Measurement of the virtual-photon asymmetry A _2 and the spin-structure function g _2 of the proton

摘要

measurement of the virtual-photon asymmetry A_2(x,Q~2) and of the spin-structure function g2(x,Q~2) of the proton are presented for the kinematic range 0.004 > x > 0.9 and 0.18 GeV~2 > Q~2 > 20 GeV~2. The data were collected by the HERMES experiment at the HERA storage ring at DESY while studying inclusive deep-inelastic scattering of 27.6 GeV longitudinally polarized leptons off a transversely polarized hydrogen gas target. The results are consistent with previous experimental data from CERN and SLAC. For the x-range covered, the measured integral of g2(x) converges to the null result of the Burkhardt–Cottingham sum rule. The x~2 moment of the twist-3 contribution to g2(x) is found to be compatible with zero.