# Non-standard interactions in $\tau^- \to (\pi^-\eta,\pi^-\pi^0)\nu_{\tau}$ decays

## TL;DR

This paper investigates how semileptonic tau decays can constrain non-standard weak interactions, showing current data limits scalar and tensor NS interactions, with future experiments promising tighter bounds.

## Contribution

The study provides new constraints on non-standard scalar and tensor interactions in tau decays, highlighting the potential of upcoming measurements to improve these limits.

## Key findings

- Experimental data constrains NS scalar and tensor interactions.
- Future measurements at Belle II can tighten these constraints.
- Improved form factor knowledge enhances sensitivity to NS interactions.

## Abstract

Originally thought as clean processes to study the hadronization of the weak currents, semileptonic tau lepton decays can be useful to set constraints on non-standard (NS) weak interactions. In this talk we summarize our recent studies on the effects of NS interactions in $\tau^- \to (\pi^-\pi^0,\pi^-\eta)\nu_{\tau}$ decays. We find that experimental data on these decays provide strong constraints on NS scalar and tensor interactions, respectively. Further improved measurements at Belle II and a better knowledge of necessary tensor and scalar form factors will allow to set limits on these NS interactions that are similar or better to contraints obtained from other low-energy processes.