Slope and curvature of the hadron vacuum polarization at vanishing virtuality from lattice QCD

TL;DR

This paper uses lattice QCD with physical quark masses and multiple lattice spacings to accurately compute the slope and curvature of the hadron vacuum polarization at zero virtuality, including all contributions.

Contribution

It provides the first comprehensive lattice QCD calculation of the slope and curvature of the hadron vacuum polarization at zero momentum transfer, including connected and disconnected contributions.

Findings

Accurate determination of the slope and curvature at zero virtuality.

Inclusion of all quark flavor contributions, including charm.

Use of multiple lattice spacings for continuum extrapolation.

Abstract

We compute the slope and curvature, at vanishing four-momentum transfer squared, of the leading order hadron vacuum polarization function, using lattice QCD. Calculations are performed with 2+1+1 flavors of staggered fermions directly at the physical values of the quark masses and in volumes of linear extent larger than 6fm. The continuum limit is carried out using six different lattice spacings. All connected and disconnected contributions are calculated, up to and including those of the charm.