Spin-independent and double-spin cos(phi) asymmetries in semi-inclusive pion electroproduction

We consider the cos(phi) dependence of the longitudinal double-spin asymmetry for charged pion electroproduction in semi-inclusive deep inelastic scattering, emphasizing intrinsic transverse momentum effects. This azimuthal asymmetry allows to measure the cos(phi) moments of the unpolarized and double-spin cross-section, simultaneously. The size of the asymmetry, in the approximation where all twist-3 interaction-dependent distribution and fragmentation functions are set to zero, is estimated for HERMES kinematics; both the spin-independent and the double-spin cos(phi) moments are predicted to be sizeable and negative.Comment: LaTeX, 4 pages, 4 figures. Discussion on the acceptance effects added; recent parameterizations of distribution and fragmentation functions used, figures replaced. Final version to appear in Physics Letters

Single Spin Asymmetries in Semi-Inclusive Electroproduction: Access to Transversity

We discuss the quark transversity distribution function and a possible way to access it through the measurement of single spin azimuthal asymmetry in semi-inclusive single pion electroproduction on a transversely polarized target.Comment: 5 pages, Latex using aipproc.sty (included), to appear in proceedings of "Second Workshop on Physics with an Electron Polarized Light Ion Collider", Sept. 14-16, 2000, MIT, Cambridge, US

Azimuthal Asymmetries: Access to Novel Structure Functions

One of the most interesting consequence of non-zero intrinsic transverse momentum of partons in the nucleon is the nontrivial azimuthal dependence of the cross section of hard scattering processes. Many of the observable asymmetries contain unknown functions which provide essential information on the quark and gluon structure. Several of them have been studied in the last few years; we discuss their qualitative and quantitative features in semi-inclusive DIS.Comment: 6 pages, LaTeX, 7 eps figures, Talk presented at the 15th International Spin Physics Symposium, Spin 2002, Brookhaven National Laboratory, September 9-14, 200

Kinematical contributions to the transverse asymmetry in semi-inclusive DIS

We discuss the contributions of the transverse spin component of the target to the double-spin asymmetries in semi-inclusive deep inelastic scattering of longitudinally polarized electrons off longitudinally polarized protons.Comment: LaTeX, 4 pages, 4 figures, uses espcrc1.sty, talk presented at the European Workshop on the QCD Structure of the Nucleon (QCD-N'02), Ferrara, Italy, April 3-6, 200

Double-spin cos(phi) Asymmetry in Semi-inclusive Electroproduction

We consider the double-spin cos(phi) asymmetry for pion electroproduction in semi-inclusive deep inelastic scattering of longitudinally polarized leptons off longitudinally polarized protons. We estimate the size of the asymmetry in the approximation where all twist-3 interaction-dependent distribution and fragmentation functions are set to zero. In that approximation at HERMES kinematics a sizable negative cos(phi) double-spin asymmetry for pi+ electroproduction is predicted.Comment: LaTeX, 5 pages, 2 figures. Minor changes, figure modified. Final version to appear in Phys.Lett.