$B_s^* B K$ vertex from QCD sum rules

TL;DR

This paper calculates the coupling constant of the $B_s^* B K$ vertex using QCD sum rules, considering different off-shell mesons and analyzing uncertainties to provide a precise estimate.

Contribution

The study introduces a comprehensive QCD sum rules analysis of the $B_s^* B K$ vertex, including multiple off-shell scenarios and uncertainty assessments.

Findings

Coupling constant $g_{B_s^* B K}=10.6 \, ext{±} \, 1.7$ obtained.

Different form factors converge to the same coupling value after extrapolation.

Uncertainty analysis enhances the reliability of the result.

Abstract

The form factors and the coupling constant of the $B_s^* B K$ vertex are calculated using the QCD sum rules method. Three point correlation functions are computed considering both $K$ and $B$ mesons off-shell and, after an extrapolation of the QCDSR results, we obtain the coupling constant of the vertex. We study the uncertainties in our result by calculating a third form factor obtained when the $B^*_s$ is the off-shell meson, considering other acceptable structures and computing the variations of the sum rules' parameters. The form factors obtained have different behaviors but their simultaneous extrapolations reach to the same value of the coupling constant $g_{B_s^* B K}=10.6 \pm 1.7$. We compare our result with other theoretical estimates.