Cross sections and double-helicity asymmetries of midrapidity inclusive charged hadrons in p+p collisions at sqrt(s)=62.4 GeV

TL;DR

This paper reports measurements of unpolarized cross sections and double-helicity asymmetries for charged hadrons in proton-proton collisions at 62.4 GeV, confirming perturbative QCD predictions and providing insights into gluon polarization.

Contribution

First measurements of charged hadron cross sections and asymmetries at this energy, testing pQCD and constraining gluon polarization models.

Findings

Data agree with next-to-leading order pQCD calculations.

Resummed pQCD calculations with next-to-leading-log accuracy also agree.

Double-helicity asymmetries disfavor large gluon polarization models.

Abstract

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 GeV are presented. The PHENIX measurements for 1.0 < p_T < 4.5 GeV/c are consistent with perturbative QCD calculations at next-to-leading order in the strong coupling constant, alpha_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 ~< x_gluon ~< 0.2, is consistent with recent global parameterizations disfavoring large gluon polarization.