Energy Independence of the Collins Asymmetry in p^\uparrowp Collisions

2025/07/22 by STAR Collaboration, Aboona, B. E., The STAR Collaboration +98 · 1 citation
Engineering · Physics and Astronomy · #Space Satellite Systems and Control #Astro and Planetary Science

paper · pdf · doi:10.48550/arxiv.2507.16355

Abstract

The STAR experiment reports new, high-precision measurements of the transverse single-spin asymmetries for π^± within jets, namely the Collins asymmetries, from transversely polarized p^\uparrowp collisions at √(s) = 510 GeV. The energy-scaled distribution of jet transverse momentum, x_T = 2p_T,jet/√ s, shows a remarkable consistency for Collins asymmetries of π^± in jets between √(s) = 200 GeV and 510 GeV. This indicates that the Collins asymmetries are nearly energy independent with, at most, a very weak scale dependence in p^\uparrowp collisions. These results extend to high-momentum scales (Q² ≤ 3400 GeV²) and enable unique tests of evolution and universality in the transverse-momentum-dependent formalism, thus providing important constraints for the Collins fragmentation functions.

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