GPDs in asymmetric frames

TL;DR

This paper develops a framework for calculating Generalized Parton Distributions (GPDs) in asymmetric frames using lattice QCD, addressing computational challenges and enabling better analysis of GPDs beyond symmetric frames.

Contribution

It introduces a parameterization of matrix elements in terms of Lorentz-invariant amplitudes for GPDs in asymmetric frames, facilitating lattice QCD calculations and analysis.

Findings

Parameterization of matrix elements in Lorentz-invariant form.

Relations established between symmetric and asymmetric frames.

Method to isolate higher-twist contaminations.

Abstract

It is often taken for granted that Generalized Parton Distributions (GPDs) are defined in the "symmetric" frame, where the transferred momentum is symmetrically distributed between the incoming/outgoing hadrons. However, such frames pose computational challenges for the lattice QCD practitioners. In these proceedings, we lay the foundation for lattice QCD calculations of GPDs in "asymmetric" frames, where the transferred momentum is not symmetrically distributed between the incoming/outgoing hadrons. The novelty of our work relies on the parameterization of the matrix elements in terms of Lorentz-invariant amplitudes, which not only helps in establishing relations between the said frames but also helps in isolating higher-twist contaminations. As an example, we focus on the unpolarized GPDs for spin-1/2 particles.