Energies of B_s meson excited states - a lattice study

TL;DR

This study uses lattice QCD simulations with dynamical fermions to analyze the energies of excited B_s meson states, focusing on higher angular momentum and radial excitations, and compares results to experimental data or predictions.

Contribution

It introduces improved hypercubic blocking in the time direction and provides detailed calculations of excited B_s meson states with spin-orbit splitting analysis.

Findings

Calculated energies of excited B_s meson states.

Observed spin-orbit splitting patterns.

Predicted positions of P-wave excited states.

Abstract

This is a follow-up to our earlier work on the energies and radial distributions of heavy-light mesons. The heavy quark is taken to be static (infinitely heavy) and the light quark has a mass about that of the strange quark. We now concentrate on the energies of the excited states with higher angular momentum and with a radial node. A new improvement is the use of hypercubic blocking in the time direction. The calculation is carried out with dynamical fermions on a 16 cubed times 32 lattice with a lattice spacing approximately 0.1 fm generated using a non-perturbatively improved clover action. In nature the closest equivalent of this heavy-light system is the B_s meson, which allows us to compare our lattice calculations to experimental results (where available) or to give a prediction where the excited states, particularly P-wave states, should lie. We pay special attention to the spin-orbit splitting, to see which one of the states (for a given angular momentum L) has the lower energy. An attempt is made to understand these results in terms of the Dirac equation.