COMPASS experiment at CERN: hadron spectroscopy and open charm results

Abstract

COmmon Muon and Proton Apparatus for Structure and Spectroscopy (COMPASS) is a fixed target experiment at CERN dedicated to studies of the spin structure of the nucleon and of the spectroscopy of hadrons. During the years 2002-2004 and 2006-2007, the COMPASS collaboration has collected a large amount of data by scattering polarized 160 GeV/c muons on polarized 6 LiD and NH 3 targets. These data were used to evaluate the gluon contribution to the nucleon spin. The gluon polarization Δg g was directly measured from the cross-section helicity asymmetry of D 0 mesons production in the photon-gluon fusion reaction.During 2008 and 2009, the world leading data sets were collected with hadron beams which are currently being analyzed using Partial Wave Analysis (PWA) technique. COMPASS is performing a search for J PC -exotic mesons, glueballs and hybrids, through light hadron spectroscopy in high energy 190 GeV/c hadron-proton reactions using both centrally produced and diffractive events. Preliminary results from these searches are discussed.