Improved measurement of the longitudinal spin transfer to Λ and Λ¯ hyperons in polarized proton-proton collisions at s=200 GeV

Le résumé fourni par la source

The longitudinal spin transfer ${D}_{LL}$ to $\mathrm{\ensuremath{\Lambda}}$ and $\overline{\mathrm{\ensuremath{\Lambda}}}$ hyperons produced in high-energy polarized proton-proton collisions is expected to be sensitive to the helicity distribution functions of strange quarks and antiquarks of the proton, and to longitudinally polarized fragmentation functions. We report an improved measurement of ${D}_{LL}$ from data obtained at a center-of-mass energy of $\sqrt{s}=200\text{ }\text{ }\mathrm{GeV}$ with the STAR detector at RHIC. The data have an approximately twelve times larger figure of merit than prior results and cover $|\ensuremath{\eta}|<1.2$ in pseudorapidity with transverse momenta ${p}_{T}$ up to $6\text{ }\text{ }\mathrm{GeV}/c$. In the forward scattering hemisphere at largest ${p}_{T}$, the longitudinal spin transfer is found to be ${D}_{LL}=\ensuremath{-}0.036\ifmmode\pm\else\textpm\fi{}0.048(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.013(\mathrm{sys})$ for $\mathrm{\ensuremath{\Lambda}}$ hyperons and ${D}_{LL}=0.032\ifmmode\pm\else\textpm\fi{}0.043(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.013(\mathrm{sys})$ for $\overline{\mathrm{\ensuremath{\Lambda}}}$ antihyperons. The dependences on $\ensuremath{\eta}$ and ${p}_{T}$ are presented and compared with model evaluations.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.