---
abstract: 'We have studied the production and decay of the $f_1(1285)$ into $\pi a_0(980)$ and $K^* \bar K$ as a function of the mass of the resonance and find a shoulder around 1400 MeV, tied to a triangle singularity, for the $\pi a_0(980)$ mode, and a peak around 1420 MeV with about 60 MeV width for the $K^* \bar K$ mode. Both these features agree with the experimental information on which the $f_1(1420)$ resonance is based. In addition, we find that if the $f_1(1420)$ is a genuine resonance, coupling mostly to $K^* \bar K$ as seen experimentally, one finds unavoidably about a 20% fraction for $\pi a_0(980)$ decay of this resonance, in drastic contradiction with all experiments. Altogether, we conclude that the $f_1(1420)$ is not a genuine resonance, but the manifestation of the $\pi a_0(980)$ and $K^* \bar K$ decay modes of the $f_1(1285)$ at higher energies than the nominal one.'
author:
- 'V. R. Debastiani'
- 'F. Aceti'
- 'Wei-Hong Liang'
- 'E. Oset'
title: 'Revising the $f_1(1420)$ resonance'
---

Introduction
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The $f_1(1420)$ resonance is catalogued in the Particle data book [@PDG] as an $I^G(J^{PC}) = 0^+(1^{++})$ state and has been observed in over 20 experiments. Its 