s}{sup 0}{yields}{pi}{sup -}{pi}{sup +}, {pi}{sup 0}{pi}{sup 0}, B{sup +}{yields}D{sub s}{sup (*)+}K-bar{sup 0}, B{sup 0}{yields}D{sub s}{sup {+-}(*)}K{sup {+-}} and B{sub s}{sup 0}{yields}D{sup {+-}(*)}{pi}{sup {+-}}, D{sup 0}{pi}{sup 0}.
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.
Combined study of the gluon and ghost condensates and <{epsilon}{sup abc}c{sup b}c{sup c}> in Euclidean SU(2) Yang-Mills theory in the Landau gauge
Capri, M.A.L.; Lemes, V.E.R.; Sobreiro, R.F.; Sorella, S.P.; Dudal, D.; Verschelde, H.; Gracey, J.A.
2006-01-01
The ghost condensate <{epsilon}{sup abc}c{sup b}c{sup c}> is considered together with the gluon condensate in SU(2) Euclidean Yang-Mills theories quantized in the Landau gauge. The vacuum polarization ceases to be transverse due to the nonvanishing condensate <{epsilon}{sup abc}c{sup b}c{sup c}>. The gluon propagator itself remains transverse. By polarization effects, this ghost condensate induces then a splitting in the gluon mass parameter, which is dynamically generated through . The obtained effective masses are real when is included in the analysis. In the absence of , the already known result that the ghost condensate induces effective tachyonic masses is recovered. At the one-loop level, we find that the effective diagonal mass becomes smaller than the off-diagonal one. This might serve as an indication for some kind of Abelian dominance in the Landau gauge, similar to what happens in the maximal Abelian gauge.
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
Scattering of massless particles: scalars, gluons and gravitons
NASA Astrophysics Data System (ADS)
Cachazo, Freddy; He, Song; Yuan, Ellis Ye
2014-07-01
In a recent note we presented a compact formula for the complete tree-level S-matrix of pure Yang-Mills and gravity theories in arbitrary spacetime dimension. In this paper we show that a natural formulation also exists for a massless colored cubic scalar theory. In Yang-Mills, the formula is an integral over the space of n marked points on a sphere and has as integrand two factors. The first factor is a combination of Parke-Taylor-like terms dressed with U( N ) color structures while the second is a Pfaffian. The S-matrix of a U( N ) × U( Ñ ) cubic scalar theory is obtained by simply replacing the Pfaffian with a U( Ñ ) version of the previous U( N ) factor. Given that gravity amplitudes are obtained by replacing the U( N ) factor in Yang-Mills by a second Pfaffian, we are led to a natural color-kinematics correspondence. An expansion of the integrand of the scalar theory leads to sums over trivalent graphs and are directly related to the KLT matrix. Combining this and the Yang-Mills formula we find a connection to the BCJ color-kinematics duality as well as a new proof of the BCJ doubling property that gives rise to gravity amplitudes. We end by considering a special kinematic point where the partial amplitude simply counts the number of color-ordered planar trivalent trees, which equals a Catalan number. The scattering equations simplify dramatically and are equivalent to a special Y-system with solutions related to roots of Chebyshev polynomials. The sum of the integrand over the solutions gives rise to a representation of Catalan numbers in terms of eigenvectors and eigenvalues of the adjacency matrix of an A-type Dynkin diagram.
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.
Jet-vetoed Higgs cross section in gluon fusion at N3LO+NNLL with small-R resummation
NASA Astrophysics Data System (ADS)
Banfi, Andrea; Caola, Fabrizio; Dreyer, Frédéric A.; Monni, Pier Francesco; Salam, Gavin P.; Zanderighi, Giulia; Dulat, Falko
2016-04-01
We present new results for the jet-veto efficiency and zero-jet cross section in Higgs production through gluon fusion. We incorporate the N3LO corrections to the total cross section, the NNLO corrections to the 1-jet rate, NNLL resummation for the jet p t and LL resummation for the jet radius dependence. Our results include known finite-mass corrections and are obtained using the jet-veto efficiency method, updated relative to earlier work to take into account what has been learnt from the new precision calculations that we include. For 13 TeV collisions and using our default choice for the renormalisation and factorisation scales, μ 0 = m H /2, the matched prediction for the jet-veto efficiency increases the pure N3LO prediction by about 2% and the two have comparable uncertainties. Relative to NNLO+NNLL results, the new prediction is 2% smaller and the uncertainty reduces from about 10% to a few percent. Results are also presented for the central scale μ 0 = m H .
