Probing the nucleon's transversity and the photon's distribution amplitude in lepton pair photoproduction

TL;DR

This paper proposes a novel method to access the proton's transversity distribution via lepton pair photoproduction, utilizing interference effects with the photon’s chiral-odd distribution amplitude, revealing new spin observable phenomenology.

Contribution

It introduces a new approach to probe the proton's transversity distribution using interference in lepton pair photoproduction involving the photon’s chiral-odd distribution amplitude.

Findings

Potential to measure transversity through interference effects

Identification of unique spin observables in photoproduction

Connection between photon distribution amplitude and QCD vacuum properties

Abstract

We describe a new way to access the chiral odd transversity parton distribution in the proton through the photoproduction of lepton pairs. The basic ingredient is the interference of the usual Bethe Heitler or Drell-Yan amplitudes with the amplitude of a process, where the photon couples to quarks through its chiral-odd distribution amplitude, which is normalized to the magnetic susceptibility of the QCD vacuum. A promising phenomenology of single and double spin observables emerges from the unusual features of this amplitude.