Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in p→+p→ collisions at s=200 GeV

Le résumé fourni par la source

Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, ${A}_{LL}$, for ${\ensuremath{\pi}}^{0}$ and $\ensuremath{\eta}$ production in $\sqrt{s}=200\text{ }\text{ }\mathrm{GeV}$ polarized $p+p$ collisions. Comparison of the ${\ensuremath{\pi}}^{0}$ results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, $\mathrm{\ensuremath{\Delta}}G$, in the proton in the probed Bjorken $x$ range. The effect of adding the new 2009 ${\ensuremath{\pi}}^{0}$ data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit value $\mathrm{\ensuremath{\Delta}}{G}_{\text{DSSV}}^{[0.05,0.2]}=0.0{6}_{\ensuremath{-}0.15}^{+0.11}$ in the range $0.05<x<0.2$, with the uncertainty at $\mathrm{\ensuremath{\Delta}}{\ensuremath{\chi}}^{2}=9$ when considering only statistical experimental uncertainties. Shifting the PHENIX data points by their systematic uncertainty leads to a variation of the best-fit value of $\mathrm{\ensuremath{\Delta}}{G}_{\text{DSSV}}^{[0.05,0.2]}$ between 0.02 and 0.12, demonstrating the need for full treatment of the experimental systematic uncertainties in future global analyses.

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