New ideas for g-2 on the lattice

TL;DR

This paper introduces a method to improve lattice QCD calculations of the hadronic vacuum polarization by using twisted boundary conditions and explores theoretical relations between different contributions at NLO in chiral perturbation theory.

Contribution

It presents a novel approach to enhance q^2-resolution in lattice QCD and derives an exact relation between connected and disconnected contributions at NLO.

Findings

Improved q^2-resolution using twisted boundary conditions.

Derived exact relation between contributions at NLO.

Discussed extensions to N_f > 2 theories.

Abstract

Using iso-spin symmetry the quark-connected and disconnected contributions to the hadronic vacuum polarisation in a theory with N_f=2 flavours can be described as independent correlation functions, respectively. We show how this allows to use twisted boundary conditions for the connected contribution in order to improve the q^2-resolution in lattice QCD. Furthermore we derive an exact relation between the connected and the disconnected contributions at NLO in chiral perturbation theory. We discuss extensions to theories with more than 2 dynamical flavours.