# Production of the $ X(3872)$ state via the $B^0 \to K^{\ast 0} X(3872)$ decay

## TL;DR

This paper estimates the production rate of the $X(3872)$ particle in $B^0$ decays using triangle mechanisms and molecular models, comparing results with experimental data to highlight the importance of charged components.

## Contribution

It introduces a novel calculation of the $X(3872)$ production via triangle mechanisms considering molecular structure, aligning theoretical predictions with experimental observations.

## Key findings

- The production rate depends on the coupling strength of charged components.
- The ratio of branching fractions aligns with experimental data.
- Charged components are crucial for accurate $X(3872)$ description.

## Abstract

In this work the production of the state $X(3872)$ is estimated via the reaction $B^0 \to K^{\ast 0} X(3872)$ through triangle mechanisms described by the sequence $B^0 \to D_s^{(*)+} (\to K^{\ast 0} D^{(*)+} ) \ D^{(*)-} \to K^{\ast 0} \ ( D^{(*)+} D^{(*)-} ) \to K^{\ast 0} X(3872) $. The molecular configuration $(D\bar D^* - c.c. )$ of the $X(3872)$ is considered. By means of the effective Lagrangian approach, the branching ratio $\mathcal{B}(B^0 \to K^{\ast 0} X(3872))$ is calculated as a function of the strength of the coupling of the charged components $(D^+\bar D^{*-} - c.c. )$ to the $X(3872)$ and compared with experimental data. Besides, employing the decay $B^0 \to K^{\ast 0} \psi (2S)$ as a normalization channel, the ratio of branching fractions $R = \frac{\mathcal{B}( B^0 \to K^{\ast 0} X(3872) )}{\mathcal{B}( B^0 \to K^{\ast 0} \psi (2S) )}\times \frac{\mathcal{B}( X(3872) \to J/\psi \pi^{+} \pi^{-} )}{\mathcal{B}( \psi (2S) \to J/\psi \pi^{+} \pi^{-} )} $ is also estimated. The findings provide another concrete example for the vital role of charged components in achieving a quantitatively correct description of the $X(3872)$.