Daria A. Tretyakova | Searcharxiv

arXiv2017

Stable black holes in shift-symmetric Horndeski theories

In shift-symmetric Horndeski theories, a static and spherically symmetric black hole can support linearly time-dependent scalar hair. However, it was shown that such a solution generically suffers from ghost or gradient instability in the vicinity of the horizon. In the present paper, we explore the possibility to avoid the instability, and present a new example of theory and its black hole solution with a linearly time-dependent scalar configuration. We also discuss the stability of solutions with static scalar hair for a special case where nonminimal derivative coupling to the Einstein tensor appears.

gr-qc↗

arXiv2016

Seeking for the observational manifestation of de Sitter Relativity

The de Sitter invariant special relativity is a natural extension of the usual Einstein special relativity. Within this framework a generalization of special relativity (SR) for the de Sitter space-time introduces a new length scale $R$, serving an origin of geometrical cosmological constant $Λ=3/R^2$. De Sitter relativity predicts the departure from the Lorentz invariance due to spacetime curvature, related to the geometrical cosmological constant. In this paper the possible impact of de Sitter special relativity effects on threshold particle processes and equivalence principle violation is considered. The main conclusion is that constraints, coming from cosmological fine structure constant variations render this effects nowadays undetectable. A brief outlook is given thereafter.

hep-ph↗