Tetraquarks, Pentaquarks and Dibaryons in the large $N$ QCD

TL;DR

This paper investigates the properties and decay behaviors of multiquark hadrons such as tetraquarks, pentaquarks, and dibaryons in large $N$ QCD, revealing stability patterns and decay width behaviors as $N$ approaches infinity.

Contribution

It extends Witten's baryon picture to multiquark states in large $N$ QCD and analyzes their decay widths and stability, providing new insights into their observability.

Findings

Tetraquark decay widths remain constant as N increases.

Pentaquarks and dibaryons above certain thresholds have diverging decay widths.

Ground states are stable or narrow, while excited states above thresholds are unobservable.

Abstract

We study the multiquark hadrons in large $N$ QCD under the 't-Hooft limit, extending Witten's picture of the baryons. We explore the decay widths of tetraquarks, pentaquarks and dibaryons. Based on the decay behaviors, we point out in the $N\to \infty$ limit decay widths of tetraquarks stay constant, while those of pentaquarks and dibaryons above certain thresholds can diverge. In the large $N$ limit, we find that the ground states of the three spectroscopic series are stable or narrow and that the excited states of pentaquarks and dibaryons above the indicated thresholds are not observables. We compare our results with those obtained in a different large $N$ generalization of tetraquarks.