Cross section and double helicity asymmetry for eta mesons and their comparison to pi(0) production in p plus p collisions at root s=200 GeV
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, Delta g. This study focuses on the extraction of the double-helicity asymmetry in eta production ((p) over right arrow + (p) over right arrow -> eta + X), the eta cross section, and the eta/pi(0) 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.
This article is published as Adare, A., S. Afanasiev, C. Aidala, N. N. Ajitanand, Yasuyuki Akiba, H. Al-Bataineh, J. Alexander et al. "Cross section and double helicity asymmetry for η mesons and their comparison to π 0 production in p+ p collisions at s= 200 GeV." Physical Review D 83, no. 3 (2011): 032001. DOI:10.1103/PhysRevD.83.032001. Posted with permission.