NASA Astrophysics Data System (ADS)
Mazumder, Surasree; Alam, Jan-e.
2012-04-01
We study the effects of the equation of state on the nuclear suppression of heavy flavors in quark gluon plasma and estimate the initial entropy density of the system produced in Au + Au collision at the highest Relativistic Heavy Ion Collider (RHIC) energy. For this purpose the experimental data on the charged-particle multiplicity and the nuclear suppression of single-electron spectra originating from the semileptonic decays of open charm and beauty mesons have been employed. We have used inputs from lattice QCD to minimize the model dependence of the results. We obtain the value of the initial entropy density, which varies from 20 to 59/fm3 depending on the value of the velocity of sound that one uses for the analysis. Our investigation leads to a conservative value of the initial entropy density of ˜20/fm3 with a corresponding initial temperature of ˜210 MeV, which is well above the value of the transition temperature predicted by lattice QCD.
Perturbative and non-perturbative aspects of moments of the thrust distribution in e+e-
NASA Astrophysics Data System (ADS)
Gardi, Einan
2000-04-01
Resummation and power-corrections play a crucial role in the phenomenology of event-shape variables like the thrust T. Previous investigations showed that the perturbative contribution to the average thrust is dominated by gluons of small invariant mass, of the order of 10% of Q, where Q is the center-of-mass energy. The effect of soft gluons is also important, leading to a non-perturbative 1/Q correction. These conclusions are based on renormalon analysis in the single dressed gluon (SDG) approximation. Here we analyze higher moments of the thrust distribution using a similar technique. We find that the characteristic gluon invariant mass contributing to langle(1-T)mrangle increases with m. Yet, for m = 2 this scale is quite low, around 27% of Q, and therefore renormalon resummation is still very important. On the other hand, the power-correction to langle(1-T)2rangle from a single soft gluon emission is found to be highly suppressed: it scales as 1/Q3. In practice, langle(1-T)2rangle and higher moments depend also on soft gluon emission from configurations of three hard partons, which may lead to αs(Q2)/Q power-corrections. This issue is yet to be investigated.
The Four-loop Six-gluon NMHV Ratio Function
Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.
2015-09-29
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 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
Suppression and energy loss in Quark-Gluon Plasma
NASA Astrophysics Data System (ADS)
Djordjevic, M.
2016-01-01
High momentum suppression of light and heavy flavor observables is considered to be an excellent probe of jet-medium interactions in QCD matter created at RHIC and LHC. Utilizing this tool requires accurate suppression predictions for different experiments, probes and experimental conditions, and their unbiased comparison with experimental data. We developed the dynamical energy loss formalism which takes into account both radiative and collision energy loss computed within the same theoretical framework, dynamical (as opposed to static) scattering centers, finite magnetic mass, running coupling and uses no free parameters in comparison with experimental data. Within this formalism, we provide predictions, and a systematic comparison with the experimental data, for a diverse set of probes, various centrality ranges and various collision energies at RHIC and LHC. We also provide clear qualitative and quantitative predictions for the upcoming LHC experiments. A comprehensive agreement between our predictions and experimental results suggests that our dynamical energy loss formalism can well explain the jet-medium interactions in QGP, which will be further tested by the obtained predictions for the upcoming data.
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.
Valence-quark distribution functions in the kaon and pion
NASA Astrophysics Data System (ADS)
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-01
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.
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.
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?
NASA Astrophysics Data System (ADS)
Tannenbaum, M. J.
