Uninvited guest in mixed derivative Hořava gravity

Coates, Andrew and Colombo, Mattia and Gümrükçüoğlu, A. Emir and Sotiriou, Thomas P. (2016) Uninvited guest in mixed derivative Hořava gravity. Physical Review D, 94 (8). 84014/1-84014/12. ISSN 2470-0010

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Abstract

We revisit the mixed-derivative extension of Hořava gravity which was designed to address the naturalness problems of the standard theory in the presence of matter couplings. We consider the minimal theory with mixed-derivative terms that contain two spatial and two temporal derivatives. Including all terms compatible with the (modified) scaling rules and the foliation-preserving diffeomorphisms, we calculate the dispersion relations of propagating modes. We find that the theory contains four propagating degrees of freedom, as opposed to three in the standard Hořava gravity. The new degree of freedom is another scalar graviton, and it is unstable at low energies. Our result brings tension to the Lorentz-violation suppression mechanism that relies on separation of scales.

Item Type: Article
Additional Information: ©2016 American Physical Society.
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Mathematical Sciences
University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: https://doi.org/10.1103/PhysRevD.94.084014
Depositing User: Eprints, Support
Date Deposited: 21 Dec 2016 13:51
Last Modified: 19 Jan 2017 16:58
URI: http://eprints.nottingham.ac.uk/id/eprint/39497

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