Meson loops and the $g_{D^{\ast }D\pi }$ coupling

Abstract

The $D^{\ast }D\pi$ form factor is evaluated at low and moderate $Q^2$ in a hadronic loop model, for off-shell $D$ mesons. The results contain arbitrary constants, which are fixed so as to match previous QCD sum rule calculations valid at higher $Q^2$. The form factor obtained in this way was used to extract the coupling constant, which is in very good agreement with the experimental value.

Comments: 8 pages, RevTex, 6 eps figures