Simplified formulation of unimodular gravity

Paper Title:

Unimodular Plebański Gravity

Published on:

12 September 2023

Primary Category:

General Relativity and Quantum Cosmology

Paper Authors:

Steffen Gielen,

Elliot Nash

Bullets

Key Details

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New unimodular Plebanski formulations presented, allowing varying cosmological constant

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Diffeomorphism symmetry broken by fixed volume form or new fields

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Classical equivalence to GR shown, applications in quantization discussed

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First-order and pure connection actions also obtained

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Minisuperspace model demonstrates new global degree of freedom

Explore the topics in this paper

chiral formulation

cosmological constant

minisuperspace

plebanski

unimodular gravity

AI generated summary

Simplified formulation of unimodular gravity

This paper presents new formulations of unimodular gravity, an alternative theory to general relativity where the cosmological constant arises as an integration constant rather than a fixed parameter. By using Plebanski's chiral formulation involving complex 2-forms and connections, the authors construct several unimodular gravity actions that mirror similar constructions in the metric formulation. These allow the cosmological constant to vary between solutions, break diffeomorphism symmetry, and provide a preferred volume form. Equivalence to general relativity at the classical level is discussed. Potential applications in constructing spinfoam models for quantization and a minisuperspace example are outlined.