Determination of the Collins-Soper Kernel from Lattice QCD

Maximilian Schlemmer; Alexey Vladimirov; Christian Zimmermann; Michael Engelhardt; Andreas Schäfer

doi:10.1007/JHEP08(2021)004

paper

Determination of the Collins-Soper Kernel from Lattice QCD

arXiv:2103.16991 · doi:10.1007/JHEP08(2021)004

Abstract

We present lattice results for the non-perturbative Collins-Soper (CS) kernel, which describes the energy-dependence of transverse momentum-dependent parton distributions (TMDs). The CS kernel is extracted from the ratios of first Mellin moments of quasi-TMDs evaluated at different nucleon momenta.The analysis is done with dynamical $N_{f} = 2 + 1$ clover fermions for the CLS ensemble H101 ( $a = 0.0854 fm$ , $m_{π} = m_{K} = 422 MeV$ ). The computed CS kernel is in good agreement with experimental extractions and previous lattice studies.