Determination of the CKM matrix by semileptonic rare B-decays

The possibility to test the unitarity triangle of CKM matrix is examined by using the semileptonic rare $B$ decays, $B \rightarrow X_q \, \l^+ \, \l^-$ with $q = d, s$ and $\l$'s are leptons. The discussion is emphasized on the CP asymmetry in the framework of standard and beyond the standard models. For the beyond standard model, a minimal extension of the standard model containing an additional isosinglet charge (-1/3) charge quark, which leads to a deviation from CKM unitarity, is considered. As the results, in the standard model the CP asymmetry is visible only for $B \rightarrow X_d \, \l^+ \, \l^-$, while in the latter model it is sizeable even for $B \rightarrow X_s \, \l^+ \, \l^-$.