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arXiv · 2403.00664

Nonperturbative Collins-Soper Kernel from Chiral Quarks with Physical Masses

Dennis Bollweg·Xiang Gao·Swagato Mukherjee·Yong Zhao
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Abstract

We present a lattice QCD calculation of the rapidity anomalous dimension of quark transverse-momentum-dependent distributions, i.e., the Collins-Soper (CS) kernel, up to transverse separations of about 1 fm. This unitary lattice calculation is conducted, for the first time, employing the chiral-symmetry-preserving domain wall fermion discretization and physical values of light and strange quark masses. The CS kernel is extracted from the ratios of pion quasi-transverse-momentum-dependent wave functions (quasi-TMDWFs) at next-to-leading logarithmic perturbative accuracy. Also for the first time, we utilize the recently proposed Coulomb-gauge-fixed quasi-TMDWF correlator without a Wilson line. We observe significantly slower signal decay with increasing quark separations compared to the established gauge-invariant method with a staple-shaped Wilson line. This enables us to determine the CS kernel at large nonperturbative transverse separations and find its near-linear dependence on the latter. Our result is consistent with the recent lattice calculation using gauge-invariant quasi-TMDWFs, and agrees with various recent phenomenological parametrizations of experimental data.

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Dennis Bollweg, Xiang Gao, Swagato Mukherjee, Yong Zhao. 2024-03-01. Nonperturbative Collins-Soper Kernel from Chiral Quarks with Physical Masses. https://doi.org/10.1016/j.physletb.2024.138617

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