Campus Units

Physics and Astronomy

Document Type

Article

Publication Version

Published Version

Publication Date

9-2007

Journal or Book Title

Physical Review D

Volume

76

Issue

5

First Page

051106

DOI

10.1103/PhysRevD.76.051106

Abstract

The PHENIX experiment presents results from the Relativistic Heavy Ion Collider 2005 run with polarized proton collisions at root s=200 GeV, for inclusive pi(0) production at midrapidity. 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 5 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. Using one representative model of gluon polarization it is demonstrated that the gluon spin contribution to the proton spin is significantly constrained.

Comments

This article is published as Adare, A., S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander et al. "Inclusive cross section and double helicity asymmetry for π 0 production in p+ p collisions at s= 200 GeV: Implications for the polarized gluon distribution in the proton." Physical Review D 76, no. 5 (2007): 051106.DOI:10.1103/PhysRevD.76.051106. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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