  Within the standard model (SM), the time dependent CP asymmetries in B -> psi
K_S, B -> eta' K_S and B -> phi K_S are expected to give the same result i.e.
sin (2 beta). However recent measurements of the mixing induced CP asymmetries
in B -> phi K_S and B -> eta' K_S modes give results whose central values
differ from SM expectations. We explore the effects of new physics in the two
Higgs doublet model (THDM), which allows tree level flavor changing neutral
currents (so called Model III), and the model with extra vector like down quark
(VLDQ). We find that the observed mixing induced CP asymmetry for B -> phi K_S
can not be accommodated by the THDM, but can be explained in the VLDQ model and
both models can explain the observed asymmetry for B -> eta' K_S mode.
