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Uninvited guest in mixed derivative Hořava gravity


Andrew Coates

Mattia Colombo

A. Emir

Professor of Gravitational Physics


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.


Coates, A., Colombo, M., Gümrükçüoğlu, A. E., & Sotiriou, T. P. (2016). Uninvited guest in mixed derivative Hořava gravity. Physical Review D, 94(8), Article 84014.

Journal Article Type Article
Acceptance Date Jun 1, 2016
Publication Date Oct 6, 2016
Deposit Date Dec 21, 2016
Publicly Available Date Dec 21, 2016
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0010
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 94
Issue 8
Article Number 84014
Public URL
Publisher URL
Additional Information ©2016 American Physical Society.


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