Speaker
Description
We compare the isospin-one hadronic vacuum polarization (HVP) obtained from isospin-symmetric lattice QCD with that obtained from a dispersive representation employing inclusive hadronic $\tau$ decay data corrected for isospin breaking. We consider the subtracted HVP evaluated at momenta ranging from $0.5$ GeV$^2$ to $12$~GeV$^2$, together with the light-quark-connected HVP contribution to the muon anomalous magnetic moment and the short-, intermediate- and long-distance RBC/UKQCD window components thereof. Contributions from hadronic invariant masses above the $\tau$ mass are evaluated using perturbative QCD. We also consider dispersive determinations using $\tau$ data only for contributions from two-pion, or two-pion and four-pion, modes, and evaluating the remaining contributions using exclusive-mode $e^+e^-\to\mbox{hadrons}$ cross sections up to about 2 GeV. We find generally good agreement between lattice and $\tau$-based results, but we find some discrepancies between $\tau$-based and $e^+e^-$-based four-pion spectral distributions.