Speaker
Description
The fragmentation process has been proposed as a possible origin of the transverse $\Lambda$ polarization, described by polarizing fragmentation functions (pFFs). In $pp$ collisions, this mechanism can be studied by measuring the $\Lambda$ polarization within jets. We present the first measurement of the transverse polarization of $\Lambda$/$\overline{\Lambda}$ hyperons relative to the jet axis in unpolarized $pp$ collisions at $\sqrt{s}=200$ GeV, using high-statistics data from the STAR experiment. The dependence of the $\Lambda$ polarization on the jet transverse momentum ($p_T^{\text{jet}}$) is observed. The polarization is also studied as a function of the jet momentum fraction ($z$) carried by the $\Lambda$/$\overline{\Lambda}$, and the $\Lambda$/$\overline{\Lambda}$ momentum transverse to the jet axis ($j_T$). These results will provide the first constraints on the gluon pFFs. These results also provide an opportunity to test the transverse momentum-dependent (TMD) evolution effect and its universality for pFFs.
