Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions √s = 200 GeV

We report a measurement of the longitudinal double-spin asymmetry ALL and the differential cross section for inclusive π0 production at midrapidity in polarized proton collisions at √s = 200 GeV. The cross section was measured over a transverse momentum range of 1 < pT < 17 GeV/c and found to be in good agreement with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry was measured in the range of 3.7 < pT < 11 GeV/c and excludes a maximal positive gluon polarization in the proton. The mean transverse momentum fraction of π0's in their parent jets was found to be around 0.7 for electromagnetically triggered events.