Δ G from high pT events at SMC and high pT analysis at COMPASS

Abstract

Measurements of the longitudinal spin cross section asymmetry for deep inelastic muonnucleon interactions with two high transverse momentum hadrons (pT>0.7 GeV) in the final state are presented for SMC data for polarized proton and deuteron and for data on polarized deuteron from COMPASS taken in 2002 and 2003. The muon asymmetries determined with a cut on Q2>1 GeV2 in SMC are: Ap=0.03±0.057±0.01 and Ad=0.070±0.076±0.010, respectively. From these values a gluon polarization ΔG/G=−0.20±0.28±0.10 was obtained at an average fraction of nucleon momentum carried by gluons η=0.07. The measured asymmetry (with cut on Q2>1 GeV2) in COMPASS is (Ad/D)=−0.015±0.08±0.013 where D is depolarization factor and the gluon polarization ΔG/G=0.06±0.31±0.06 was obtained at η=0.13±0.08.