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- Title
Final-State Interactions and Single-Spin Asymmetries in Semi-Inclusive Deep Inelastic Scattering.
- Authors
Brodsky, Stanley J.; Hwang, Dae Sung; Schmidt, Ivan
- Abstract
Recent measurements from the HERMES and SMC collaborations show a remarkably large azimuthal single-spin asymmetries A[SUBUL] and A[SUBUT] 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 leads to single-spin asymmetries in deep inelastic lepton-proton scattering at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality q[SUP2] at fixed x[SUBbj]. The existence of such single-spin asymmetries requires a phase difference between two amplitudes coupling the proton target with J[SUPz,SUBp] = ±½ to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. We show that the exchange of gauge particles between the outgoing quark and the proton spectators produces a Coulomb-like complex phase which depends on the angular momentum L[SUPz] of the proton's constituents and thus is distinct for different proton spin amplitudes. The single-spin asymmetry which arises from such final-state interactions does not factorize into a product of structure function and fragmentation function, and it is not related to the transversity distribution δq(x, Q) which correlates transversely polarized quarks with the spin of the transversely polarized target nucleon.
- Subjects
INELASTIC scattering; PROTON scattering; QUANTUM chromodynamics
- Publication
International Journal of Modern Physics A: Particles & Fields; Gravitation; Cosmology; Nuclear Physics, 2003, Vol 18, Issue 8, p1327
- ISSN
0217-751X
- Publication type
Article
- DOI
10.1142/S0217751X03014678