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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 article, an event generator based on a viscous hydrodynamical evolution starting from flux-tube initial conditions, which are generated in the Gribov-Regge multiple scattering framework is used to analyze the transverse momentum spectra of identified particles in $p$-Pb collisions at 502 TeV.
Abstract: Experimental transverse momentum spectra of identified particles in $p$-Pb collisions at 502 TeV show many similarities to the corresponding Pb-Pb results, the latter ones usually being interpreted in terms of hydrodynamic flow We analyze these data using epos3, an event generator based on a $3\mathrm{D}+1$ viscous hydrodynamical evolution starting from flux-tube initial conditions, which are generated in the Gribov-Regge multiple scattering framework An individual scattering is referred to as Pomeron, identified with a parton ladder, eventually showing up as flux tubes (or strings) Each parton ladder is composed of a perturbative QCD hard process, plus initial- and final-state linear parton emission Nonlinear effects are considered by using saturation scales ${Q}_{s}$, depending on the energy and the number of participants connected to the Pomeron in question We compute transverse momentum (${p}_{t}$) spectra of pions, kaons, protons, lambdas, and $\ensuremath{\Xi}$ baryons in $p$-Pb and $p$-$p$ scattering, compared to experimental data and many other models In this way we show in a quantitative fashion that $p$-Pb data (and even $p$-$p$ ones) show the typical ``flow effect'' of enhanced particle production at intermediate ${p}_{t}$ values, more and more visible with increasing hadron mass

187 citations

Journal ArticleDOI
TL;DR: In this paper, the authors propose to extract PDFs from QCD global analysis of "data" generated by lattice QCD calculations of good "lattice cross sections", which are basically single-hadron matrix elements that are computable and perturbative QCD factorizable into the PDFs.
Abstract: Parton distribution functions (PDFs) are nonperturbative quantities describing the relation between a hadron and the quarks and gluons within it. We propose to extract PDFs from QCD global analysis of “data” generated by lattice QCD calculations of good “lattice cross sections,” which are basically single-hadron matrix elements that are lattice QCD calculable and perturbative QCD factorizable into the PDFs. To demonstrate the existence of good “lattice cross sections,” we take quasiquark distribution introduced by Ji [Phys. Rev. Lett. 110, 262002 (2013)PRLTAO0031-900710.1103/PhysRevLett.110.262002] as a case study to show that it could be factorized into the PDFs to all orders in perturbation theory if it can be multiplicatively renormalized. We calculate the factorized coefficients at the next-to-leading order in αs.

187 citations

Journal ArticleDOI
TL;DR: In this paper, a general formulation of a Variable-flavor Number Scheme (VFNS) for heavy quarks is presented, which is explicitly implemented up to NNLO in the strong coupling constant.
Abstract: At NNLO it is particularly important to have a Variable-flavor Number Scheme (VFNS) to deal with heavy quarks because there are major problems with both the zero-mass variable-flavor number scheme and the fixed-flavor number scheme. I illustrate these problems and present a general formulation of a Variable-flavor Number Scheme (VFNS) for heavy quarks that is explicitly implemented up to NNLO in the strong coupling constant ${\ensuremath{\alpha}}_{S}$, and may be used in NNLO global fits for parton distributions. The procedure combines elements of the ACOT($\ensuremath{\chi}$) scheme and the Thorne-Roberts scheme. Despite the fact that at NNLO the parton distributions are discontinuous as one changes the number of active quark flavors, all physical quantities are continuous at flavor transitions and the comparison with data is successful.

187 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed recursive equations that could be used to generate a lowest order parton shower for hard scattering in hadron-hadron collisions, based on factorization soft and collinear interactions from relatively harder interactions in QCD amplitudes.
Abstract: We specify recursive equations that could be used to generate a lowest order parton shower for hard scattering in hadron-hadron collisions. The formalism is based on the factorization soft and collinear interactions from relatively harder interactions in QCD amplitudes. It incorporates quantum interference between different amplitudes in those cases in which the interference diagrams have leading soft or collinear singularities. It incorporates the color and spin information carried by partons emerging from a hard interaction. One motivation for this work is to have a method that can naturally cooperate with next-to-leading order calculations.

186 citations

Journal ArticleDOI
TL;DR: While the nondipole three-loop term does not vanish in two-particle collinear limits, its contribution to the splitting amplitude anomalous dimension reduces to a constant, and it depends only on the color charges of the collinEAR pair, thereby preserving strict collinears factorization properties.
Abstract: We present the three-loop result for the soft anomalous dimension governing long-distance singularities of multileg gauge-theory scattering amplitudes of massless partons. We compute all contributing webs involving semi-infinite Wilson lines at three loops and obtain the complete three-loop correction to the dipole formula. We find that nondipole corrections appear already for three colored partons, where the correction is a constant without kinematic dependence. Kinematic dependence appears only through conformally invariant cross ratios for four colored partons or more, and the result can be expressed in terms of single-valued harmonic polylogarithms of weight five. While the nondipole three-loop term does not vanish in two-particle collinear limits, its contribution to the splitting amplitude anomalous dimension reduces to a constant, and it depends only on the color charges of the collinear pair, thereby preserving strict collinear factorization properties. Finally, we verify that our result is consistent with expectations from the Regge limit.

185 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023384
2022897
2021410
2020423
2019472
2018424