Gravity and the Neutral Currents: Effective Interactions from the Trace Anomaly

TL;DR

This paper analyzes the one graviton-two neutral gauge bosons vertex at one-loop level in the electroweak theory, revealing how the trace anomaly mediates interactions between gravity and the Standard Model, with implications for low-scale gravity models at the LHC.

Contribution

It provides a complete derivation of the effective interaction vertex involving gravity and neutral gauge bosons, including anomaly mediation and scalar sector improvements, at one-loop in the electroweak theory.

Findings

The trace anomaly mediates gravity-gauge interactions via effective scalar degrees of freedom.

Derived Ward and Slavnov-Taylor identities for the vertex.

Identified implications for low-scale gravity phenomenology at the LHC.

Abstract

We present a complete study of the one graviton-two neutral gauge bosons vertex at 1-loop level in the electroweak theory. This vertex provides the leading contribution to the interaction between the Standard Model and gravity, mediated by the trace anomaly, at first order in the inverse Planck mass and at second order in the electroweak expansion. At the same time, these corrections are significant for precision studies of models with low scale gravity at the LHC. We show, in analogy with previous results in the QED and QCD cases, that the anomalous interaction between gravity and the gauge current of the Standard Model, due to the trace anomaly, is mediated, in each gauge invariant sector, by effective massless scalar degrees of freedom. We derive the Ward and Slavnov-Taylor identities characterizing the vertex. Our analysis includes the contributions from the improvements of the scalar sector, induced by a conformally coupled Higgs sector in curved space.