The study of light invisible particles in $B_c$ decays

TL;DR

This study investigates the potential for light invisible particles in $B_c$ meson decays, providing upper limit predictions for various decay channels based on effective operator analysis and experimental data.

Contribution

Introduces a method to predict $B_c$ decay rates involving light invisible particles using effective operators and experimental constraints from other mesons.

Findings

Upper limits of branching fractions are around $10^{-6}$ to $10^{-5}$ for certain decay channels.

The channel $B_c o D_s^{(*)} ext{ extbackslash}chi ext{ extbackslash}chi$ has the largest upper limit.

Decay modes involving other mesons are also analyzed with predicted upper limits.

Abstract

In this paper, we study the light scalar and pseudoscalar invisible particles in the flavor changing neutral current processes of the $B_c$ meson. Effective operators are introduced to describe the couplings between quarks and light invisible particles. The Wilson coefficients are extracted from the experimental results of the $B$ and $D$ mesons, which are used to predict the upper limits of the branching fractions of the similar decay processes for the $B_c$ meson. The hadronic transition matrix element is calculated with the instantaneously approximated Bethe-Salpeter method. The upper limits of the branching fractions when $m_\chi$ taking different values are presented. It is found that at some region of $m_\chi$, the channel $B_c\to D_s^{(\ast)}\chi\chi$ has the largest upper limit which is of the order of $10^{-6}$, and for $B_c\to D_s^\ast\chi\chi^\dagger$, the largest value of the upper limits can achieve the order of $10^{-5}$. Other decay modes, such as $B_c\to D^{(*)}\chi\chi^{(\dagger)}$ and $B_c\to B^{(*)}\chi\chi^{(\dagger)}$, are also considered.