Triangle relations for XY Z states

Abstract

We propose novel triangle relations, not the well-known triangle singularity, for better understanding of the exotic [Formula: see text] states. Nine [Formula: see text] resonances, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] have been classified into triples to construct three triangles based on the assumption that they are all tetra-quark states. Here [Formula: see text] has not been observed experimentally yet, and we predict its mass and roughly the width. We also suggest some channels deserving search for with high priority based on this hypothesis, as well as predictions of a few production/decay rates of these channels. We hope further experimental studies of the [Formula: see text] states will benefit from our results.