Eur. Phys. J. C 19, 503-515
DOI: 10.1007/s100520100619
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)
Abstract
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