Measurement of the Collins and Sivers asymmetries on transversely polarised protons
Alekseev, M.~G. and Alexakhin, V.~Y. and Alexandrov, Y. and Alexeev, G.~D. and Amoroso, A. and Austregesilo, A. and Badelek, B. and Balestra, F. and B
Keywords
COMPASS, Spin Quarks, structure functions, transversity
Abstract
The Collins and Sivers asymmetries for charged hadrons produced in deeply inelastic scattering on transversely polarised protons have been extracted from the data collected in 2007 with the CERN SPS muon beam tuned at 160 GeV/c. At large values of the Bjorken x variable non-zero Collins asymmetries are observed both for positive and negative hadrons while the Sivers asymmetry for positive hadrons is slightly positive over almost all the measured x range. These results nicely support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions.
