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↑p collisions at s=510 GeV. The energy-scaled distribution of jet transverse momentum, xT=2pT,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↑p 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.

Energy Independence of the Collins Asymmetry in Collisions

S. Fazio;
2025-01-01

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↑p collisions at s=510 GeV. The energy-scaled distribution of jet transverse momentum, xT=2pT,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↑p 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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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/400285
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