Dresden 2000 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 2: Theorie I

HK 2.4: Vortrag

Montag, 20. März 2000, 15:00–15:15, B 81

Quark– and antiquark transversity distributions: Model estimates and predictions for experiments — •P. Schweitzer², A.V. Efremov¹, K. Goeke², M.V. Polyakov^2,3, P.V. Pobylitsa^2,3, D. Urbano^2,4, and C. Weiss² — ¹JINR Dubna, Russia — ²Institut f. Theoretische Physik II, Ruhr–Universität Bochum — ³Petersburg Nuclear Physics Institute, Russia — ⁴Engineering Faculty, University at Porto, Portugal

In addition to the usual longitudinally polarized twist–2 quark– and antiquark distributions the nucleon is characterized also by the so-called transversity distributions, which are chirally–odd and cannot be measured in inclusive DIS. We report about a model calculation of the flavor–nonsinglet and singlet transversity distributions at a low normalization point in the large–N_c limit (chiral quark–soliton model of the nucleon). The results are used to make predictions for two types of semi-inclusive experiments which would allow to measure transversity: i) Double spin asymmetries in Drell–Yan lepton pair production in transversely polarized NN collisions (e.g. at RHIC). ii) Single–spin azimuthal asymmetries in hadron production in semi-inclusive eN scattering, where we use the values for the T–odd fragmentation functions extracted from the DELPHI data. We compare our theoretical predictions for the single–spin asymmetries with the recent HERMES and SMC measurements.