Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in p → + p → collisions at s =200GeV
Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, ALL, for π0 and η production in s=200GeV polarized p+p collisions. Comparison of the π0 results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, ΔG, in the proton in the probed Bjorken x range. The effect of adding the new 2009 π0 data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit value ΔGDSSV[0.05,0.2]=0.06-0.15+0.11 in the range 0.05<0.2, with the uncertainty at Δχ2=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 ΔGDSSV[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. © 2014 American Physical Society.
Adare, A; Aidala, C; Ajitanand, NN; Akiba, Y; Akimoto, R; Al-Ta'Ani, H; Alexander, J; Andrews, KR; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Aschenauer, EC; Awes, TC; Azmoun, B; Babintsev, V; Bai, M; Bannier, B; Barish, KN; Bassalleck, B; Basye, AT; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belmont, R; Ben-Benjamin, J; Bennett, R; Blau, DS; Bok, JS; Boyle, K; Brooks, ML; Broxmeyer, D; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Castera, P; Chen, CH; Chi, CY; Chiu, M; Choi, IJ; Choi, JB; Choudhury, RK; Christiansen, P; Chujo, T; Chvala, O; Cianciolo, V; Citron, Z; Cole, BA; Conesa Del Valle, Z; Connors, M; Csanád, M; Csörgo, T; Dairaku, S; Datta, A; David, G; Dayananda, MK; Denisov, A; Deshpande, A; Desmond, EJ; Dharmawardane, KV; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, KA; Durham, JM; Durum, A; D'Orazio, L; Efremenko, YV; Engelmore, T; Enokizono, A; En'Yo, H; Esumi, S; Fadem, B; Fields, DE; Finger, M; Fleuret, F; Fokin, SL; Frantz, JE; Franz, A; Frawley, AD; Fukao, Y; Fusayasu, T; Gal, C; Garishvili, I; Giordano, F; Glenn, A; Gong, X; Gonin, M; Goto, Y; Granier De Cassagnac, R; Grau, N; Greene, SV
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