Flavor Twisted Boundary Conditions, Pion Momentum, and the Pion Electromagnetic Form Factor

TL;DR

This paper explores how partially twisted boundary conditions in lattice QCD enable precise calculation of the pion electromagnetic form factor at continuous momentum transfer, with controlled finite volume effects.

Contribution

It demonstrates the use of twisted boundary conditions to compute the pion form factor at arbitrary momenta and analyzes volume effects on the dispersion relation.

Findings

Pion dispersion relation is volume-dependent under twisted boundary conditions.

Pion electromagnetic form factor can be computed at continuous momentum transfer.

Finite volume effects are theoretically manageable for charge radius extraction.

Abstract

We investigate the utility of partially twisted boundary conditions in lattice calculations of meson observables. For dynamical simulations, we show that the pion dispersion relation is modified by volume effects. In the isospin limit, we demonstrate that the pion electromagnetic form factor can be computed on the lattice at continuous values of the momentum transfer. Furthermore, the finite volume effects are under theoretical control for extraction of the pion charge radius.