Imprint of the adjoint meson spectrum in the decay patterns of hidden-bottom tetraquarks

TL;DR

This paper investigates the decay patterns of hidden-bottom tetraquarks $Z_b$ and $Z_b^{'}$, linking their behavior to the degeneracy of adjoint mesons via lattice QCD and the Born-Oppenheimer Effective Field Theory.

Contribution

It provides the first evidence connecting tetraquark decay suppression to adjoint meson degeneracy using BOEFT and lattice QCD calculations.

Findings

Decay suppression of $Z_b^{'}$ explained by adjoint meson degeneracy.

$Z_b$ and $Z_b^{'}$ are superpositions of $Z_1$ and $Z_2$ tetraquark configurations.

Adjoint mesons associated with $Z_1$ and $Z_2$ are found to be degenerate.

Abstract

We aim to clarify the experimentally observed near-degeneracy and decay patterns of the isospin, $I=1$, hidden-bottom tetraquarks $Z_b(10610)$ and $Z_b(10650)$ with quantum numbers $J^{P}=1^{+}$.We refer to them as $Z_b$ and $Z_b^{'}$, respectively. In particular, we find first evidence that the suppression of the decay of $Z_b^{'}$ to $B\bar{B^*}$ can be understood in the context of the Born-Oppenheimer Effective Field Theory (BOEFT). BOEFT enables writing both $Z_b$ and $Z_b^{'}$ as superpositions of $Z_1$ and $Z_2$ tetraquark configurations. This decomposition naturally relates the decay patterns of $Z_b$ and $Z_b^{'}$ to the degeneracy of the light degrees of freedom associated with $Z_1$ and $Z_2$ tetraquarks, {\it i.e.,} $1^{--}$and $0^{-+}$ adjoint mesons, respectively. By calculating the adjoint meson correlators within the framework of lattice QCD, we get good indications that these adjoint mesons are degenerate.