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arXiv · 2302.06502

Universality of the Collins-Soper kernel in lattice calculations

Hai-Tao Shu·Maximilian Schlemmer·Tobias Sizmann·Alexey Vladimirov·Lisa Walter·Michael Engelhardt·Andreas Schäfer·Yi-Bo Yang
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Abstract

The Collins-Soper (CS) kernel is a nonperturbative function that characterizes the rapidity evolution of transverse-momentum-dependent parton distribution functions (TMDPDFs) and wave functions. In this Letter, we calculate the CS kernel for pion and proton targets and for quasi-TMDPDFs of leading and next-to-leading power. The calculations are carried out on the CLS ensemble H101 with dynamical $N_f=2+1$ clover-improved Wilson fermions. Our analyses demonstrate the consistency of different lattice extractions of the CS kernel for mesons and baryons, as well as for twist-two and twist-three operators, even though lattice artifacts could be significant. This consistency corroborates the universality of the lattice-determined CS kernel and suggests that a high-precision determination of it is in reach.

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Hai-Tao Shu, Maximilian Schlemmer, Tobias Sizmann, Alexey Vladimirov, Lisa Walter, Michael Engelhardt, Andreas Schäfer, Yi-Bo Yang. 2023-02-13. Universality of the Collins-Soper kernel in lattice calculations. https://arxiv.org/abs/2302.06502

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