The $D^*D pi$ and $B^*Bpi$ couplings from light-cone sum rules

We revisit the calculation of the strong couplings $D^*Dpi$ and $B^*Bpi$ from the QCD light-cone sum rules using the pion light-cone distribution amplitudes. The accuracy of the correlation function, calculated from the operator product expansion near the light-cone, is upgraded by taking into account the gluon radiative corrections to the twist-3 terms. The double spectral density of the correlation function, including the twist-2, 3 terms at ${cal O} (alpha_s)$ and the twist-4 LO terms, is presented in an analytical form for the first time. This form allows us to use vario