Phase effect of a general two-Higgs-doublet model inb→sγ

In a general two-Higgs-doublet model (2HDM), without the ad hoc discrete symmetries to prevent tree-level flavor-changing-neutral currents, an extra phase angle in the charged-Higgs-fermion coupling is allowed. We show that the charged-Higgs amplitude interferes destructively or constructively with the standard model amplitude for $\overrightarrow{b}s\gamma$ depending crucially on this phase angle. The popular models I and II are special cases of our analysis. As a result of this phase angle the severe constraint on the charged-Higgs-boson mass imposed by the inclusive rate of $\overrightarrow{b}s\gamma$ from CLEO can be relaxed. We also examine the effects of this phase angle on the neutron electric dipole moment. Furthermore, we also discuss other constraints on the charged-Higgs-fermion couplings coming from measurements of $B^0-B^0$ mixing, ${\rho }_0,$ and $R_b.$