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Parton
About: Parton is a research topic. Over the lifetime, 13484 publications have been published within this topic receiving 368877 citations.
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TL;DR: In this paper, a linearized Boltzmann transport model coupled with hydrodynamical background is established to describe the evolution of jet shower partons and medium excitations in high energy heavy-ion collisions.
Abstract: A linearized Boltzmann transport (LBT) model coupled with hydrodynamical background is established to describe the evolution of jet shower partons and medium excitations in high energy heavy-ion collisions. We extend the LBT model to include both elastic and inelastic processes for light and heavy partons in the quark-gluon plasma. A hybrid model of fragmentation and coalescence is developed for the hadronization of heavy quarks. Within this framework, we investigate how heavy flavor observables depend on various ingredients, such as different energy loss and hadronization mechanisms, the momentum and temperature dependences of the transport coefficients, and the radial flow of the expanding fireball. Our model calculations show good descriptions of the D meson suppression and elliptic flow observed at the Larege Hadron Collider and the Relativistic Heavy-Ion Collider. The prediction for the Pb-Pb collisions at sNN=5.02 TeV is provided.
191 citations
TL;DR: The two universal functions that completely specify the structure of three-parton correlations in the soft anomalous-dimension matrix at two-loop order in closed analytic form are calculated and found to be suppressed like O(m(4)/s(2)) in the limit of small parton masses, in accordance with mass factorization theorems.
Abstract: We provide a complete description of the two-loop infrared singularities of scattering amplitudes with an arbitrary number of massive and massless partons in non-Abelian gauge theories. To this end, we calculate the two universal functions that completely specify the structure of three-parton correlations in the soft anomalous-dimension matrix at two-loop order in closed analytic form. Both functions are found to be suppressed like O(m{sup 4}/s{sup 2}) in the limit of small parton masses, in accordance with mass factorization theorems. On the other hand, they are unsuppressed near the threshold for pair production of two heavy particles. As an application, we calculate the two-loop anomalous-dimension matrix for qq->tt near threshold and show that it is not diagonal in the s-channel singlet-octet basis.
190 citations
TL;DR: In this paper, the structure of infrared and ultraviolet singularities in on-shell QCD and supersymmetric QCD amplitudes at one-loop order is discussed and the dependence on the regularization scheme is also considered.
190 citations
TL;DR: In this article, the parton distribution functions from lattice QCD were evaluated using twisted mass fermions with a pion mass of about 370 MeV and the effect of gauge link smearing in the operator to estimate the influence of the Wilson line renormalization.
Abstract: We report on our exploratory study for the direct evaluation of the parton distribution functions from lattice QCD, based on a recently proposed new approach. We present encouraging results using ${N}_{f}=2+1+1$ twisted mass fermions with a pion mass of about 370 MeV. The focus of this work is a detailed description of the computation, including the lattice calculation, the matching to an infinite momentum and the nucleon mass correction. In addition, we test the effect of gauge link smearing in the operator to estimate the influence of the Wilson line renormalization, which is yet to be done.
190 citations
TL;DR: In this article, the LHC proton-proton collisions at √s=7'TeV, corresponding to 5.0'fb-1 of integrated luminosity, have been collected with the CMS detector.
Abstract: Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC proton-proton collisions at √s=7 TeV, corresponding to 5.0 fb-1 of integrated luminosity, have been collected with the CMS detector. Jets are reconstructed up to rapidity 2.5, transverse momentum 2 TeV, and dijet invariant mass 5 TeV, using the anti-kT clustering algorithm with distance parameter R=0.7. The measured cross sections are corrected for detector effects and compared to perturbative QCD predictions at next-to-leading order, using five sets of parton distribution functions.
189 citations