  Many extensions of the Standard Model(SM) generate contributions to Flavor
Changing Neutral Current(FCNC) processes that must have sufficient flavor
suppression to be consistent with experiments, if the new physics (NP) is
associated with a scale of a TeV. Here we present a mechanism for suppressing
the NP effects to FCNC processes. We consider the possibility that the source
of NP contributions to FCNC processes share the same flavor symmetry underlying
the SM source of FCNC processes which are the quark and lepton mass matrices.
We call this the principle of shared flavor symmetry. In the flavor symmetric
limit, the quark and lepton mixing matrices have fixed forms and there are no
NP FCNC processes. In the flavor symmetric limit, we take the quark mixing
matrix to be the identity matrix and the lepton mixing matrix to be given by
tri-bimaximal mixing. Realistic mixing matrices are obtained by the small
breaking of the flavor symmetry. New contributions to FCNC processes arise
because of non universal breaking of the flavor symmetry in the quark and
lepton mass matrices and the NP sources of FCNC processes. In particular, we
will focus on new FCNC effects that arise due to the breaking of flavor
symmetry only in the quark and charged lepton mass matrices but not in the NP
sector. In this scenario, NP contributions to FCNC processes is linked to the
source of flavor symmetry breaking in the quark and charged lepton mass
matrices. To demonstrate the mechanism we use a two higgs doublet model as an
example of beyond the SM physics though one should be able to adapt this
mechanism to other models of new physics.
