New measurements of ΔG/G at COMPASS

One of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, ΔG/G. It is determined from spin asymmetries in the scattering of polarised muons at 160 GeV/c on a polarised LiD target. The gluon polarisation is accessed by the selection of photon-gluon fusion events. Such events are tagged either with a charmed meson or a hadron pair with high transverse momenta in the final state. The selection of charmed mesons is based on the reconstruction of decayed D⋆ and D0 mesons in the COMPASS spectrometer. For the high-pT hadron pairs two independent analyses are performed in the kinematic regimes of DIS (Q2>12(GeV/c)) and quasi-real photoproduction (Q2<12(GeV/c). The results presented in this paper were obtained from the data coming from 2002–2004 for the open charm and the high pT with Q2<12(GeV/c) channels resp. from 2002–2003 for the high pT with Q2>12(GeV/c) channel.