Gluon polarisation from high transverse momentum hadron pairs production (COMPASS)

Abstract

A new preliminary result of a gluon polarisation \Delta G/G obtained selecting high transverse momentum hadron pairs in DIS events with Q^2>1 (GeV/c)^2 is presented. Data has been collected by COMPASS at CERN during the 2002-2004 years. In the extraction of $\Delta G/G$ contributions coming from the leading order $\gamma q$ and QCD processes are taken into account. A new weighting method based on a neural network approach is used. Also a preliminary result of \Delta G/G for events with Q^2<1 (GeV/c)^2 is presented.Comment: Advanced Studies Institute On Symmetries And Spin (SPIN-Praha-2008) 20-26 Jul 2008, Prague, Czech Republic. The proceedings of the ASI will be published in The European Physical Journal Special Topics (EJP ST) Serie