Bimetric Gravity From Adjoint Frame Field In Four Dimensions

TL;DR

This paper introduces a new four-dimensional gravity model based on adjoint frame fields, describing a complex metric that interacts with two real metrics, leading to novel black hole and cosmological solutions.

Contribution

It presents a novel bimetric gravity model using adjoint frame fields, with solutions including black holes with hair and de Sitter space without a cosmological constant.

Findings

Black hole solutions with additional hair including Schwarzschild as a special case

De Sitter solutions realized without a cosmological constant

Spontaneous Lorentz symmetry breaking localized to the second metric

Abstract

We provide a novel model of gravity by using adjoint frame fields in four dimensions. It has a natural interpretation as a gravitational theory of a complex metric field, which describes interactions between two real metrics. The classical solutions establish three appealing features. The spherical symmetric black hole solution has an additional hair, which includes the Schwarzschild solution as a special case. The de Sitter solution is realized without introducing a cosmological constant. The constant flat background breaks the Lorentz invariance spontaneously, although the Lorentz breaking effect can be localized to the second metric while the first metric still respects the Lorentz invariance.