Determination of Delta G/G from Open Charm events at COMPASS

Abstract

One of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, Delta G/G. It is determined from spin asymmetries in the scattering of 160 GeV/c polarised muons on a polarised LiD target. The gluon polarisation is accessed by the selection of photon-gluon fusion (PGF) events. A very clean selection of PGF events can be obtained with charmed mesons in the final state. Their detection is based on the reconstruction of D* and D0 mesons in the COMPASS spectrometer. The analysis method for the first measurement of Delta G/G from the open charm channel is described and the result from COMPASS for the 2002-2004 data taking period is presented.Comment: Talk given at the XV International Workshop on Deep-Inelastic Scattering and Related Subjects, April 16-20, 2007, Munich, Germany http://www.mppmu.mpg.de/dis200