Relativistic corrections to the pair $B_c$-meson production in $e^{+}{e}^{-}$ annihilation

Relativistic corrections to the pair $B_c$-meson production in $e^{+}{e}^{-}$-annihilation are calculated. We investigate a production of pair pseudoscalar, vector and pseudoscalar+vector $B_c$-mesons in the leading order perturbative quantum chromodynamics and relativistic quark model. Relativistic expressions of the pair production cross sections are obtained. Their numerical evaluation shows that relativistic effects in the production amplitudes and bound state wave functions three times reduce nonrelativistic results at the center-of-mass energy s=22 GeV.