Speaker
Description
Jets recoiling against a $Z^{0}$ or $W^{\pm}$ boson acquire longitudinal polarization owing to the parity-violating nature of the weak interaction. Weak-boson-tagged processes therefore provide a unique opportunity to study the hadronization and medium modification of polarized partons without requiring polarized incoming beams. In this work, we calculate the longitudinal polarization of $\Lambda$ hyperons produced inside $Z^{0}/W^{\pm}$-tagged jets in pp collisions, where the polarization is governed by the spin-dependent fragmentation function $G_{1L}$. We then extend the calculation to nucleus-nucleus collisions and investigate how jet-medium interactions and parton energy loss modify the observed $\Lambda$ polarization. Our results show that the $\Lambda$ polarization is sensitive to the energy loss of jets. Weak-boson-tagged $\Lambda$ production thus offers a promising probe of spin-dependent hadronization and polarized jet-medium interactions in the quark-gluon plasma.
Reference:W. H. Yao, X. Li, H. Dong and S. Y. Wei, Phys.Rev.D 113 (2026) 7, 074014.
