Compositeness of near-threshold exotic hadrons with decay and coupled-channel effects

TL;DR

This paper investigates the internal structure of near-threshold exotic hadrons, considering both molecular and elementary components, and examines how decay and coupled-channel effects influence their compositeness using effective field theory.

Contribution

It introduces a method to calculate the compositeness of near-threshold states accounting for decay and coupled-channel effects within an effective field theory framework.

Findings

Decay and coupled-channel effects modify the molecular dominance in near-threshold states.

Elementary components are not fully excluded in the structure of these hadrons.

The effective field theory approach provides a quantitative measure of compositeness.

Abstract

The near-threshold exotic hadrons such as $T_{cc}$ and $X(3872)$ are naively considered as the hadronic molecular state from the viewpoint of the low-energy universality. However, it is also known that the elementary dominant state is not completely excluded as the internal structure of the near-threshold states. Furthermore, the dominance of molecules is expected to be modified by the decay or coupled channels. We discuss these features of the near-threshold bound states by calculating the compositeness with the effective field theory.