title: Sivers effect in two-hadron electroproduction.
abstract: The Sivers effect in single hadron semi-inclusive deep inelastic scattering on a transversely polarized nucleon describes the modulation of the cross section with the sine of the azimuthal angle between the produced hadron's transverse momentum and the nucleon spin (P(h) and φ(S), respectively). This effect is attributed to the so-called Sivers parton distribution function of the nucleon. We employ a simple phenomenological parton model to derive the relevant cross section for two-hadron production in semi-inclusive deep inelastic scattering including the Sivers effect. We show that the Sivers effect can be observed in such a process as sine modulations involving the azimuthal angles φ(T) and φ(R) of both the total and the relative transverse momenta of the hadron pair. The existence of the modulation with respect to φ(R) is new. Finally, we employ a modified version of the lepto Monte Carlo event generator that includes the Sivers effect to estimate the size of single spin asymmetries corresponding to these modulations. We show that sin(φ(R)-φ(S)) modulations can be significant, especially if we impose asymmetric cuts on the momenta of the hadrons in the pairs.
authors.affiliation: Yerevan Physics Institute, 2 Alikhanyan Brothers St., 375036 Yerevan, Armenia and INFN, Sezione di Torino, 10125 Torino, Italy.
authors.forename: Aram
authors.initials: A
authors.lastname: Kotzinian
authors.affiliation: ARC Centre of Excellence for Particle Physics at the Tera-scale, and CSSM, School of Chemistry and Physics, The University of Adelaide, Adelaide SA 5005, Australia.
authors.forename: Hrayr H
authors.initials: HH
authors.lastname: Matevosyan
authors.affiliation: ARC Centre of Excellence for Particle Physics at the Tera-scale, and CSSM, School of Chemistry and Physics, The University of Adelaide, Adelaide SA 5005, Australia.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Thomas