Flavor Changing Fermion-Graviton Vertices

TL;DR

This paper analyzes flavor-changing quark-graviton interactions at one-loop level, revealing their properties, finiteness, and gauge invariance, with implications for massless and massive gravitons and potential extensions to leptons.

Contribution

It provides analytical expressions for flavor-changing quark-graviton form factors and explores their behavior for massless and massive gravitons, including long-range effects.

Findings

Form factors are finite and gauge-invariant.

Flavor-changing interactions are local for massless gravitons.

Massive gravitons induce long-range flavor-changing effects.

Abstract

We study the flavor-changing quark-graviton vertex that is induced at the one-loop level when gravitational interactions are coupled to the standard model. Because of the conservation of the energy-momentum tensor the corresponding form factors turn out to be finite and gauge-invariant. Analytical expressions of the form factors are provided at leading order in the external masses. We show that flavor-changing interactions in gravity are local if the graviton is strictly massless while if the graviton has a small mass long-range interactions inducing a flavor-changing contribution in the Newton potential appear. Flavor-changing processes with massive spin-2 particles are also briefly discussed. These results can be generalized to the case of the lepton-graviton coupling.