We have studied the production and decay of the f1(1285) into πa0(980) and K∗Kˉ as a function of the mass of the resonance and find a shoulder around 1400 MeV, tied to a triangle singularity, for the πa0(980) mode, and a peak around 1420 MeV with about 60 MeV width for the K∗Kˉ mode. Both these features agree with the experimental information on which the f1(1420) resonance is based. In addition, we find that if the f1(1420) is a genuine resonance, coupling mostly to K∗Kˉ as seen experimentally, one finds unavoidably about a 20\% fraction for πa0(980) decay of this resonance, in drastic contradiction with all experiments. Altogether, we conclude that the f1(1420) is not a genuine resonance, but the manifestation of the πa0(980) and K∗Kˉ decay modes of the f1(1285) at higher energies than the nominal one.
@article{arxiv.1611.05383,
title = {Revising the $f_1(1420)$ resonance},
author = {V. R. Debastiani and F. Aceti and Wei-Hong Liang and E. Oset},
journal= {arXiv preprint arXiv:1611.05383},
year = {2017}
}