Quantum Cosmology in $(1+1)$-dimensional Ho\v{r}ava-Lifshitz theory of gravity

TL;DR

This paper quantizes a (1+1)-dimensional Hořava-Lifshitz cosmological model with a perfect fluid, revealing quantum effects that smooth out the big bang singularity and connecting to Liouville quantum mechanics for specific fluid equations of state.

Contribution

It advances understanding of (1+1)-dimensional HL cosmology by quantizing the model with a perfect fluid using Schutz formalism and Dirac's algorithm, analyzing the resulting Schrödinger equation.

Findings

Quantum theory smooths out the big bang singularity.

For w=1, potential resembles Liouville quantum mechanics.

Explicit solutions found for specific equations of state.

Abstract

In a recent paper [Phys. Rev. D 92:084012, 2015], the author studied the classical $(1+1)$-dimensional Friedmann-Robertson-Walker (FRW) universe filled with a perfect fluid in Ho\v{r}ava-Lifshitz (HL) theory of gravity. This theory is dynamical due to the anisotropic scaling of space and time. It also resembles the Jackiw-Teitelboim model, in which a dilatonic degree of freedom is necessary for dynamics. In this paper, I will give one step further in the understanding of (1+1)-dimensional HL cosmology by means of the quantization of the FRW universe filled with a perfect fluid with equation of state (EoS) $p=w\rho$. The fluid will be introduced in the model via Schutz formalism and Dirac's algorithm will be used for quantization. It will be shown that the Schr\"odinger equation for the wave function of the universe has the following properties: for $w=1$ (radiation fluid), the characteristic potential will be exponential, resembling Liouville quantum mechanics; for $w\neq 1$, a characteristic inverse square potential appears in addition to a regular polynomial which depends on the EoS. Explict solutions for a few cases of interesting will be found and the expectation value of the scale factor will be calculated. As in usual quantum cosmology, it will be shown that the quantum theory smooth out the big-bang singularity, but the classical behavior of the universe is recovered in the low-energy limit.