A determination of the CKM-matrix element ratio $|V_{ts} |/|V_{cb} |$ from the rare B-decays $B\to K^*+\gamma$ and $B\to X_s +\gamma$

Implications of the recent CLEO observation [1] of the rare decay mode $B→K^*+γ$ having a combined branching ratio BR($B→K^*+γ$)=(4.5±1.5±0.9)×10−5 and an improved upper limit on the inclusive branching ratio BR(B→Xs+γ)-108 GeV. Within the SM, we show that the resulting experimental upper limit can be interpreted as a corresponding limit on the CKM-matrix element ratio yielding $|V_{ts} |/|V_{cb} |$1.6×10−5 [1,2]. Combining the exclusive and inclusive decay rates, we determine 0.50≤|Vts|/|Vcb|≤1.67 (at 95% C.L.)