Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both low...

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Veröffentlicht in:Physical review. D 2007, Vol.76
Hauptverfasser: Adare, A., Afanasiev, S., Aidala, C., Ajitanand, N.N., Akiba, Y., Al-Bataineh, H., Alexander, J., Aoki, K., Aphecetche, Laurent, Armendariz, R., Aronson, S.H., Asai, J., Atomssa, E. T., Averbeck, R., Awes, T.C., Azmoun, B., Babintsev, V., Baksay, G., Baksay, L., Baldisseri, A., Barish, K.N., Barnes, P.D., Bassalleck, B., Bathe, S., Batsouli, S., Baublis, V., Bazilevsky, A., Belikov, S., Bennett, R., Berdnikov, Y., Bickley, A.A., Boissevain, J.G., Borel, H., Boyle, K., Brooks, M.L., Buesching, H., Bumazhnov, V., Bunce, G., Butsyk, S., Campbell, S., Chang, B.S., Charvet, J.-L., Chernichenko, S., Chiba, J., Chi, C.Y., Chiu, M., Choi, I.J., Chujo, T., Chung, P., Churyn, A., Cianciolo, V., Cleven, C.R., Cole, B.A., Comets, M.P., Constantin, P., Csanad, M., Csörgö, T., Dahms, T., Das, K., David, G., Deaton, M.B., Dehmelt, K., Delagrange, H., Denisov, A., d'Enterria, D., Deshpande, A., Desmond, E.J., Dietzsch, O., Dion, A., Donadelli, M., Drapier, O., Drees, A., Dubey, A.K., Durum, A., Dzhordzhadze, V., Efremenko, Y.V., Egdemir, J., Ellinghaus, F., Emam, W.S., Enokizono, A., En'Yo, H., Esumi, S., Eyser, K.O., Fields, D.E., Finger, M., Finger Jr, M., Fleuret, F., Fokin, S.L., Fraenkel, Z., Frantz, J.E., Franz, A., Frawley, A.D., Fujiwara, K., Fukao, Y., Fusayasu, T., Gadrat, S., Garishvili, I., Glenn, A., Gong, H., Gonin, M.
Format: Artikel
Sprache:eng
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High Energy Physics - Experiment
Physics
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Zusammenfassung:The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double helicity asymmetries A_LL are presented based on a factor of five improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton, and exclude maximal values for the gluon polarization.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.76.051106