Penguin-diagram-induced B-->KX phi decays in the standard model and in the two-Higgs-doublet model.

We systematically analyse the gluonic penguin-induced charmless decays B → KXφ(KX denotes the meson state sq (q = u or d) ), in the standard model and the two-Higgsdoublet model. These processes, being induced at one-loop level, are of great importance in measuring the virtual top quark effect in the standard model, and also in searching for the non-standard signals in the low energy region. It is shown that the QCD effect is also significant in these processes, as in the weak radiative processes B → Xsγ. We also show that the charged Higgs contribution can not provide sizable enhancements for the decays B → KXφ, in contrast to the decays B → KXγ. It is also found that processes such as B → K1(1400)φ and B → K(1460)φ have large branching fractions among B → KXφ decays. E-mail:[email protected]