2015-03-01
. Thus an apparent hard scattering component for A+A multiplicity distributions based on a popular formula, dNAAch/dη = [(1 - x) langleNpartrangle dNppch/dη/2 + x langleNcollrangledNppch/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.
NASA Astrophysics Data System (ADS)
Tarasov, Yu. A.
1998-11-01
Hard π0 and η production is investigated in Landau and Bjorken hydrodynamical models taking into account great number of hadronic resonances (16 and 42) in hadronic phase. We consider two different scenario: with quark-gluon plasma (QGP) formation and with only hadronic gas one without QGP. The Cronin effect and hard direct pions emission are taken into account. It is shown that these two scenario give similar p⊥ spectra which agrees with experimental data obtained by WA80 collaboration. Therefore we conclude that from hadronic spectra it is difficult to extract the proof of QGP formation. However we calculate also the η/π0 ratio. We show that this value agrees with experiment only for scenario with QGP and phase transition to hadrons. The hadronic gas scenario without QGP disagrees with experimental data.
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 .
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.
Gluon scattering in N=4 super-Yang-Mills theory fromweak to strong coupling
Dixon, Lance J.; /SLAC
2008-03-25
I describe some recent developments in the understanding of gluon scattering amplitudes in N = 4 super-Yang-Mills theory in the large-N{sub c} limit. These amplitudes can be computed to high orders in the weak coupling expansion, and also now at strong coupling using the AdS/CFT correspondence. They hold the promise of being solvable to all orders in the gauge coupling, with the help of techniques based on integrability. They are intimately related to expectation values for polygonal Wilson loops composed of light-like segments.
Temperature dependence of dimension-6 gluon operators and their effects on charmonium
NASA Astrophysics Data System (ADS)
Kim, HyungJoo; Morita, Kenji; Lee, Su Houng
2016-01-01
Starting from an earlier representation of the independent dimension-6 gluon operators in terms of color electric and magnetic fields, we estimate their changes near the critical temperature Tc using the temperature dependence of the dimension-4 electric and magnetic condensates extracted from pure gauge theory on the lattice. We then improve the previous QCD sum rules for the J /ψ mass near Tc based on dimension-4 operators, by including the contribution of the dimension-6 operators to the OPE. We find an enhanced stability in the sum rule and confirm that the J /ψ will undergo an abrupt change in the property across Tc.
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.
Anisotropy of the semiclassical gluon field of a large nucleus at high energy
NASA Astrophysics Data System (ADS)
Dumitru, Adrian; Skokov, Vladimir
2015-04-01
The McLerran-Venugopalan model describes a highly boosted hadron/nucleus as a sheet of random color charges which source soft classical Weizsäcker-Williams gluon fields. We show that due to fluctuations, individual configurations are azimuthally anisotropic. We present initial evidence that impact parameter dependent small-x Jalilian-Marian, Iancu, McLerran, Weigert, Leonidov and Kovner (JIMWLK) resummation preserves such anisotropies over several units of rapidity. Finally, we compute the first four azimuthal Fourier amplitudes of the S-matrix of a fundamental dipole in such background fields.
The thermal width of heavy quarkonia moving in quark-gluon plasma
Wong, Cheuk-Yin; Song, Taesoo; Park, Yongjae; Lee, Su Houng
2008-01-01
The velocity dependence of the thermal width of heavy quarkonia traveling with respect to the quark-gluon plasma is calculated up to the NLO in perturbative QCD. At the LO, the width decreases with increasing speed, whereas at the NLO it increases with a magnitude approximately proportional to the expectation value of the relative velocity between the quarkonium and a parton in thermal equilibrium. Such an asymptotic behavior is due to the NLO dissociation cross section converging to a nonvanishing value in the high energy limit.
Aspects of a dynamical gluon mass approach to elastic hadron scattering at LHC
NASA Astrophysics Data System (ADS)
Fagundes, D. A.; Luna, E. G. S.; Menon, M. J.; Natale, A. A.
