Towards a precise lattice determination of the leading hadronic contribution to (g-2)_mu

TL;DR

This paper presents a lattice QCD calculation of the leading hadronic contribution to the muon's anomalous magnetic moment, exploring systematic effects and providing a preliminary estimate with controlled uncertainties.

Contribution

It introduces a lattice QCD approach with improved techniques and systematic error analysis to estimate the hadronic contribution to (g-2)_mu.

Findings

Preliminary value of a_mu(HLO)=618(64)×10^(-10)

Dependence of a_mu(HLO) on pion mass observed

Systematic errors analyzed and discussed

Abstract

We report on our computation of the leading hadronic contribution to the anomalous magnetic moment of the muon using two dynamical flavours of non-perturbatively O(a) improved Wilson fermions. The strange quark is introduced in the quenched approximation. Partially twisted boundary conditions are applied to improve the momentum resolution in the relevant integral. Our results, obtained at three different values of the lattice spacing, allow for a preliminary study of discretization effects. We explore a wide range of lattice volumes, namely 2 fm < L < 3 fm, with pion masses from 600 to 280 MeV and discuss different chiral extrapolations to the physical point. We observe a non-trivial dependence of a_mu(HLO) on m_pi especially for small pion masses. The final result, a_mu(HLO)=618(64)*10^(-10), is obtained by considering only the quark connected contribution to the vacuum polarization. We present a detailed analysis of systematic errors and discuss how they can be reduced in future simulations.