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Single-spin Azimuthal Asymmetries in Electroproduction of Neutral Pions in Semi-inclusive Deep-inelastic Scattering

HERMES Collaboration·A. Airapetian
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Abstract

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analysing power in the sin(phi) moment of the cross section is 0.019 +/- 0.007(stat.) +/- 0.003(syst.). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The pi^0 asymmetry is of the same size as the pi^+ asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark.

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HERMES Collaboration, A. Airapetian. 2001-06-07. Single-spin Azimuthal Asymmetries in Electroproduction of Neutral Pions in Semi-inclusive Deep-inelastic Scattering. https://doi.org/10.1103/physrevd.64.097101

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