We compute the couplings $DD^*\pi$,$D_1D^*\pi$,$D^*D^*\pi$, $D_1 D_1\pi$ using QCD sum rules. These couplings are important inputs in the meson exchange model calculations used to estimate the amount of $J/\psi$ absorption due to pions and rho mesons in heavy ion collisions. Our sum rules are constructed at the first order in the pion momentum $p_\mu$, which give the couplings that are not trivially related to the soft-pion theorem. Our calculated couplings, which somewhat depend upon the values of the heavy meson decay constants, are $g_{ DD^*\pi}=8.2 \pm 0.1$, $g_{ D_1 D^* \pi} = 15.8 \pm 2 { \rm GeV}$, $g_{ D^* D^* \pi}= 0.3 \pm 0.03$ and $g_{ D_1 D_1 \pi}= 0.17 \pm 0.04$.
Categories: hep-ph nucl-th