Lattice QCD Methods for Hadronic Polarizabilities

TL;DR

This paper reviews lattice QCD techniques for calculating hadronic electromagnetic polarizabilities, emphasizing methods involving uniform electromagnetic fields and discussing the potential for direct lattice determination and comparison with chiral dynamics predictions.

Contribution

It introduces a novel method for handling charged particle correlation functions in magnetic fields within lattice QCD simulations.

Findings

Chiral dynamics predicts pion mass dependence of polarizabilities.

Lattice QCD methods can test these predictions.

A new approach improves calculations for charged particles in magnetic fields.

Abstract

Chiral dynamics makes definitive predictions for the electromagnetic polarizabilities of hadrons near the chiral limit; but, agreement with experiment is tenuous in some cases. We provide an overview of lattice QCD methods to compute the electric and magnetic polarizabilities of hadrons. Central to these methods is the lattice simulation of quarks in uniform, classical electromagnetic fields. A long-term goal is the determination of polarizabilities directly from lattice computations, however, in the near term, one may need to rely on partially quenched chiral perturbation theory. Nonetheless the same striking predictions for the pion mass dependence of electric and magnetic polarizabilities can be made from chiral dynamics, and tested with lattice QCD. A particular focus is a novel new method to handle charged particle correlation functions in magnetic fields.