Pretzelosity distribution function h_1T^perp and the single spin asymmetry A_UT^sin(3phi-phi_S)

TL;DR

This paper explores the pretzelosity distribution function h_1T^perp, its theoretical properties, model predictions, and its role in single spin asymmetries in semi-inclusive deep inelastic scattering, with implications for future experiments.

Contribution

It provides a detailed review of pretzelosity, its relation to relativistic effects, and makes predictions for experimental measurements of related asymmetries.

Findings

Pretzelosity relates to the difference between helicity and transversity distributions.

It can be accessed via the Collins effect in semi-inclusive DIS.

Predictions are made for asymmetries in future experiments.

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.