Lattice calculation of the lowest-order hadronic contribution to the muon anomalous magnetic momen

TL;DR

This paper presents lattice QCD calculations of the hadronic vacuum polarization contribution to the muon g-2, comparing quenched and 2+1 flavor results to improve understanding of the hadronic effects.

Contribution

It provides new lattice QCD calculations of the hadronic contribution to muon g-2 using improved fermion actions, including 2+1 flavor results, enhancing previous quenched studies.

Findings

Quenched results show a ~30% smaller hadronic contribution than from e+e- data.

2+1 flavor results indicate the contribution increases as quark mass decreases.

New lattice calculations support the need for precise hadronic contribution estimates.

Abstract

I present quenched domain wall fermion and 2+1 flavor improved Kogut-Susskind fermion calculations of the hadronic vacuum polarization which are used to calculate the ${\cal O}(\alpha^2)$ hadronic contribution to the anomalous magnetic moment of the muon. Together with previous quenched calcuations, the new results confirm that in the quenched theory the hadronic contribution is signifcantly smaller ($\sim 30%$) than the value obtained from the total cross section of $e^+e^-$ annhilation to hadrons. The 2+1 flavor results show an increasing contribution to $g-2$ as the quark mass is reduced.