Münster 2002 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 19: Electromagnetic and Hadronic Probes II
HK 19.4: Vortrag
Dienstag, 12. März 2002, 18:00–18:15, D
Azimuthal asymmetries in pion and kaon production in SIDIS off longitudinally polarized proton and deuterium targets at HERMES — •Peter Schweitzer1, Klaus Goeke2, and Anatoli Efremov3 — 1Dipartimento di Fisica Nucleare e Teorica, Universitá degli Studi di Pavia, Pavia, Italy — 2Institut für Theoretische Physik II, Ruhr-Universität Bochum, Germany — 3Joint Institute for Nuclear Research, Dubna, 141980 Russia
Recently azimuthal asymmetries in pion production from SIDIS off a polarized proton target have been measured by HERMES and SMC. New HERMES data from a longitudinally polarized deuetrium target will be released soon (possibly in February). The asymmetries can be explained by the Collins effect and contain information on the transversity distribution function and the T-odd Collins’ fragmentation function. Recently a very successful approach has been developed which is based on 2 ingredients and explains well existing data and allows unambigous predictions for new experiments with no free parameters. Ingredient (1) is experimental information on the Collins fragmentation function from DELPHI. Ingredient (2) are results from non-perturbative calculations of the transversity distribution function in the chiral quark soliton model and in the instanton model of the QCD-vacuum.