Longitudinal Spin Transfer to $\Lambda$ and $\bar\Lambda$ Hyperons Produced in Polarized Proton-Proton Collisions at $\sqrt{s} = 200$ GeV

The longitudinal spin transfer, $D_{LL}$, of $\Lambda$ and $\bar\Lambda$ hyperons in longitudinally polarized proton-proton collisions is sensitive to strange quark and anti-quark polarization in the polarized proton as well as to polarized fragmentation. The STAR collaboration previously published $D_{LL}$ from a data sample obtained in 2005 that corresponds to an integrated luminosity of 2 $pb^{-1}$ with 50\% beam polarization. The $D_{LL}$ results from the data were compared to the $D_{LL}$ model calculations. A considerably larger data sample corresponding to 25 $pb^{-1}$ with beam polarization of 57\% was obtained in 2009 using an upgraded instrument. The analysis of these data is in progress and is anticipated to considerably improve the precision of the $D_{LL}$ measurements. The status of the analysis will be discussed.