Eur. Phys. J. C 19, 503-515
Transverse spin asymmetries in Drell-Yan processes:E. Di Salvo
Dipartimento di Fisica and I.N.F.N., Sez. Genova, Via Dodecaneso, 33, 16146 Genova, Italy
(Received: 1 February 2001 / Published online: 23 March 2001 -© Springer-Verlag 2001)
We consider two different spin asymmetries in Drell-Yan processes generated by the collisions of an unpolarized proton beam on transversely polarized protons: the muon helicity asymmetry and the left-right asymmetry. We calculate the asymmetries in the framework of the QCD improved parton model, taking into account the parton transverse momentum and considering first-order QCD corrections. The muon helicity asymmetry is sensitive to the quark transversity distribution and is nonvanishing even at zero order. On the contrary the left-right asymmetry vanishes at zero order but not at first order in the QCD coupling constant, as a result of the gluon contribution.
© Società Italiana di Fisica, Springer-Verlag 2001