Review of phenomenological analyses of $η^{(\prime)} π$ resonances

Abstract

We present a robust analysis of the $η^{(\prime)} π$ system in COMPASS data. We fit the extracted relative phases and intensities with a coupled-channel formalism enforcing both unitarity and analyticity. We provide a robust extraction of a single exotic $π_1(1600)$ decaying to both $η^{(\prime)} π$ final states, and the resonance parameters of the $a_2(1320)$ and $a'_2(1700)$. We find no evidence for a second exotic state, which is compatible with recent Lattice QCD estimates.

Proceedings of the XIIIth Quark Confinement and the Hadron Spectrum conference, 31 July-6 August, 2018. Maynooth University, Ireland