Investigations on the weak decays of $D\bar{B}$ molecules

TL;DR

This paper investigates the weak decay mechanisms of a $Dar{B}$ molecular tetraquark state, predicting observable decay channels and branching ratios to aid future experimental detection.

Contribution

It proposes a decay mechanism for the $bcar{q}ar{q}$ tetraquark as a $Dar{B}$ molecule based on $T_{cc}$ decay models, highlighting potential observable decay modes.

Findings

Branching fraction for $Dar{B}$ decay into $^+ K^{-} ar{B}^0$ is sizable.

Decay proceeds via Cabibbo-favored weak decays of $ar{B}$ or $D$ mesons.

Identifies promising channels for experimental observation of the $Dar{B}$ molecule.

Abstract

The decays of exotic states discovered experimentally always proceed via the strong and electromagnetic interactions. Recently, a tetraquark state with the quark content $bc\bar{q}\bar{q}$ was predicted by Lattice QCD simulations. It is below the mass threshold of $D\bar{B}$, which can only decay via the weak interaction. In this work, based on the decay mechanism of $T_{cc}$ as a $DD^*$ molecule, we propose that the decays of the $bc\bar{q}\bar{q}$ tertaquark state as a $D\bar{B}$ molecule proceed via the Cabibbo-favored weak decays of the $\bar{B}$ or $D$ meson, accompanied by the tree-level decay modes and the triangle decay modes. Our results indicate that the branching fraction of the $D\bar{B}$ molecule decaying into $\pi^+ K^{-} \bar{B}^0$ is sizable, which is a good channel to observe the $D\bar{B}$ molecule in future experiments.