Exotic meson-meson molecules and compact four--quark states

TL;DR

This paper performs exact calculations of $QQar nar n$ states in charm and bottom sectors using nonrelativistic potentials, identifying a few stable candidates and analyzing their properties to distinguish between molecular and compact states.

Contribution

It provides a detailed, exact analysis of four-quark states in specific sectors, highlighting stable candidates and their characteristics, which is a novel contribution compared to previous predictions.

Findings

Few stable four-quark candidates identified.

Analysis distinguishes between molecular and compact states.

Decay modes of candidates are discussed.

Abstract

We present an exact calculation of $S$ and $P$ wave $QQ\bar n\bar n$ states using different standard nonrelativistic quark--quark potentials. We explore in detail the charm and bottom sectors looking for bound states that could be measured within existing facilities. Against the proliferation of four--quark states sometimes predicted in the literature, we found a small number of candidates to be stable. We analyze their properties in a trial to distinguish between compact and molecular states. Possible decay modes are discussed.