Factorization of Deep Inelastic Final State Interactions in Quarkonium Models

Quarkonium production in deep-inelastic scattering

Since its discovery in 1974, the J/ψ meson has provided a useful laboratory for quantitative tests of quantum chromodynamics (QCD) and, in particular, of the interplay of perturbative and nonperturbative phenomena. The factorization formalism of nonrelativistic QCD (NRQCD) [1] provides a rigorous theoretical framework for the description of heavy-quarkonium production and decay. This formalism ...

The Unexpected Role of Final State Interactions in Deep Inelastic Scattering

Rescattering of the struck quark in Deep Inelastic Scattering implies that measured parton distributions are not directly related to the Fock state probabilities of the target wave function. The production amplitudes acquire dynamical phases, which gives rise to shadowing and diffraction in DIS. I review the kinematics and dynamics of DIS as seen in various frames and gauges. Invited talk at th...

Final State Hadrons in Deep Inelastic Processes and Colliding Beams*

The final state hadrons in polarised deep inelastic scattering

General arguments suggest that the non-perturbative background field in QCD may have a non-trivial spin structure. We discuss how this effect may be manifest in semi-inclusive measurements of fast pions in polarised deep inelastic scattering.

Final-State Interactions and Single-Spin Asymmetries in Semi-Inclusive Deep Inelastic Scattering∗

Recent measurements from the HERMES and SMC collaborations show a remarkably large azimuthal single-spin asymmetries AUL and AUT of the proton in semi-inclusive pion leptoproduction γ∗(q)p → πX. We show that final-state interactions from gluon exchange between the outgoing quark and the target spectator system lead to single-spin asymmetries in deep inelastic lepton-proton scattering at leading...