Leading order determination of the gluon polarisation from DIS events with high-p_T hadron pairs

TL;DR

This paper measures the gluon polarization in the nucleon using DIS events with high-p_T hadron pairs, employing a neural network approach to analyze data from the COMPASS experiment, and finds no significant x_g dependence.

Contribution

It introduces a neural network method to determine gluon polarization from DIS data with high-p_T hadron pairs at leading order in QCD.

Findings

Measured gluon polarization Delta g/g = 0.125 +/- 0.060 (stat.) +/- 0.063 (syst.)

Analyzed three x_g intervals covering 0.04 to 0.27

Found no significant dependence of Delta g/g on x_g

Abstract

We present a determination of the gluon polarisation Delta g/g in the nucleon, based on the longitudinal double-spin asymmetry of DIS events with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam scattering off a polarised ^6LiD target. The gluon polarisation is evaluated by a Neural Network approach for three intervals of the gluon momentum fraction x_g covering the range 0.04 < x_g < 0.27. The values obtained at leading order in QCD do not show any significant dependence on x_g. Their average is Delta g/g = 0.125 +/- 0.060 (stat.) +/- 0.063 (syst.) at x_g=0.09 and a scale of mu^2 = 3 (GeV/c)^2.