Transverse spin polarization as a novel probe of medium-induced transverse-momentum-broadening effect

2025/04/01 by Qin, Xin-yu, Song, Yu-Kun, Wei, Shu-yi
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th)

paper · doi:10.48550/arxiv.2504.00739

Abstract

The transverse polarization of Λ hyperons within unpolarized jets originates from the transverse-momentum-dependent (TMD) fragmentation function D_1T^⊥ (z, p_T, μ²). In the vacuum environment, the QCD evolution of this TMD fragmentation function is governed by the Collins-Soper equation. However, in the presence of the quark-gluon plasma (QGP) medium, the jet-medium interaction induces a transverse-momentum-broadening effect that modifies the QCD evolution. As a result, the transverse spin polarization of Λ hyperons in relativistic heavy-ion collisions differs from that in pp collisions. We demonstrate that this difference serves as a sensitive probe for studying jet-medium interaction, offering a novel perspective through the spin degree of freedom.

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