All Outputs (49)

Causality and black holes in spacetimes with a preferred foliation (2016)
Journal Article
Bhattacharyya, J., Colombo, M., & Sotiriou, T. P. (2016). Causality and black holes in spacetimes with a preferred foliation. Classical and Quantum Gravity, 33(23), Article 235003. https://doi.org/10.1088/0264-9381/33/23/235003

© 2016 IOP Publishing Ltd. We develop a framework that facilitates the study of the causal structure of spacetimes with a causally preferred foliation. Such spacetimes may arise as solutions of Lorentz-violating theories, e.g. Horava gravity. Our fra... Read More about Causality and black holes in spacetimes with a preferred foliation.

Uninvited guest in mixed derivative Hořava gravity (2016)
Journal Article
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. https://doi.org/10.1103/PhysRevD.94.084014

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... Read More about Uninvited guest in mixed derivative Hořava gravity.

Extrinsic curvature in two-dimensional causal dynamical triangulation (2016)
Journal Article
Glaser, L., Sotiriou, T. P., & Weinfurtner, S. (2016). Extrinsic curvature in two-dimensional causal dynamical triangulation. Physical Review D, 94(6), Article 64014. https://doi.org/10.1103/PhysRevD.94.064014

Causal dynamical triangulation (CDT) is a nonperturbative quantization of general relativity. Hořava-Lifshitz gravity, on the other hand, modifies general relativity to allow for perturbative quantization. Past work has given rise to the speculation... Read More about Extrinsic curvature in two-dimensional causal dynamical triangulation.

Low energy ghosts and the Jeans’ instability (2016)
Journal Article
Gümrükçüoğlu, A. E., Mukohyama, S., & Sotiriou, T. P. (2016). Low energy ghosts and the Jeans’ instability. Physical Review D, 94(6), Article 64001. https://doi.org/10.1103/PhysRevD.94.064001

We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar’s gradient is spacelike. By performing a canonical transformation we demonstra... Read More about Low energy ghosts and the Jeans’ instability.

Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity (2016)
Journal Article
Bhattacharyya, J., Coates, A., Colombo, M., & Sotiriou, T. P. (2016). Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity. Physical Review D, 93(6), Article 64056. https://doi.org/10.1103/PhysRevD.93.064056

We compare the initial value formulation of the low-energy limit of (nonprojectable) Hořava gravity to that of Einstein-æther theory when the æther is assumed to be hypersurface orthogonal at the level of the field equations. This comparison clearly... Read More about Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity.

Slowly rotating black holes in Einstein-æther theory (2016)
Journal Article
Barausse, E., Sotiriou, T. P., & Vega, I. (2016). Slowly rotating black holes in Einstein-æther theory. Physical Review D, 93(4), Article 44044. https://doi.org/10.1103/PhysRevD.93.044044

We study slowly rotating, asymptotically flat black holes in Einstein-æther theory and show that solutions that are free from naked finite area singularities form a two-parameter family. These parameters can be thought of as the mass and angular mome... Read More about Slowly rotating black holes in Einstein-æther theory.

Ho?ava gravity with mixed derivative terms: powercounting renormalizability with lower order dispersions (2015)
Journal Article
Colombo, M., Gümrükçüoğlu, A. E., & Sotiriou, T. P. (2015). Hořava gravity with mixed derivative terms: powercounting renormalizability with lower order dispersions. Physical Review D - Particles, Fields, Gravitation and Cosmology, 92(6), Article 064037. https://doi.org/10.1103/PhysRevD.92.064037

It has been argued that Hořava gravity needs to be extended to include terms that mix spatial and time derivatives in order to avoid unacceptable violations of Lorentz invariance in the matter sector. In an earlier paper we have shown that including... Read More about Ho?ava gravity with mixed derivative terms: powercounting renormalizability with lower order dispersions.

Multipole moments in scalar-tensor theory of gravity (2015)
Journal Article
Pappas, G., & Sotiriou, T. P. (2015). Multipole moments in scalar-tensor theory of gravity. Physical Review D - Particles, Fields, Gravitation and Cosmology, 91, 1-12. doi:10.1103/PhysRevD.91.044011

Stationary, asymptotically flat spacetimes in general relativity can be characterized by their multipole moments. The moments have proved to be very useful tools for extracting information about the spacetime from various observables and, more recent... Read More about Multipole moments in scalar-tensor theory of gravity.

Black hole hair in generalized scalar-tensor gravity (2014)
Journal Article
Sotiriou, T., & Zhou, S. (2014). Black hole hair in generalized scalar-tensor gravity. Physical Review Letters, 112(25), doi:10.1103/PhysRevLett.112.251102

The most general action for a scalar field coupled to gravity that leads to second-order field equations for both the metric and the scalar—Horndeski’s theory—is considered, with the extra assumption that the scalar satisfies shift symmetry. We show... Read More about Black hole hair in generalized scalar-tensor gravity.