Inclusive cross section and double helicity asymmetry for π⁰ production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

2007/04/26 by PHENIX Collaboration, A. Adare · 1 citation
Physics and Astronomy · #hep-ex

paper · pdf · doi:10.1103/physrevd.76.051106

published as Phys.Rev.D76:051106,2007 · 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid Communications. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html

Abstract

The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive π⁰ 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.

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• Elliptic flow of π⁰ mesons in Cu+Au collisions at √s__NN=200 GeV and U+U at √s__NN=193 GeV

Related

• Recent PHENIX Results on pi+, pi-, and eta Production in polarized pp Collisions at RHIC at sqrt(s) = 200 GeV
• Double Helicity Asymmetry in π⁰ Production at Midrapidity in Polarized p+p Collisions at √(s)=510 GeV
• Recent results in high-energy longitudinal polarized proton-proton collisions at 200GeV at RHIC
• Gluon Double-Spin Asymmetry in the Longitudinally Polarized p+p Collisions
• Longitudinal double helicity asymmetry A_LL from direct photon, jet and charged pion production in polarized p+p collisions