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arXiv · 2606.19221

The Collins-Soper kernel from a vacuum soft function

Anthony Francis·C. -J. David Lin·Wayne Morris·Yong Zhao
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Abstract

The Collins-Soper kernel is calculated from a vacuum soft function using space-like Wilson lines with complex-directional vectors on the Euclidean lattice. Our pure gauge calculations with this method achieve high statistical precision in computing the soft function, whose rapidity dependence is well described by Collins-Soper evolution across a wide range of rapidity differences. The extracted kernel contains errors comparable to those achieved in state-of-the-art lattice calculations based on hadronic observables, but exhibits saturated behavior at large transverse Wilson-line separations.

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Anthony Francis, C. -J. David Lin, Wayne Morris, Yong Zhao. 2026-06-17. The Collins-Soper kernel from a vacuum soft function. https://arxiv.org/abs/2606.19221

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