Quantum corrections in massive bigravity and new effective composite metrics

TL;DR

This paper analyzes quantum corrections in massive bigravity, revealing destabilization of interactions at the quantum level and proposing new effective metrics for matter coupling with potential cosmological significance.

Contribution

It computes one-loop quantum corrections in bigravity and introduces novel effective composite metrics for matter coupling, addressing quantum stability issues.

Findings

Quantum interactions destabilize at the quantum level similar to massive gravity.

Broken diffeomorphism invariance influences quantum behavior.

New effective metrics may offer interesting phenomenology and cosmological implications.

Abstract

We compute the one-loop quantum corrections to the interactions between the two metrics of the ghost-free massive bigravity. When considering gravitons running in the loops, we show how the structure of the interactions gets destabilized at the quantum level, exactly in the same way as in its massive gravity limit. A priori one might have expected a better quantum behavior, however the broken diffeomorphism invariance out of the two initial diffeomorphisms in bigravity has similar consequences at the quantum level as the broken diffeomorphism in massive gravity. From lessons of the generated quantum corrections through matter loops we propose yet other types of effective composite metrics to which the matter fields can couple. Among these new effective metrics there might be one or more that could provide interesting phenomenology and important cosmological implications.