A New Picture for the Formation and Decay of the Exotic $XY \! Z$ Mesons

TL;DR

This paper proposes a new dynamical model for the formation and decay of exotic $XY Z$ mesons, emphasizing confinement-induced hadronization of diquark-antidiquark pairs, explaining their narrow widths and decay preferences.

Contribution

It introduces a novel picture combining diquark models with experimental observations, explaining the formation, narrowness, and decay patterns of $XY Z$ states.

Findings

The model naturally explains the narrow widths of $XY Z$ states.

It accounts for the prompt production of these states.

It explains the decay preference to $ ext{ψ}(2S)$ over $J/ψ$.

Abstract

We present a new dynamical picture that identifies the formation of the exotic $\bar c c$-containing states $XY \! Z$ with the confinement-induced hadronization of a rapidly separating pair of a compact diquark and antidiquark. This picture combines the advantages of diquark-based models, which can accommodate much of the known $XY \! Z$ spectrum, with the experimental fact that such states are both relatively narrow and are produced promptly. It also naturally explains the preference of some of the exotic states to decay to $\psi(2S)$, rather than $J/\psi$, in terms of a simple wave-function overlap effect.