Speaker
Anna Martin
(Universita e INFN (IT))
Description
COMPASS, a fixed target experiment at the CERN SPS, is measuring the partonic structure of the nucleon since 2002. An important part of this program are the measurements of transverse spin effects in semi-inclusive deep inelastic scattering of high energy muons off transversely polarized deuteron and proton solid state targets. This talk is dedicated to the measurements of the Collins and Sivers asymmetries, which give access to the transversity and the Sivers parton distribution functions. The proton and deuteron COMPASS results are reviewed. Particular focus is put on the very recent results from the data collected in 2010 using the transversely polarized proton target, which show asymmetries clearly different from zero and confirm the results from the 2007 data but with considerably improved accuracy. The comparison of these COMPASS data with the results from experiments using lower energy incoming leptons gives important constrains for the Q2 evolution of the transverse momentum dependent distribution and fragmentation functions.
Author
Anna Martin
(Universita e INFN (IT))
