$D^* D \pi$ and $B^* B \pi$ couplings from Dyson-Schwinger equations framework

Abstract

Employing a unified Dyson-Schwinger/Bethe-Salpeter equations approach, we calculate the strong decay couplings $D^* D \pi$ and $B^* B \pi$ within the so-called impulse-approximation in the moving frame. The $B^* B \pi$ estimation is reported for the first time based on a Poincar\'e invariant computation of the associated Bethe-Salpeter amplitudes. Our predictions yield $g_{D^* D \pi}=16.22_{-0.01}^{+0.03}$ and $g_{B^* B \pi}=40.09_{-1.37}^{+1.51}$, along with corresponding static strong couplings of $\hat{g}_D=0.55_{-<0.01}^{+<0.01}$, $\hat{g}_B=0.50_{-0.02}^{+0.02}$, which are consistent with recent experimental and lattice data.