# Mesons with Beauty and Charm: New Horizons in Spectroscopy

## TL;DR

This paper explores the spectroscopy of $B_c^+$ mesons, which contain both charm and beauty quarks, offering insights into heavy quark interactions and testing theoretical models beyond existing quarkonium systems.

## Contribution

It provides new insights into the $B_c^+$ meson spectrum, highlighting its unique position between charmonium and bottomonium and discussing implications for heavy quark dynamics.

## Key findings

- $B_c^+$ mesons have a distinct spectrum between charmonium and bottomonium.
- The dynamics of $B_c^+$ are richer due to unequal quark masses.
- Spectrum analysis tests heavy quark interaction models.

## Abstract

The $B_c ^+$ family of $(c\bar{b})$ mesons with beauty and charm is of special interest among heavy quarkonium systems. The $B_c ^+$ mesons are intermediate between $(c\bar{c})$ and $(b\bar{b})$ states both in mass and size, so many features of the $(c\bar{b})$ spectrum can be inferred from what we know of the charmonium and bottomonium systems. The unequal quark masses mean that the dynamics may be richer than a simple interpolation would imply, in part because the charmed quark moves faster in $B_c$ than in the $J/\psi$. Close examination of the $B_c ^+$ spectrum can test our understanding of the interactions between heavy quarks and antiquarks and may reveal where approximations break down. ...