Improved measurement of double helicity asymmetry in inclulsive midrapidity π0 production for polarized p + p collisions at √s = 200 GeV

PHENIX Collaboration

Enokizono Akitomo

Hachiya Takashi

Harada Hiroyuki

Haruna Kohta

Homma Kensuke

Kohara Ryota

Nakamura Tomoaki

Shigaki Kenta

Sugitate Toru

Tsuchimoto Yuji

Physical Review D - Particles, Fields, Gravitation and Cosmology

We present an improved measurement of the double helicity asymmetry for π0 production in polarized proton-proton scattering at √s=200GeV employing the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The improvements to our previous measurement come from two main factors: Inclusion of a new data set from the 2004 RHIC run with higher beam polarizations than the earlier run and a recalibration of the beam polarization measurements for the earlier run, which resulted in reduced uncertainties and increased beam polarizations. The results are compared to a Next to Leading Order (NLO) perturbative Quantum Chromodynamics (pQCD) calculation with a range of polarized gluon distributions.

helicity (elementary particles)

proton-proton inclusive interactions

polarisation in elementary particle interactions

quantum chromodynamics

perturbation theory

eng

American Physical Society

Copyright (c) 2006 The American Physical Society.

[ISSN] 1550-7998

[DOI] 10.1103/PhysRevD.73.091102

[NCID] AA00773624

[DOI] http://dx.doi.org/10.1103/PhysRevD.73.091102