Measurement of the longitudinal spin asymmetries for weak boson production in proton-proton collisions at s=510 GeV

Le résumé fourni par la source

We report new STAR measurements of the single-spin asymmetries ${A}_{L}$ for ${W}^{+}$ and ${W}^{\ensuremath{-}}$ bosons produced in polarized proton-proton collisions at $\sqrt{s}=510\text{ }\text{ }\mathrm{GeV}$ as a function of the decay-positron and decay-electron pseudorapidity. The data were obtained in 2013 and correspond to an integrated luminosity of $250\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. The results are combined with previous results obtained with $86\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. A comparison with theoretical expectations based on polarized lepton-nucleon deep-inelastic scattering and prior polarized proton-proton data suggests a difference between the $\overline{u}$ and $\overline{d}$ quark helicity distributions for $0.05<x<0.25$. In addition, we report new results for the double-spin asymmetries ${A}_{LL}$ for ${W}^{\ifmmode\pm\else\textpm\fi{}}$, as well as ${A}_{L}$ for $Z/{\ensuremath{\gamma}}^{*}$ production and subsequent decay into electron-positron pairs.

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