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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, the authors point out that like-sign W pair production provides a relatively clean way of searching for, and calibrating, double parton scattering at the LHC.
95 citations
TL;DR: In this paper, a Monte Carlo simulation of the perturbative quantum chromodynamics shower developing after a hard process embedded in a heavy-ion collision is presented, where the main assumption is that the cascade of branching partons traverses a medium that is characterized by a local transport coefficient that measures the virtuality per unit length transferred to a parton that propagates in this medium.
Abstract: We present a Monte Carlo simulation of the perturbative quantum chromodynamics shower developing after a hard process embedded in a heavy-ion collision. The main assumption is that the cascade of branching partons traverses a medium that (consistent with standard radiative energy loss pictures) is characterized by a local transport coefficient $\stackrel{^}{q}$ that measures the virtuality per unit length transferred to a parton that propagates in this medium. This increase in parton virtuality alters the development of the shower and in essence leads to extra induced radiation and hence a softening of the momentum distribution in the shower. After hadronization, this leads to the concept of a medium-modified fragmentation function. On the level of observables, this is manifest as the suppression of high-transverse-momentum (${P}_{T}$) hadron spectra. We simulate the soft medium created in heavy-ion collisions by a 3D hydrodynamical evolution and average the medium-modified fragmentation function over this evolution to compare with data on single inclusive hadron suppression and extract the $\stackrel{^}{q}$ that characterizes the medium. Finally, we discuss possible uncertainties of the model formulation and argue that the data in a soft momentum show evidence of qualitatively different physics that presumably cannot be described by a medium-modified parton shower.
95 citations
TL;DR: In this article, a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks is presented, where all calculations are performed in NNLO QCD with the help of a fully differential partonic Monte Carlo and are exact at this order in perturbation theory.
Abstract: We present a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks. All calculations are performed in NNLO QCD with the help of a fully differential partonic Monte-Carlo and are exact at this order in perturbation theory. We present predictions for all kinematic distributions for which data exists. Particular attention is paid on the top-quark forward-backward asymmetry which we study in detail. We compare the NNLO results with existing approximate NNLO predictions as well as differential distributions computed with different parton distribution sets. Theory errors are significantly smaller than current experimental ones with overall agreement between theory and data.
95 citations
TL;DR: In this article, the results of two-loop calculations of the O( α s 2 ) corrections to the first nonsinglet moments of the deep inelastic scattering structure functions for polarized and unpolarized targets are presented.
95 citations
TL;DR: KaTie as discussed by the authors is a parton-level event generator for hadron scattering processes that can deal with partonic initial-state momenta with an explicit transverse momentum dependence causing them to be space-like.
95 citations