The implementation of the heavy quark spin symmetry in possible molecular states at the mixed bottom-charm threshold is somewhat different from that at the open charm or bottom thresholds. In particular it depends on two parameters describing separately the symmetry for the bottom and for charmed quarks. The corresponding spin structures of the S-wave molecular states of the meson pairs B(∗)D(∗) are discussed as well as their consequences for properties of possible near-threshold resonances, analogs of the known charmoniumlike and bottomoniumlike X and Z states.
Bibliographical noteFunding Information:
This work is supported in part by U.S. Department of Energy Grant No. DE-SC0011842.
© 2018 authors. Published by the American Physical Society.