Possible S -wave bound-states of two pseudoscalar mesons

Using the potentials derived from vector-meson-exchanges, the KK̄, $DK$, BK̄, DD̄, BB̄, $BD$, D̄K, $BK$ and BD̄ systems are studied. Possible S-wave bound-states of two pseudoscalar mesons are discussed. We find that systems of $DB$, DD̄, BB̄ and $DK$ with isospin 0 are likely to form S-wave bound states via strong interactions while the others are unlikely to be bound by the strong interaction sector alone. With the Coulomb potential, the K⁺K^- system can form an atomic bound state - the kaonium. The influence of the one-meson-exchange potential on the ground-state energy of the kaonium and its decay widths to ππ and πη are evaluated.