Transversity Distribution Does Not Contribute to Hard Exclusive Electroproduction of Mesons

TL;DR

This paper proves that the transversity distribution does not contribute to the hard exclusive electroproduction of mesons at leading twist, correcting previous calculations and reinforcing helicity conservation principles.

Contribution

It demonstrates that the leading-twist hard-scattering coefficient for transversely polarized meson production vanishes, clarifying the role of transversity in such processes and correcting prior NLO results.

Findings

Leading-twist coefficient for transversely polarized meson production vanishes to all orders.

Previous NLO calculation was incorrect due to missing collinear subtractions.

Validates helicity selection rules based on chirality and helicity conservation.

Abstract

We show that in hard exclusive electroproduction, ep-->eVp, the leading-twist hard-scattering coefficient for the production of a transversely polarized vector meson V vanishes to all orders of perturbation theory. This implies that this process cannot be used to measure the skewed transversity distribution of quarks in a hadron. In contrast, a recent calculation obtained a non-zero value at NLO. We show that this calculation is incorrect because it failed to include the necessary collinear subtractions. Our method of proof also applies to other processes whose hard-scattering coefficients are constrained by chirality and helicity conservation, and thus validates helicity selection rules based on these symmetries.