Pion electric polarizabilities from lattice QCD

TL;DR

This paper presents a first-principles lattice QCD calculation of the pion electric polarizability at the physical pion mass, deriving a master formula and computing the hadronic tensor using domain wall fermions.

Contribution

It introduces a novel master formula relating pion polarizability to the hadronic Compton tensor and performs the first direct lattice calculation at physical pion mass.

Findings

First lattice QCD calculation of $oldsymbol{ ext{α}_ ext{π}}$ at physical pion mass.

Derivation of a master formula relating polarizability to the hadronic tensor.

Use of domain wall fermions for direct computation.

Abstract

We report a first principle lattice calculation of the pion electric polarizability $\alpha_\pi$ at the physical pion mass. First, we derive the master formula, which relates the pion polarizabilities with the position space hadronic Compton tensor, $\langle \pi | J_\mu(x) J_\nu(0) | \pi \rangle$. The finite volume error of the master formula is exponentially suppressed by the spatial extent of the lattice. Then, the hadronic tensor is calculated using domain wall fermions (DWF) directly at physical pion mass. The gauge ensembles are generated by the RBC-UKQCD collaborations.