Spin degeneracy in multi-hadron systems with a heavy quark

TL;DR

This paper demonstrates that spin degeneracy, a known phenomenon in single hadrons, extends universally to multi-hadron systems containing a single heavy quark, regardless of their internal structure.

Contribution

It generalizes the concept of spin degeneracy to multi-hadron systems with a heavy quark, including various exotic configurations, using effective theory analysis.

Findings

Spin degeneracy applies to multi-hadron systems with a heavy quark.

Universal phenomenon across different internal structures.

Demonstrated in specific hadronic systems like $P^{(*)}N$ states.

Abstract

We study multi-hadron systems with a single heavy quark (charm or bottom) in the limit of heavy quark mass. The spin degeneracy of the states with quantum numbers $(j+1/2)^{P}$ and $(j-1/2)^{P}$ for $j \neq 0$, known in a normal hadron, can be generalized to multi-hadron systems. The spin degeneracy is the universal phenomena for any multi-hadron systems with a single heavy quark, irrespective of their internal structures, including compact multi-quarks, hadronic molecules and exotic nuclei. We demonstrate the spin degeneracy in the hadronic systems formed by a heavy hadron effective theory; $P^{(\ast)}N$ states with a $P^{(\ast)}=\bar{D}^{(\ast)}$, $B^{(\ast)}$ meson and a nucleon $N$, and a $P^{(\ast)}$ meson in nuclear matter.