Cross section and transverse single-spin asymmetry of η mesons in p↑+p collisions at s =200GeV at forward rapidity

Abstract

We present a measurement of the cross section and transverse single-spin asymmetry (AN) for η mesons at large pseudorapidity from s=200GeV p↑+p collisions. The measured cross section for 0.5<pT<5.0GeV/c and 3.0<|η|<3.8 is well described by a next-to-leading-order perturbative-quantum-chromodynamics calculation. The asymmetries AN have been measured as a function of Feynman-x (xF) from 0.2<|xF|<0.7, as well as transverse momentum (pT) from 1.0<pT<4.5GeV/c. The asymmetry averaged over positive xF is 〈AN〉=0.061±0.014. The results are consistent with prior transverse single-spin measurements of forward η and π0 mesons at various energies in overlapping xF ranges. Comparison of different particle species can help to determine the origin of the large observed asymmetries in p↑+p collisions. © 2014 American Physical Society.