The Pattern of Exotic Hidden-Heavy Hadrons Revealed

TL;DR

This paper proposes a simple QCD-based model using the Born-Oppenheimer approximation to explain the pattern and properties of exotic hidden-heavy hadrons, resolving a long-standing theoretical puzzle.

Contribution

It introduces a novel application of the Born-Oppenheimer approximation to describe exotic heavy hadrons as bound states and resonances in specific potentials, clarifying their proximity to thresholds.

Findings

Explains the near-threshold placement of exotic hadrons.

Identifies which thresholds support bound states or resonances.

Accounts for the limited number of predicted exotic states.

Abstract

For more than twenty years, theory has failed to explain the pattern of the exotic heavy hadrons. We illustrate a simple solution to this longstanding puzzle using the Born-Oppenheimer approximation for QCD. Exotic hidden-heavy hadrons are bound states and resonances in potentials that are repulsive at short range and cross a heavy-hadron--pair threshold before approaching it. This explains the proximity of the exotic hidden-heavy hadrons to heavy-hadron--pair thresholds, identifies the thresholds that support bound states or resonances, and prevents an explosion in the number of predicted states. We also discuss the fine tunings of QCD that are responsible for the remarkable properties of some of the exotic hidden-heavy mesons.