Dark energy, extra dimensions, and the Swampland
- PDF / 941,078 Bytes
- 14 Pages / 595.276 x 841.89 pts (A4) Page_size
- 54 Downloads / 203 Views
Springer
Received: May 5, 2020 Accepted: May 29, 2020 Published: June 15, 2020
Gabriele Montefalcone,a Paul J. Steinhardta,1 and Daniel H. Wesleyb a
Department of Physics, Princeton University, Princeton, NJ 08544, U.S.A. b PDT, 1745 Broadway, New York, NY 10019, U.S.A.
E-mail: [email protected], [email protected], [email protected] Abstract: Perhaps the greatest challenge for fundamental theories based on compactification from extra dimensions is accommodating a period of accelerated cosmological expansion. Previous studies have identified constraints imposed by the existence of dark energy for two overlapping classes of compactified theories: (1) those in which the higher dimensional picture satisfies certain metric properties selected to reproduce known low energy phenomenology; or (2) those derived from string theory assuming they satisfy the Swampland conjectures. For either class, the analyses showed that dark energy is only possible if it takes the form of quintessence. In this paper, we explore the consequences for theories that belong to both classes and show that the joint constraints are highly restrictive, leaving few options. Keywords: Cosmology of Theories beyond the SM, Classical Theories of Gravity, Models of Quantum Gravity ArXiv ePrint: 2005.01143
1
Corresponding author.
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP06(2020)091
JHEP06(2020)091
Dark energy, extra dimensions, and the Swampland
Contents 1 Introduction
1
2 Assumptions underlying metric-based constraints
2
3 Assumptions underlying the Swampland-based constraints
4 5 7 10
5 Conclusions
10
1
Introduction
The notion that the fundamental laws of physics governing the observed universe derive from the compactification of a general relativistic theory with extra dimensions has been a common element of many attempts at a unified theory, ranging from the seminal work of Kaluza [1] and Klein [2] to contemporary string theory. The general concept has many aesthetically appealing aspects, and one might imagine that there are far too many degrees of freedom and parameters to rule out the entire spectrum of possibilities empirically. But maybe not. Over the last two decades, it has become increasingly clear that a single observation — the discovery of dark energy and cosmic acceleration — poses a serious challenge. Now large classes of extra-dimensional theories can be ruled out independent of the compactification scale. One line of argument [3–6] assumes the metric of the extra-dimensional theory possesses properties (such as Ricci flatness) commonly selected to reproduce low energy particle and cosmology phenomenology. We will refer to the conditions obtained from this line of argument as the metric-based constraints. The key observation is that the accelerated expansion of the large three spatial dimensions causes the compactified extra-dimensions to vary with time, imposing constraints on the equation of state, wDE (z), where z is the redshift and wDE is the ratio
Data Loading...
