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Couplings between pion and charmed mesons

We compute the couplings $DD^*π$,$D_1D^*π$,$D^*D^*π$, $D_1 D_1π$ using QCD sum rules. These couplings are important inputs in the meson exchange model calculations used to estimate the amount of $J/ψ$ absorption due to pions and rho mesons in heavy ion collisions. Our sum rules are constructed at the first order in the pion momentum $p_μ$, 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 $g_{DD^*π}=8.2 \pm 0.1$, $g_{D_1 D^* π} = 15.8 \pm 2 {\rm GeV}$, $g_{D^* D^* π}= 0.3 \pm 0.03$ and $g_{D_1 D_1 π}= 0.17 \pm 0.04$.