First-principles lattice-QCD decay constants for the Bc meson

Establish first-principles lattice-QCD determinations of the pseudoscalar and vector decay constants f_Bc and f_Bc* to provide model-independent benchmarks for competing descriptions of the short-distance Bc-meson dynamics.

Background

The paper predicts the pseudoscalar and vector Bc decay constants using a nonrelativistic Cornell potential model with one-loop QCD corrections. It emphasizes that these quantities probe the wave function at short quark–antiquark separations and are therefore sensitive to the treatment of short-distance dynamics, constituent-quark masses, and the strong coupling.

Existing theoretical predictions span a broad range, and the paper notes that no first-principles lattice-QCD calculation is currently available. Such calculations would provide a model-independent benchmark for assessing potential-model and QCD sum-rule predictions, including the paper’s values of f_Bc = 580 MeV and f_Bc* = 546 MeV.

References

No first-principles lattice-QCD determination of $f_{B_c}$ or $f_{B_c*}$ is currently available, so no model-independent benchmark exists --- this represents one of the most important outstanding problems in $B_c$ phenomenology and a priority target for lattice calculations.

— Spectroscopic parameters of $B_c$ meson  (2609.24536 - Küçükyılmaz et al., 21 Sep 2026) in Section 3.2, “Decay Constants” (subsection “Decay Constants”)