  We investigate the effect of the dimuon CP asymmetry from the B decay modes,
recently observed at 3.2 sigma deviation from the Standard Model (SM) by the D0
collaboration, in the context of SU(5) and SO(10) GUT models. We exhibit that a
large amount of flavor violation between the second and the third generation is
generated due to the large neutrino atmospheric mixing angle and this flavor
violation can be responsible for the observed large CP asymmetry due to the
presence of new phases (not present in the CKM matrix) in the Yukawa couplings.
We also study the implication of the parameter space in these GUT models with
large CP violating lepton asymmetry for different phenomenologies, e.g., Br(tau
-> mu + gamma), Br(B_s -> mu + mu) at the Fermilab, direct detection of dark
matter (DM) in the ongoing detectors and measurement of muon flux from solar
neutrinos at the IceCube experiment.
