Longitudinal Spin Transfer to $Lambda$ and $arLambda$ Hyperons in Polarized Proton-Proton Collisions at $sqrts$ = 200 GeV

Abstract

The longitudinal spin transfer, $D_{LL}$, from high energy polarized protons to $Lambda$ and $bar{Lambda}$ hyperons has been measured for the first time in proton-proton collisions at $sqrt{s} = 200 mathrm{GeV}$ with the STAR detector at RHIC. The measurements cover pseudorapidity, $eta$, in the range $|eta| < 1.2$ and transverse momenta, $p_mathrm{T}$, up to $4 mathrm{GeV}/c$. The longitudinal spin transfer is found to be $D_{LL}= -0.03pm 0.13(mathrm{stat}) pm 0.04(mathrm{syst})$ for inclusive $Lambda$ and $D_{LL} = -0.12 pm 0.08(mathrm{stat}) pm 0.03(mathrm{syst})$ for inclusive $bar{Lambda}$ hyperons with $ = 0.5$ and $ = 3.7 mathrm{GeV}/c$. The dependence on $eta$ and $p_mathrm{T}$ is presented.