Exotic Charmonium and Bottomonium-like Resonances

TL;DR

This paper uses QCD Sum Rules to analyze new charmonium and bottomonium-like states, proposing that the $Z_b^+(10610)$ resonance is an excited tetraquark state similar to the X(3872).

Contribution

It introduces a novel interpretation of the $Z_b^+(10610)$ as an excited tetraquark, expanding understanding of exotic hadron structures.

Findings

Identifies $Z_b^+(10610)$ as a first excitation of a tetraquark.

Supports the tetraquark interpretation of certain bottomonium-like states.

Provides theoretical backing for the structure of recently observed resonances.

Abstract

Many new states in the charmonium and bottomonium mass region were recently discovered by the BaBar, Belle and CDF Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states. In particular we identify the recently observed bottomonium-like resonance $Z_b^+(10610)$ with the first excitation of the tetraquark $X_b(1^{++})$, the analogue of the X(3872) state in the charm sector.