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Azimuthal asymmetry in electro-production of neutral pions in SIDIS

A. V. Efremov·K. Goeke·P. Schweitzer
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Abstract

Recently HERMES has observed an azimuthal asymmetry in electro-production of neutral pions in semi-inclusive deep-inelastic scattering of unpolarized positrons off longitudinally polarized protons. This asymmetry (like those observed in the production of charged pions) is well reproduced theoretically by using the non-perturbative calculation of the proton transversity distribution in the effective chiral quark-soliton model combined with experimental DELPHI-data on the new T-odd Collins fragmentation function. There are no free, adjustable parameters in the analysis. Using the $z$-dependence of the HERMES azimuthal asymmetry and the calculated transversity distributions the z-dependence of the Collins fragmentation function is obtained. The value obtained from HERMES data is consistent with the DELPHI result, even though these results refer to different scales.

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A. V. Efremov, K. Goeke, P. Schweitzer. 2001-09-27. Azimuthal asymmetry in electro-production of neutral pions in SIDIS. https://doi.org/10.1016/s0370-2693(01)01258-8

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