Heavy particle non-decoupling in flavor-changing gravitational interactions

The flavor-changing gravitational process, d to s + graviton, is evaluated at the one-loop level in the standard electroweak theory. We show that there exist non-decoupling effects of the internal heavy top quark in interactions with gravity. This non-decoupling phenomenon is explained by the fact that the coupling of quarks to the unphysical scalar field in the electroweak theory is proportional to the quark masses. The results we present in the 't Hooft-Feynman gauge are valid for on- and off-shell quarks and for all external and internal quark masses. The renormalized and unrenormalized two- and three-poit functions are shown to satisfy the same Ward-Takahashi identity. A diffeomorphism invariant effective Lagrangian in the large top quark mass limit is worked out and is shown to describe the graviton emitting process d to s + graviton, as well as the self-energy type d to s transition process. Among the subleading non-decoupling terms, we sort out those that can be regarded as due to the effective Lagrangian analogous in form to the Pauli term in quantum electrodynamics.