Bcspectroscopy

In the framework of potential models for heavy quarkonium the mass spectrum for the system (b¯c) is considered. Spin-dependent splittings taking into account a change of a constant for the effective Coulomb interaction between the quarks, and widths of radiative transitions between the (b¯c) levels are calculated. In the framework of QCD sum rules, the masses of the lightest vector ${\mathit{B}}_{\mathit{c}}^{\mathrm{*}}$ and pseudoscalar ${\mathit{B}}_{\mathit{c}}$ states are estimated, the scaling relation for leptonic constants of heavy quarkonia is derived, and the leptonic constant ${\mathit{f}}_{\mathit{B}\mathit{c}}$ is evaluated.