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

The longitudinal spin transfer, $D_{LL}$, from high energy polarized protons to $\mathrm{\Lambda }$ and $\bar{\mathrm{\Lambda }}$ hyperons has been measured for the first time in proton-proton collisions at $\sqrt{s}=200\mathrm{G}\mathrm{e}\mathrm{V}$ with the STAR detector at RHIC. The measurements cover pseudorapidity, $\eta$, in the range $\mathrm{\mid }\eta \mathrm{\mid }<1.2$ and transverse momenta, $p_{\mathrm{T}}$, up to $4 $\mathrm{G}\mathrm{e}\mathrm{V}$/c$\mathrm{.}Thelongitudinalspintransferisfoundtobe$D_{LL}= -0.03\pm 0.13($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}$) \pm 0.04($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}$)$forinclusive$\Lambda$and$D_{LL} = -0.12 \pm 0.08($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}$) \pm 0.03($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}$)$ for inclusive $\bar{\mathrm{\Lambda }}$ hyperons with $<\eta >=0.5$ and $<p_$\mathrm{T}$> = 3.7 $\mathrm{G}\mathrm{e}\mathrm{V}$/c$\mathrm{.}Thedependenceon$\eta$and$p_$\mathrm{T}$$ is presented.