Leading-order determination of the gluon polarization from high-pT hadron electroproduction

Longitudinal double-spin asymmetries of charged hadrons with high transverse momentum pT have been measured in electroproduction using the Hermes detector at Hera. Processes involving gluons in the nucleon have been enhanced relative to others by selecting hadrons with pT typically above 1 GeV. In this kinematic domain the gluon polarization has been extracted in leading order making use of the model embedded in the Monte Carlo Generator Pythia 6.2. The gluon polarization obtained from single inclusive hadrons in the pT range 1 GeV<pT<2.5 GeV using a deuterium target is (Δg)/(g)(x,μ2)=0.049±0.034(stat)±0.010(sys-exp)-0.099+0.126(sys-models) at a scale left angle μ2 right angle =1.35 GeV2 and left angle x right angle =0.22. For different final states and kinematic domains, consistent values of (Δg)/(g) have been found within statistical uncertainties using hydrogen and deuterium targets. (orig.)