Compositeness and several applications to exotic hadronic states with heavy quarks

TL;DR

This paper applies multiple analytical methods to study the nature of recently discovered exotic hadronic resonances with heavy quarks, providing insights into their structure and composition.

Contribution

It introduces a comprehensive approach combining effective-range expansion, width saturation, compositeness, and data fitting to analyze heavy-quark exotic states.

Findings

Resonance structures analyzed with multiple methods.

Determined the compositeness of various exotic states.

Provided insights into the dynamical features of heavy-quark resonances.

Abstract

Several methods for studying the nature of a resonance are applied to resonances recently discovered in the bottonomium and charmonium sectors. We employ the effective-range expansion, the saturation of the width and compositeness of a resonance, as well as direct fits to data. The latter stem from generic $S$-matrix parameterization that account for relevant dynamical features associated to channels that couple strongly in an energy region around the resonance masses, in which their thresholds also lie. We report on results obtained with these methods for the resonances $Z_b(10610)$, $Z_b(10650)$, $Z_{cs}(3985)$, $Z_c(3900)$, $X(4020)$, $X(6900)$, $X(6825)$, and $P_{cs}(4459)$.