Unpolarized cross sections and double-helicity asymmetries of single-inclusive positive and negative charged hadrons at midrapidity from $p+p$ collisions at $\sqrt{s}=62.4\mathrm{GeV}$ are presented. The PHENIX measurement of the cross sections for $1.0<p_T<4.5\mathrm{GeV}/c$ are consistent with perturbative QCD calculations at next-to-leading order in the strong-coupling constant, ${\mathrm{<ruby><rb>\alpha </rb><rt>あるふぁ</rt></ruby>}}_s$. Resummed pQCD calculations including terms with next-to-leading-log accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double-helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum-fraction range of $0.05\lesssim x_{\mathrm{gluon}}\lesssim 0.2$, is consistent with recent global parametrizations disfavoring large gluon polarization.

• Received 21 February 2012

DOI:https://doi.org/10.1103/PhysRevD.86.092006