V. FLAVOR CHANGING NEUTRAL CURRENTS : b → sγ It might be challenging to explain b → sγ with m ± H = 80 GeV as the lower mass bound on the charged Higgs is about 250 GeV if only the charged Higgs contribution is taken into account. In the MSSM, light stop is also natural and can be responsible for the cancelation of charged Higgs contribution. 2 σ range of b → sγ is obtained from the cancelation of the charged Higgs loop with the stop-chargino loop. At first glance, b → sγ observable is not dramatically changed in BMSSM framework. The reason is that Higgs sector, especially Higgs cubic and quartic couplings, suffers from considerable modification but chargino and squark sectors do not. However, such BMSSM operators can modify higgsino operators and then modify chargino and neutralino mixing. Futhermore, squark mixing is also changed by superpotential modification by ϵ$_{1}$ operator. In most natural case, stop and chargino masses are also as light as Higgs masses, and small modification to Higgsino sector could be important for b → sγ observable. BMSSM modification to chargino sector is given in chargino mass matrix Stop mass matrix is given by Consequently, chargino and stop mixing matrices are also changed. ϵ$_{1}$ term changes super- symmetric µ term as Therefore, we can have effectively large higgsino mass and large stop mixing for small tan β case in which we are interested. If M$_{2}$ ∼ µ ∼ 100GeV and ϵ$_{1}$ ∼ 0 . 1, supersymmetric µ term can be enhanced 20-30% for 1 ≲ tan β ≲ 2 and then ϵ$_{1}$ contribution could modify b → sγ observable. Numerical result is shown in fig. 5. The thick black line at 4 . 7 × 10 − 4 is the 2 σ bound. Only the left part from the thick black line is consistent with the measured branching ratio of b → sγ . In this case the lightest 15 µ → µ + ϵ$_{1}$ µ v $^{2}$sin 2 β. (20) m 2 ˜ t =   m 2 Q$_{3}$ + m 2 t + Δ$_{u}$ m$_{t}$ ( A$_{t}$ − µ cot β ) m$_{t}$ ( A$_{t}$ − µ cot β ) m 2 ¯ u$_{3}$ + m 2 t + Δ$_{¯}$ u   − 2 m$_{t}$ ϵ$_{1}$ µ v $^{2}$cos2 β   0 1 1 0$^{}$ $_{}$. (19) X =   M$_{2}$ √ 2 M$_{W}$ sin β √ 2 M$_{W}$ cos β µ  $_{}$+ ϵ$_{1}$ µ v $^{2}$sin 2 β   0 0 0 1$^{}$ $_{}$. (18)