2012-07-01
We discuss how the main features of the recent LHC data on elastic scattering can be described by a QCD-inspired formalism with a dynamical infrared mass scale. For this purpose new developments on a dynamical gluon mass approach are reported, with emphasis on a method to estimate uncertainty bounds in the predictions for the high-energy scattering observables. We investigate the effects due to the correlations among the fixed and free parameters involved and show that the bands of predictions are consistent with the recent data from the TOTEM experiment, including the forward quantities and the differential cross section up to the dip position.
The Initial Flow of Classical Gluon Fields in Heavy Ion Collisions
NASA Astrophysics Data System (ADS)
Fries, Rainer J.; Chen, Guangyao
2015-03-01
Using analytic solutions of the Yang-Mills equations we calculate the initial flow of energy of the classical gluon field created in collisions of large nuclei at high energies. We find radial and elliptic flow which follows gradients in the initial energy density, similar to a simple hydrodynamic behavior. In addition we find a rapidity-odd transverse flow field which implies the presence of angular momentum and should lead to directed flow in final particle spectra. We trace those energy flow terms to transverse fields from the non-abelian generalization of Gauss' Law and Ampere's and Faraday's Laws.
Higgs boson gluon-fusion production beyond threshold in N3LO 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 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.
A complete two-loop, five-gluon helicity amplitude in Yang-Mills theory
NASA Astrophysics Data System (ADS)
Badger, Simon; Mogull, Gustav; Ochirov, Alexander; O'Connell, Donal
2015-10-01
We compute the integrand of the full-colour, two-loop, five-gluon scattering amplitude in pure Yang-Mills theory with all helicities positive, using generalized unitarity cuts. Tree-level BCJ relations, satisfied by amplitudes appearing in the cuts, allow us to deduce all the necessary non-planar information for the full-colour amplitude from known planar data. We present our result in terms of irreducible numerators, with colour factors derived from the multi-peripheral colour decomposition. Finally, the leading soft divergences are checked to reproduce the expected infrared behaviour.
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.
Exploring Hadron Production from Jets and Quark Gluon Plasma at LHC
NASA Astrophysics Data System (ADS)
Jinkins, Katherine
2013-10-01
QCD jets are sprays of hadrons created from a quark or gluon at high energy. Hadrons from jets dominate the hadron spectrum above transverse momenta PT ~ 5-8 GeV/c in ultra-relativistic heavy ion collisions at RHIC and LHC. At smaller momenta, below PT ~ 2 GeV/c, hadron production is well described by hydrodynamics or blast-wave models assuming thermalization, while between 2 and 5 GeV/c hadron production proceeds through quark recombination of an off-equilibrium quark gluon plasma. We improved the jet quenching code PPM to describe the high-momentum hadron data recently published by the ALICE experiment at the LHC. PPM Glauber calculations of the transverse densities of nucleons participating in collisions, and the overall number of participants and collisions (Npart and Ncoll, respectively) were updated by changing the previous hard sphere approximation of a nucleus to Woods-Saxon profiles. Impact parameters were matched to centrality bins published by the ALICE experiment. Using the sLPM (Landau-Pomeranchuk-Migdal effect) energy loss model for partons in PPM, the energy loss parameter csLPM = qhat/s was adjusted to achieve a consistent description of high momentum ALICE data. A blast wave model calculation at low momentum was also added to achieve a comprehensive fit to ALICE data. Funded by NSF REU Program.
Phenomenological analysis of Higgs boson production through gluon fusion in association with jets
Greiner, Nicolas; Höche, Stefan; Luisoni, Gionata; Schönherr, Marek; Winter, Jan -Christopher; Yundin, Valery
2016-01-27
In this study, 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. Wemore » present numerical results for a large variety of observables for both standard cuts and VBF selection cuts. We find that for all jet multiplicities the NLO corrections are sizeable. This is particularly true in the presence of kinematic selections enhancing the VBF topology, which are based on vetoing additional jet activity. In this case, precise predictions for the background can be made using our calculation by taking the difference between the inclusive H+2 jets and the inclusive H+3 jets result.« less