Heavy-light mesons beyond ladder approximation

TL;DR

This paper develops a new truncation scheme for Dyson-Schwinger equations to study heavy-light mesons, achieving accurate mass spectra and decay constants without additional parameters, improving upon previous approximations.

Contribution

Introduces a truncation scheme beyond the ladder approximation based on chiral symmetry, applicable to heavy-light mesons, with improved accuracy and simplicity.

Findings

Mass spectrum errors around 5% compared to experiments and lattice QCD.

Decay constants comparable to experimental and lattice results.

Scheme reduces discrepancies compared to equal spacing rule.

Abstract

The heavy-light mesons are studied within the framework of Dyson-Schwinger equations of QCD. Inspired by the axial-vector Ward-Takahashi identity resulting from the chiral symmetry, we propose a truncation scheme beyond the ladder approximation without introducing any additional parameter. For the pseudoscalar and vector heavy-light mesons, the obtained mass spectrum has the level of relative errors at $5\%$ compared with experimental data and lattice-QCD results. For the leptonic decay constants, our results are comparable with those from experiments and/or lattice QCD. For some channels, the discrepancies are sizable but significantly smaller than those using the equal spacing rule. The truncation scheme proposed in this work is simple and could be improved and applied to study other open flavor hadrons including both mesons and baryons.