# $B_c$ Spectroscopy from Lattice QCD

## TL;DR

This paper reports the first lattice QCD calculations of $B_c$ meson spectroscopy using NRQCD, including spin interactions and excited states, providing precise hyperfine and fine structure measurements.

## Contribution

It introduces a novel lattice NRQCD approach to $B_c$ spectroscopy with detailed treatment of spin effects and excited states, improving accuracy over previous methods.

## Key findings

- Accurate $S$ state hyperfine splitting values
- Detailed $P$ state fine structure measurements
- Inclusion of $^1P_1/^3P_1$ mixing effects

## Abstract

We present first results for $B_c$ spectroscopy using Lattice Non-Relativistic QCD (NRQCD). For the NRQCD action the leading order spin-dependent and next to leading order spin-independent interactions have been included with tadpole-improved coefficients. We use multi-exponential fits to multiple correlation functions to extract ground and excited $S$ states and give accurate values for the $S$ state hyperfine splitting and the P state ($B^{**}_c$) fine structure, including the effects of $^1P_1/^3P_1$ mixing.