Tadpole diagrams due to KK modes of graviton and radion do not contribute to the $ρ$ parameter

Abstract

In this brief report we show that tadpole diagrams due to KK modes of the graviton and radion do not contribute to the vectorial isospin breaking $ρ$ parameter. Our result is fairly general and it holds both for ADD and RS type scenarios. It shows that the difference between the results of different publications on this subject is not due to some of them not having considered tadpole diagrams in estimating the contribution to the $ρ$ parameter.