Can VMD improve the estimate of the muon g-2 ?

TL;DR

This paper demonstrates that using a Vector Meson Dominance (VMD) model improves the theoretical estimate of the muon g-2 by refining the hadronic vacuum polarization calculation, aligning tau decay data with e+e- results.

Contribution

The study introduces a VMD-based approach to enhance the accuracy of hadronic vacuum polarization estimates for muon g-2 calculations.

Findings

VMD input significantly improves the hadronic vacuum polarization estimate.

Tau decay spectrum aligns with e+e- annihilation data except for the branching ratio.

The accepted value of Br(τ → ππν_τ) is the only experimental discrepancy.

Abstract

We show that a VMD based theoretical input allows for a significantly improved accuracy for the hadronic vacuum polarization of the photon which contributes to the theoretical estimate of the muon g-2. We also show that the only experimental piece of information in the $\tau$ decay which cannot be accounted for is the accepted value for ${\rm Br}(\tau \ra \pi \pi \nu_\tau)$, while the spectum lineshape is in agreement with expectations from $e^+ e^-$ annihilations.