On the cos 2φ asymmetry in unpolarized leptoproduction
نویسندگان
چکیده
We investigate the origin of the cos 2φ azimuthal asymmetry in unpolarized semiinclusive DIS. The contributions to this asymmetry arising from the intrinsic transverse motion of quarks are explicitly evaluated, and predictions for the HERMES and COMPASS kinematic regimes are presented. We show that the effect of the leading-twist Boer-Mulders function h1 (x,k 2 T ), which describes a correlation between the transverse momentum and the transverse spin of quarks, is quite significant and may also account for a part of the cos 2φ asymmetry measured by ZEUS in the perturbative domain.
منابع مشابه
Initial - State Interactions in the Unpolarized
We show that initial-state interactions contribute to the cos 2φ distribution in unpolarized Drell-Yan lepton pair production p p and p p → l+l−X, without suppression. The asymmetry is expressed as a product of chiral-odd distributions h1 (x1,p 2 ⊥) × h ⊥ 1 (x2,k 2 ⊥), where the quark-transversity function h1 (x,p 2 ⊥) is the transverse momentum dependent, light-cone momentum distribution of tr...
متن کاملInitial - State Interactions in the Unpolarized Drell - Yan Process ∗
We show that initial-state interactions contribute to the cos 2φ distribution in unpolarized Drell-Yan lepton pair production p p and p p → `+`−X, without suppression. The asymmetry is expressed as a product of chiral-odd distributions h1 (x1, p 2 ⊥) × h ⊥ 1 (x2, k 2 ⊥), where the quark-transversity function h1 (x, p 2 ⊥) is the transverse momentum dependent, light-cone momentum distribution of...
متن کامل5 Azimuthal asymmetry in unpolarized πN Drell - Yan process
Taking into account the effect of final state interaction, we calculate the non-zero (näive) T -odd transverse momentum dependent distribution h1 (x,k 2 ⊥) of the pion in a quark-spectator-antiquark model with effective pion-quark-antiquark coupling as a dipole form factor. Using the model result we estimate the cos 2φ asymmetries in the unpolarized πN Drell-Yan process which can be expressed a...
متن کامل-Odd Effects in Unpolarized Drell-Yan Scattering
We consider the leading twist T -odd contributions as the dominant source of the cos 2φ azimuthal asymmetry in unpolarized pp̄ → μμ X dilepton production in Drell-Yan Scattering. This asymmetry contains information on the distribution of quark transverse spin in an unpolarized proton. In a parton-spectator framework we estimate these asymmetries at 50 GeV center of mass energy. This azimuthal as...
متن کاملNucleon Transversity Properties through Ep Scattering *
The T-odd distribution functions contributing to transversity properties of the nucleon and their role in fueling nontrivial contributions to azimuthal asymmetries in semi-inclusive deep inelastic scattering are investigated. We use a dynamical model to evaluate these quantities in terms of HERMES kinematics. We point out how the measurements of cos 2φ asymmetry may indicate the presence of T-o...
متن کامل