Related papers: Dark Matter in Models of String Cosmology
It is well known that light scalar fields present during inflation are coherently excited. We show that if the field couples to gravity in a non-minimal way, the fluctuations at large scales are suppressed with respect to the small scales…
The concept of exotic charged dust is introduced here to represent dark matter. The term "exotic" means that the dust is not composed of normal matter, and the charge--for lack of a better term--is not an electric charge. It is also shown…
About 80 percent of the matter content of the universe is dark matter. However, the particle origin of dark matter is yet to be established. Many extensions of the Standard Model (SM) contain candidates of dark matter. The search for the…
The axion has emerged in recent years as a leading particle candidate to provide the mysterious dark matter in the cosmos, as we review here for a general scientific audience. We describe first the historical roots of the axion in the…
We investigate if the fluctuations of the scalar field mediating quintessence -- the cosmon -- can play an important role in cosmology. Small fluctuations with short wavelength behave similar to a relativistic gas. In contrast, the…
The origin of dark matter as a thermal relic offers a compelling way in which the early universe was initially populated by dark matter. Alternative explanations typically appear exotic compared to the simplicity of thermal production.…
Motivated by inflation, the theory of big-bang nucleosynthesis and the quest for a deeper understanding of the fundamental forces and particles, a very successful paradigm for the development of structure in the Universe has evolved. It…
Light scalar and pseudoscalar particles are compelling dark matter candidates, with a vast running experimental program to discover them. Previous studies have shown that these light fields can generate sizable isocurvature perturbations in…
Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the…
It is obtained that dark energy emerges from higher-derivative gravity with anon-linear terms proportional to $R^2$ and $R^3$ with $R$ being the Ricci scalar curvature. Interestingly, it is found that the universe begins with acceleration,…
We generalize dark matter production to a two-metric framework whereby the physical metric, which couples to the Standard Model (SM), is conformally and/or disformally related to the metric governing the gravitational dynamics. We show that…
We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to…
Cosmic strings can be created in the early universe during symmetry-breaking phase transitions, such as might arise if the gauge structure of the standard model is extended by additional U(1) factors at high energies. Cosmic strings present…
The idea that dark matter could be made of stable relics of microscopic black holes is not new. In this article, we revisit this hypothesis, focusing on the creation of black holes by the scattering of trans-Planckian particles in the early…
The particle that makes up the dark matter of the universe could be an axion or axion-like particle. A collection of axions can condense into a bound Bose-Einstein condensate called an axion star. It is possible that a significant fraction…
Dark energy is the candidate that can produce effective negative pressure and make the galaxies and galaxy clusters move away from each other in an accelerated way. The structures of the Universe have evolved from some initial primordial…
Motivated by their potential role as dark matter, we study the cosmological evolution of light scalar and vector fields non-minimally coupled to gravity. Our focus is on a situation where the dominant contribution to the energy density…
Primordial inflation and Dark Matter (DM) could both belong to the hidden sector. It is therefore plausible that the inflaton, which drives inflation, could couple to the DM either directly or indirectly, thus providing a common origin for…
Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing…
The axion arises in well-motivated extensions of the Standard Model of particle physics and is regarded as an alternative to the weakly interacting massive particle paradigm to explain the nature of dark matter. In this contribution, we…