Strong D* -> D+pi and B* -> B+pi couplings

TL;DR

This paper calculates the strong couplings g_{D* D pi} and g_{B* B pi} using Dyson-Schwinger equations, linking them to decay constants, and discusses heavy-quark mass effects on these couplings.

Contribution

It provides a unified, QCD-consistent calculation of heavy-light meson couplings and their relation to decay constants, highlighting the impact of heavy-quark mass corrections.

Findings

g_{D* D pi} = 15.9+2.1/-1.0

g_{B* B pi} = 30.0+3.2/-1.4

Heavy-quark corrections are significant for charm quarks.

Abstract

We compute g_{D* D pi} and g_{B* B pi} using a framework in which all elements are constrained by Dyson-Schwinger equation studies of QCD, and therefore incorporates a consistent, direct and simultaneous description of light- and heavy-quarks and the states they may constitute. We link these couplings with the heavy-light-meson leptonic decay constants, and thereby obtain g_{D* D pi}=15.9+2.1/-1.0 and g_{B* B pi}=30.0+3.2/-1.4. From the latter we infer \hat-g_B=0.37+0.04/-0.02. A comparison between g_{D* D pi} and g_{B* B pi} indicates that when the c-quark is a system's heaviest constituent, Lambda_{QCD}/m_c-corrections are not under good control.