Goodbye to large ΔG? Direct estimate of gluon polarization in the nucleon

We make a first crude direct estimate of the net gluon polarization in the proton, ΔG, combining data on the asymmetries in high-pT hadron production from the HERMES, SMC and COMPASS collaborations. Although these data sample a restricted range of x, they provide no hint that ΔG is large. Fixing the normalizations of different theoretical parametrizations using the hadron asymmetry data, we find typical central values of ΔG∼0.5, with uncertainties of similar magnitude. Values of ΔG≥2 are disfavoured by Δχ2∼9 to 20, depending on the parametrization used.