paper

Unpolarized Quark and Gluon TMD PDFs and FFs at NLO

arXiv:2012.03256 · doi:10.1007/JHEP06(2021)115

Abstract

In this paper we calculate analytically the perturbative matching coefficients for unpolarized quark and gluon Transverse-Momentum-Dependent (TMD) Parton Distribution Functions (PDFs) and Fragmentation Functions (FFs) through Next-to-Next-to-Next-to-Leading Order (NLO) in QCD. The NLO TMD PDFs are calculated by solving a system of differential equation of Feynman and phase space integrals. The TMD FFs are obtained by analytic continuation from space-like quantities to time-like quantities, taking into account the probability interpretation of TMD PDFs and FFs properly. The coefficient functions for TMD FFs exhibit double logarithmic enhancement at small momentum fraction . We resum such logarithmic terms to the third order in the expansion of . Our results constitute important ingredients for precision determination of TMD PDFs and FFs in current and future experiments.

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