Topic
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: This work proposes a method to measure the double parton scattering at LHCb using leptonic final states from the decay of two prompt J/ψ mesons.
Abstract: We argue that the recent LHCb observation of J/ψ-pair production indicates a significant contribution from double parton scattering, in addition to the standard single parton scattering component. We propose a method to measure the double parton scattering at LHCb using leptonic final states from the decay of two prompt J/ψ mesons.
123 citations
TL;DR: In this paper, the authors calculate the virtuality-dependent beam function at NNLO, which is relevant for any observables probing the virtualities of the incoming partons, in-cluding N-jettiness and beam thrust.
Abstract: In dierential measurements at a hadron collider, collinear initial-state radi- ation is described by process-independent beam functions. They are theeld-theoretic analog of initial-state parton showers. Depending on the measured observable they are dierential in the virtuality and/or transverse momentum of the colliding partons in ad- dition to the usual longitudinal momentum fraction. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, in- cluding N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N 3 LL order, and provide all contribu- tions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two dierent methods to evaluate the discontinuity of the two-loop Feynman diagrams, pro- viding nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and conrm at two loops that the virtuality-dependent beam andnal-state jet functions have the same anomalous dimension.
123 citations
TL;DR: In this paper, the authors extend and improve the last-step evolution approach, and explain why doubly-unintegrated parton distributions are necessary for (z,k_t)-factorization.
Abstract: We describe how unintegrated parton distributions can be calculated from conventional integrated distributions. We extend and improve the 'last-step' evolution approach, and explain why doubly-unintegrated parton distributions are necessary. We generalise k_t-factorisation to (z,k_t)-factorisation. We apply the formalism to inclusive jet production in deep-inelastic scattering, mainly at leading-order, but we also study the extension to next-to-leading order. We compare the predictions with recent HERA data.
123 citations
TL;DR: In this article, the authors present analytic results for the complete weak corrections to gluon-induced top-quark pair production at the Tevatron and the Large Hadron Collider (LHC) at CERN.
Abstract: Top-quark physics plays an important role at hadron colliders such as the Tevatron at Fermilab or the upcoming Large Hadron Collider (LHC) at CERN. Given the planned experimental precision, detailed theoretical predictions are mandatory. In this article we present analytic results for the complete weak corrections to gluon-induced top-quark pair production – neglecting purely photonic corrections, completing our earlier results for the quark-induced reaction. As an application we discuss top-quark pair production at the Tevatron and LHC. In particular we show that, although they are small for inclusive quantities, weak corrections can be sizeable for differential distributions.
123 citations
TL;DR: In this paper, the nucleon is described as a bound state of three quarks in the p → ∞ frame, and the constituent quarks have themselves a structure suggested by the quark gluon parton model.
123 citations