Hořava-Lifshitz $F(\bar{R})$ theories and the Swampland

Abstract

The compatibility between the de Sitter Swampland conjecture and Hořava--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 $\lambda \to 1/3$ if $\mu \to 0$. 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.

34 pages, 6 figures. All sections were improved. Subsection 4.5 added. References added

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Cited by in corpus (1)

• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme