Ho\v{r}ava-Lifshitz $F(\bar{R})$ theories and the Swampland

TL;DR

This paper investigates the compatibility of Hořava-Lifshitz $F(ar{R})$ gravity theories with the de Sitter Swampland conjecture, deriving parameter restrictions and analyzing different formulations to understand their theoretical viability.

Contribution

It introduces a detailed analysis of $F(ar{R})$ theories within Hořava-Lifshitz gravity, establishing parameter constraints for compatibility with the Swampland conjecture and exploring various model limits.

Findings

$ ext{dS}$ conjecture restricts $oxed{ ext{parameters } \lambda ext{ near } 1/3}$

The form of $F(ar{R})$ includes $ar{R}^ ext{power}$ terms with negative powers possible

Parameter relations $oxed{ ext{restrict } \lambda o 1/3 ext{ as } \mu o 0}$

Abstract

The compatibility between the de Sitter Swampland conjecture and Ho\v{r}ava--Lifshitz $F(\bar{R})$ theories with a flat FLRW metric is studied. We first study the standard $f(R)$ theories and show that the only way in which the dS conjecture can be made independent of $R$ is by considering a power law of the form $f(R)\sim R^{\gamma}$. The conjecture and the consistency of the theory puts restrictions on $\gamma$ to be greater but close to one. For $F(\bar{R})$ theories described by its two parameters $\lambda$ and $\mu$, we use the equations of motion to construct the function starting with an ansatz for the scale factor in the Jordan frame of the power law form. By performing a conformal transformation on the three metric to the Einstein frame, we can obtain an action of gravity plus a scalar field by relating the parameters of the theory. The non-projectable and projectable cases are studied and the differences are outlined. The obtained $F(\bar{R})$ function consists of terms of the form $\bar{R}^{\gamma}$ with the possibility of having negative power terms. The dS conjecture leads to inequalities for the $\lambda$ parameter; in both versions, it becomes restricted to be greater but close to $1/3$. We can also study the general case in which $\mu$ and $\lambda$ are considered as independent. The obtained $F$ function has the same form as before. The consistency of the theory and the dS conjecture lead to a set of inequalities on both parameters that are studied numerically. In all cases, $\lambda$ is restricted by $\mu$ around $1/3$, and we obtain $\lambda\to1/3$ if $\mu\to0$. We consider the $f(R)$ limit $\mu,\lambda \to 1$ and we obtain consistent results. Finally, we study the case of a constant Hubble parameter. The dS conjecture can be fulfilled by restricting the parameters of the theory; however, the constraint makes this compatibility exclusive to these kinds of theories.