Speaker
Description
Transverse $\Lambda$ polarization in hadron-hadron and hadron-nucleus collision has been observed for over fifty years, yet its origin remains poorly understood. The fragmentation process, characterized by polarizing fragmentation functions (pFFs), has been proposed as a potential origin of this phenomenon. This mechanism can be probed via measurements of the $\Lambda$ polarization within jets. We report the measurements of the transverse polarization of $\Lambda$ and $\overline{\Lambda}$ hyperons relative to the jet axis in $p+p$ collisions at $\sqrt{s}=200$ GeV and 510 GeV, as well as in $p+Au$ collisions at $\sqrt{s_{NN}}=200$ GeV. Our results indicate that the transverse polarization of $\Lambda$ hyperons can provide a probe of the jet energy scale dependence. Furthermore, comparisons between $p+p$ and $p+Au$ collisions can provide sensitivity to possible nuclear medium effects. These findings provide a critical test of the universality of pFFs and new insights into the mechanisms responsible for transverse $\Lambda$ polarization.
