  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.

High Energy Physics - Phenomenology