Results on longitudinal spin physics at COMPASS

Malte Wilfert, C. Marquet, B. Pire, F. Sabatie
2016 EPJ Web of Conferences  
The COMPASS experiment at the CERN SPS has taken data on deep inelastic scattering of polarised muons on a polarised NH 3 target in 2007 and 2011 and on a polarised LiD target in 2002-2004 and 2006. The new results on the longitudinal double spin asymmetry A p 1 and the spin-dependent structure function g p 1 obtained from the 2011 data set are presented. These results are used in a NLO QCD fit to the world data to obtain the polarised parton distributions. Also an update of the results on the
more » ... jorken sum rule, connecting the integral of the non-singlet spin-dependent structure function with the ratio of the weak coupling constants, will be given. Direct access to the gluon polarisation is possible via the photon gluon fusion process in semi-inclusive deep inelastic scattering. This process is studied using the p T dependence of charged hadron asymmetries. The latest results indicate a positive gluon polarisation in the kinematic region of COMPASS 1 1 2 20 02 23 3 7KLV LV DQ 2SHQ $FFHVV DUWLFOH GLVWULEXWHG XQGHU WKH WHUPV RI WKH &UHDWLYH &RPPRQV $WWULEXWLRQ /LFHQVH ZKLFK SHUPLWV XQUHVWULFWHG XVH GLVWULEXWLRQ DQG UHSURGXFWLRQ LQ DQ\ PHGLXP SURYLGHG WKH RULJLQDO ZRUN LV SURSHUO\ FLWHG 4 ,
doi:10.1051/epjconf/201611201023 fatcat:2dt227it6nfnxl4bq2ek5u35o4