Measurement of the Collins and Sivers asymmetries on transversely polarised protons

M.G. Alekseev (1) , J. Ball (2) , Y. Bedfer (2) , E. Burtin (2) , A. El Alaoui (2) , A. Ferrero (2) , N. d'Hose (2) , G. Jegou (2) , F Kunne (2) , Jean-Marc Legoff (2) , A. Magnon (2) , C. Marchand (2) , D Neyret (2) , S. Platchkov (2) , F. Robinet (2) , Collaboration Compass

1 INFN, Sezione di Torino - Istituto Nazionale di Fisica Nucleare, Sezione di Torino
2 DPHN - Département de Physique Nucléaire (ex SPhN)

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 strongly support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

M.G. Alekseev, J. Ball, Y. Bedfer, E. Burtin, A. El Alaoui, et al.. Measurement of the Collins and Sivers asymmetries on transversely polarised protons. Physics Letters B, 2010, 692 (4), pp.240. ⟨hal-01128994⟩