Heavy-Meson Decay Constants: Isospin Breaking from QCD Sum Rules

TL;DR

This paper compares heavy-meson decay constants calculated via QCD sum rules and lattice QCD, highlighting agreement for D mesons but significant discrepancies for B mesons due to isospin breaking effects.

Contribution

It provides a comparative analysis of isospin breaking effects in heavy-meson decay constants from QCD sum rules versus lattice QCD, emphasizing differences between D and B mesons.

Findings

Agreement for D mesons between methods

Discrepancy by a factor of four for B mesons

Isospin breaking effects vary between meson types

Abstract

Compared with lattice QCD, isospin breaking of heavy-meson decay constants from QCD sum rules agrees for $D$ mesons but disagrees (by a factor of four) for $B$ mesons.