TeV Particle Astrophysics 2017 (TeVPA 2017)

Failures of homogeneous and isotropic cosmologies in Extended Quasi-Dilaton Massive Gravity

9 Aug 2017, 16:45

15m

Spartan Room (The Athenaeum)

Oral Cosmology (incl. neutrino mass/number density) Cosmology

Speaker

Mr Saurabh Kumar (Case Western Reserve University)

Description

We analyze the Extended Quasi-Dilaton Massive Gravity model around a Friedmann-Lemaitre-Robertson-Walker cosmological background. We present a careful stability analysis of asymptotic fixed points. We find that the traditional fixed point cannot be approached dynamically, except from a perfectly fine-tuned initial condition involving both the quasi-dilaton and the Hubble parameter. A less-well examined fixed-point solution, where the time derivative of the 0-th Stuckelberg field vanishes ${\dot{\varphi }}^0=0$, encounters no such difficulty, and the fixed point is an attractor in some finite region of initial conditions. We examine the question of the presence of a Boulware-Deser ghost in the theory. We show that the additional constraint which generically allows for the elimination of the Boulware-Deser mode is $\mathit{\text{only}}$ present under special initial conditions. We find that the only possibility corresponds to the traditional fixed point, and the initial conditions are the same fine-tuned conditions that allow the fixed point to be approached dynamically.

Statement of Acknowledgement: This presentation was made possible, in part, through financial support from the School of Graduate Studies at Case Western Reserve University.

Presentation materials

Saurabh_Kumar.pdf

Saurabh_Kumar.pptx