Highly excited $B$, $B_s$ and $B_c$ meson spectroscopy from lattice QCD

TL;DR

This lattice QCD study computes the excited state spectra of $B$, $B_s$, and $B_c$ mesons, revealing a rich spectrum including hybrid states, and compares results with experimental data to enhance understanding of heavy meson spectroscopy.

Contribution

The paper provides the first detailed lattice QCD computation of excited $B$, $B_s$, and $B_c$ meson spectra, including hybrid states, using a large operator basis and relativistic actions.

Findings

Identified hybrid-like states approximately 1500 MeV above ground states.

Achieved good agreement with experimental results for known states.

Mapped excited states up to $J=4$ matching quark model patterns.

Abstract

Excited state spectra of $B$, $B_s$ and $B_c$ mesons are computed using lattice QCD. Working with a large basis of carefully constructed, approximately-local $q\bar{q}$-like operators we determine a rich spectrum of states up to $J=4$ in $B, B_s$ and $B_c$, that can be grouped into patterns matching those of the quark model. In addition, hybrid-like states are identified at approximately 1500 MeV above the ground states in each of $B, B_s$ and $B_c$, in a multiplet pattern already found in similar computations at a range of quark masses spanning light to bottom. This study is performed using an anisotropic, relativistic Wilson-clover action at a single spatial lattice spacing of $a_s\approx 0.12$ fm and with a light-quark mass corresponding to $m_\pi\approx 391$ MeV. We find good agreement with experimental results where known and discuss prospects for further work in interesting $J^P$ quantum numbers.