Longitudinal double-spin asymmetries for π0s in the forward direction for 510 GeV polarized pp collisions

Le résumé fourni par la source

The STAR Collaboration reports measurements of the longitudinal double-spin asymmetry, ${A}_{LL}$, for neutral pions produced at forward directions in polarized proton-proton collisions, at a center-of-mass energy of 510 GeV. Results are given for transverse momenta in the range $2<{p}_{T}<10\text{ }\text{ }\mathrm{GeV}/c$ within two regions of pseudorapidity that span $2.65<\ensuremath{\eta}<3.9$. These results are sensitive to the polarized gluon parton distribution function, $\mathrm{\ensuremath{\Delta}}g(x)$, down to the region of Bjorken $x\ensuremath{\sim}{10}^{\ensuremath{-}3}$. The asymmetries observed are less than $\ifmmode\pm\else\textpm\fi{}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ in magnitude and will help constrain the contribution to the spin of the proton from polarized gluons at low $x$, when combined with other measurements as part of a global analysis.

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