Speaker
Description
Since the first surprising results on the spin structure of the proton by the EMC experiment in the late 1980s, much progress has been made in understanding the origin of the proton spin. However, the sea quark contribution to the proton spin, for example, the polarized distributions of the strange quark(anti-quark), s($\bar{s}$), is still not well constrained by experimental data. Since the s($\bar{s}$) is expected to carry a substantial fraction of the spin of the $\Lambda$($\bar{\Lambda}$) hyperon, measurements of the longitudinal spin transfer, $D_{LL}$, and the transverse spin transfer, $D_{TT}$ of the $\Lambda$($\bar{\Lambda}$) hyperon in polarized proton-proton collisions can thus shed light ̄on the helicity and transversity distriubtions of the s($\bar{s}$) in the proton. In this talk, we will present the status of the $\Lambda$($\bar{\Lambda}$) $D_{LL}$ and $D_{TT}$ analyses using data collected at RHIC-STAR experiment in 2015, for the $\Lambda$($\bar{\Lambda}$) hyperon of pseudo-rapidity |$\eta$| < 1.2 and transverse momenta up to 8.0 GeV/c. This dataset is about twice as large as that used for the previously published $D_{LL}$ and $D_{TT}$ results.
