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Pretzelosity distribution function h^perp_1T and the single spin asymmetry A sin(3phi-phi(s))(UT).

  • Author(s): Avakian, H.
  • Efremov, A.V.
  • Schweitzer, P.
  • Yuan, Feng
  • et al.
Abstract

The leading twist transverse momentum dependent parton distribution function h_1T^perp, which is sometimes called "pretzelosity," is studied. We review the theoretical properties of this function, and present bag model predictions. We observe an interesting relation valid in a large class of relativistic models: The difference between helicity and transversity distributions, which is often said to be a 'measure of relativistic effects' in nucleon, is nothing but the pretzelosity distribution. Pretzelosity is chirally odd and can be accessed in combination with the Collins effect in semi-inclusive deep inelastic scattering, where it gives rise to an azimuthal single spin asymmetry proportional to sin(3phi-phi_S). We discuss the preliminary deuteron target data from COMPASS, on that observable and make predictions for future experiments on various targets at JLab, COMPASS and HERMES.

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