Collins-Soper kernel and reduced soft function in lattice QCD

Physical review. D/Physical review. D. 2026 Open access

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Authors: Constantia Alexandrou, Simone Bacchio, Krzysztof Cichy, Martha Constantinou, Aniket Sen, Gregoris Spanoudes, Fernanda Steffens, Jacopo Tarello
DOI: 10.1103/5wft-9rtd
Cited by: 2
References: 85

Abstract

We evaluate the Collins-Soper kernel and the reduced soft function in lattice QCD, incorporating O ( α s ) matching corrections. The calculation relies on the evaluation of the quasitransverse momentum–dependent wave function with asymmetric staple-shaped quark bilinear operators and four-point meson form factors. These quantities are computed nonperturbatively using two N f = 2 + 1 + 1 twisted-mass fermion ensembles with the same lattice spacing of a = 0.093 fm : the first ensemble has a lattice size of 24 3 × 48 and a pion mass of 346 MeV, and the second one has a lattice size of 32 3 × 64 and a pion mass of 261 MeV. The Collins-Soper kernel and the soft function are needed for the determination of the transverse momentum–dependent parton distribution functions.

Fields of Study & Subjects

Quantum Chromodynamics and Particle Interactions High-Energy Particle Collisions Research Theoretical and Computational Physics

Publication details

Journal / source
Physical review. D/Physical review. D.
Publisher
American Physical Society (APS)
Volume
113
Issue
7
Publication date
19 March 2026
Language
EN