Rare decay $B\to X_s\nu \bar{\nu }$ in the two-Higgs-doublet model of type-III

In this paper, we calculated the new physics contribution to theoretically very clean rare decay $B\to X_s\nu \bar{\nu }$ in the general two-Higgs-doublet model (model III). Within the considered parameter space, we found that (a) the new physics contribution can provide one to two orders of enhancement to the branching ratio $\text{calb}(B\to X_s\nu \bar{\nu })$ and can saturate the experimental bound on $\text{calb}(B\to X_s\nu \bar{\nu })$ in some regions of the parameter space; (b) besides the CLEO data of $B \to X_s \gamma$,theALEPHupperlimiton$\calb (B \to X_s \nu \bar{\nu})$ also lead to further constraint on the size of the Yukawa coupling ${\lambda }_{tt}$: ${\lambda }_{tt}<6.4$ for ${\lambda }_{bb}=2.7$ and $\text{mhp}=200$ GeV.