Interactions between two heavy mesons within heavy meson chiral effective field theory

We have studied the interactions between two heavy mesons ($D^{(*)}$-$D^{(*)}$, $bar D^{(*)}$-$bar D^{(*)}$, $B^{(*)}$-$B^{(*)}$, or $bar B^{(*)}$-$bar B^{(*)}$) within heavy meson chiral effective field theory and investigated possible molecular states. The effective potentials are obtained with Weinbergs scheme up to one-loop level. At the leading order, four body contact interactions and one pion exchange contributions are considered. In addition to two pion exchange diagrams, we include the one-loop chiral corrections to contact terms and one pion exchange diagrams at the next-to-leading order. The effective potentials both in momentum space and coordinate space are investigated and discussed extensively. The possible molecular states are also studied and the binding energies are provided by solving the Schrodinger equation. The results will be helpful for the experimental search for the doubly-heavy molecular states.