Charged-pion cross sections and double-helicity asymmetries in polarized p plus p collisions at root s=200 GeV

We present midrapidity charged- pioninvariant cross sections, the ratio of the pi(-) to pi(+) cross sections and the charge-separated double-spin asymmetries in polarized p + p collisions at root s = p + 200 GeV. While the cross section measurements are consistent within the errors of next-to-leading-order (NLO) perturbative quantum chromodynamicspredictions (pQCD), the same calculations overestimate the ratio of the charged- pioncross sections. This discrepancy arises from the cancellation of the substantial systematic errorsassociated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor-dependent pion fragmentation functions. The charge-separated pionasymmetries presented here sample an x range of similar to 0.03-0.16 and provide unique information on the sign of the gluon-helicity distribution.