Semileptonic Bc decay within heavy quark spin symmetry

We calculate the semileptonic Bc decay widths using heavy quark spin symmetry. The form factors are estimated from the wave function model of Isgur, Scora, Grinstein and Wise (ISGW). We also discuss the extraction of |Vcs|/|Vcb|, |Vcs|/|Vcd| and |Vub|/|Vcs| from semileptonic Bc decays. The theoretical uncertainties are minimized when using the ratios of Bc differential decay rates to extract the ratios of CKM elements at zero recoil limit. The result is potentially important for extracting CKM elements from future measurements at LHC and SSC.