# Excited $\rho$ mesons in $B_{c}\to\psi^{(')}KK_{S}$ decays

## TL;DR

This paper analyzes exclusive $B_c$ decays to $J/a$ and $a(2S)$ with $KK_S$, highlighting the importance of excited $a$ mesons for decay descriptions and predicting observable resonance peaks.

## Contribution

It demonstrates the necessity of including excited $a$ mesons in decay models and provides theoretical predictions for branching fractions and mass distributions.

## Key findings

- Excited $a$ mesons significantly affect decay descriptions.
- Peaks from resonances are observable in $m_{KK_S}$ distributions.
- Predicted branching fractions and mass spectra are provided.

## Abstract

In the presented paper exclusive decays $B_{c}\to J/\psi KK_{S}$ and $B_{c}\to\psi(2S)KK_{S}$ are analyzed. It is shown that contributions of the excited $\rho$ mesons should be taken into account to describe these decays. It is also shown that, unlike the corresponding $\tau$ lepton decays, peaks in $m_{KK_{S}}$ distributions caused by these resonances are clearly seen and can be easily separated. Theoretical predictions for the branching fractions of the reactions and $m_{\psi K}$ distributions are also presented.