---
author:
- 'M. K. Volkov'
- 'A. A. Pivovarov'
- 'A. A Osipov'
date: '30 January 2018 / Revised version: date'
title: '$\tau \to f_1 (1285)\pi^{-} \nu_{\tau}$ decay in the extended Nambu – Jona-Lasinio model'
---

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Introduction {#intro}
============

The recent measurements of the branching fractions of three-prong $\tau$ decay modes made by BABAR Collaboration [@Lees12] contain important new results on the decay $\tau \to f_1(1285) \pi^{-} \nu_{\tau}$ providing confidence that the precise information on the corresponding invariant mass distributions will also soon become available. Together with the large data sets obtained on this mode in the past by BABAR [@Aubert08; @Aubert05] and CLEO [@Bergfeld97] Collaborations this calls for improved understanding of the theoretical description of the process. The main purpose of our paper is to make a step in this direction.

The $\tau \to f_1\,\pi^{-} \nu_{\tau}$ decay is driven by the hadronization of the QCD axial-vector currents involved. The details of this mechanism are not yet clearly understood due to poor knowledge of the QCD dynamics at low-energies. Indeed, the invariant mass of the $(f_1, \pi )$-system belongs to 