B^-_c->\eta' \ell^- \bar{\nu} decay and lepton polarization asymmetry
  In this paper we study the lepton polarization asymmetry for the simileptonic OZI-forbidden annihilation B^-_c->\eta' \ell^- \bar{\nu} decay where \ell=\mu, \tau. Our results show that the branching ratio turn out to be of order 10^{-4}. Beside, we find that longitudinal, transversal and normal components of lepton polarizations can be measured for both \mu and \tau decay modes in the future experiments at the LHC. 
V. Bashiry