Cross section and double helicity asymmetry for η mesons and their comparison to π0 production in p+p collisions at √s=200GeV

Abstract

Measurements of double-helicity asymmetries in inclusive hadron production in polarized p+p collisions are sensitive to helicity-dependent parton distribution functions, in particular, to the gluon helicity distribution, Δg. This study focuses on the extraction of the double-helicity asymmetry in η production (p→+p→→η+X), the η cross section, and the η/π0 cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to access the helicity-dependent parton distribution functions. © 2011 American Physical Society.