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

O. Chvala, V. Cianciolo, B. A. Cole, Valle, Z. Conesa Del Valle, M. Connors, M. Csanad, T. Csoergo, S. Dairaku, A. Datta, G. David, M. K. Dayananda, A. Denisov, A. Deshpande, E. J. Desmond, K. V. Dharmawardane, O. Dietzsch, A. Dion, M. Donadelli, O. Drapier, A. DreesK. A. Drees, J. M. Durham, A. Durum, L. D'Orazio, Y. V. Efremenko, T. Engelmore, A. Enokizono, H. En'yo, S. Esumi, B. Fadem, D. E. Fields, M. Finger, M., Jr. Finger, F. Fleuret, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, Y. Fukao, T. Fusayasu, C. Gal, I. Garishvili, F. Giordano, A. Glenn, X. Gong, M. Gonin, Y. Goto, Cassagnac, R. Granier de Cassagnac, N. Grau, S. V. Greene, M. Grosse Perdekamp, T. Gunji, L. Guo, H. -A. Gustafsson, J. S. Haggerty, K. I. Hahn, H. Hamagaki, J. Hamblen, R. Han, J. Hanks, C. Harper, K. Hashimoto, E. Haslum, R. Hayano, X. He, T. K. Hemmick, T. Hester, J. C. Hill, R. S. Hollis, W. Holzmann, K. Homma, B. Hong, T. Horaguchi, Y. Hori, D. Hornback, J. Huang, Song - Jeng Huang, T. Ichihara, R. Ichimiya, H. Iinuma, Y. Ikeda, K. Imai, M Inaba, Awadhesh Kumar Dubey, Mihael Makek, Alexander Milov, Deepali Sharma, Itzhak Tserruya,

Research output: Contribution to journalArticlepeer-review


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<x<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.

Original languageEnglish
Article number012007
JournalPhysical review D
Issue number1
StatePublished - 17 Jul 2014

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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