Tension between $e^+e^-\to\eta\pi^-\pi^+$ and $\tau^-\to\eta\pi^-\pi^0\nu_\tau$ data and non-standard interactions

TL;DR

This paper investigates a discrepancy between $e^+e^- o ext{eta} ext{pi} ext{pi}$ cross-section measurements and tau decay spectra, showing it cannot be explained by heavy new physics non-standard interactions, and introduces a new framework for such studies.

Contribution

The paper presents the first framework to analyze non-standard model contributions in three-meson tau decays, addressing observed experimental discrepancies.

Findings

Discrepancy between $e^+e^-$ and tau decay data cannot be explained by heavy new physics.

Introduces a new theoretical framework for studying non-standard interactions in tau decays.

Highlights the need for further investigation into the source of the discrepancy.

Abstract

We show the discrepancy between the isospin-rotated $e^+e^-\to\eta\pi^-\pi^+$ cross-section -- measured by various collaborations -- and the Belle $\tau^-\to\eta\pi^-\pi^0\nu_\tau$ spectrum, which cannot be explained by heavy new physics non-standard interactions. We give for the first time the framework needed to study these beyond the standard model contributions in three-meson tau decays.