# $a_1$ properties in hadronic tau decays

## TL;DR

This paper investigates the properties of the $a_1$ meson in hadronic tau decays, analyzing how the resonance-like structure manifests in different processes and its relation to pion interactions.

## Contribution

It provides a detailed analysis of the $a_1$ resonance in tau decays, focusing on the interactions between pions and the resonance's process-dependent properties.

## Key findings

- The $a_1$ resonance shows process-dependent properties in tau decays.
- Interactions between pion pairs influence the $a_1$ resonance structure.
- The analysis clarifies the role of two-body interactions in the $a_1$ meson.

## Abstract

Hadronic tau decays belong to the processes that show a resonance-like structure in the axial vector current in the $1-2$ GeV range. This structure, often denoted as the $a_1$ meson, seems to show different properties in different processes. The process $\tau\rightarrow 3\pi\nu_{\tau}$ allows for a clean separation of weak and strong effects and a clear production mechanism. We examine how this structure can be related to interactions between the three pions that emerge in the final state. In particular we start from the interactions between all two body combinations.