Scalar fields appear in many cosmological models, particular order to provide explanations for dark energy and inflation, but also emulate matter. In this paper, we show that it is possible a scalar field replace simultaneously matter, inflation by assuming the existence of non-minimal coupling gravity, Mexican hat potential, spontaneous symmetry breaking before inflation. After behaves like fl...

We study the impact of bound state formation on dark matter annihilation rates in models where dark matter interacts via a light mediator, the dark photon. We derive the general cross section for radiative capture into all possible bound states, and point out its nontrivial dependence on the dark matter velocity and the dark photon mass. For indirect detection, our result shows that dark matter...

MACHe3 (MAtrix of Cells of superfluid He) is a project of a new detector for direct Dark Matter Search. The idea is to use superfluid He as a sensitive medium. The existing device, the superfluid He cell, will be briefly introduced. Then a description of the MACHe3 project will be presented, in particular the background rejection and the neutralino event rate that may be achieved with such a de...

In the last decade considerable additional evidence has been gathered supporting the hypothesis that at least 90% of the mass in the universe is dark: it does not emit or absorb any form of electromagnetic radiation. Understanding this dark matter has become one of the more central problems in astronomy and cosmology. Once a subject of controversy among astronomers, its existence is now well es...

We present a model with a complex and a real scalar fields and a potential whose symmetry is explicitly broken by Planck-scale physics. For exponentially small breaking, the model accounts for the period of inflation in the early universe and for the period of acceleration of the late universe or for the dark matter, depending on the smallness of the explicit breaking.

The axino is the fermionic superpartner of the axion. Assuming the axino is the lightest supersymmetric particle and stable due to R-parity conservation, we compute the relic axino density from thermal reactions in the early Universe. From the comparison with the WMAP results, we find that thermally produced axinos could provide the dominant part of cold dark matter, for example, for an axino m...

(thank you Brian, Roni, Paddy for putting together a wonderful workshop ! Workshop addressed issues of light dark matter and " dark forces " –possible new interactions of dark sector)

Cosmological observations are normally fit under the assumption that the dark sector can be decomposed into dark matter and dark energy components. However, as long as the probes remain purely gravitational, there is no unique decomposition and observations can only constrain a single dark fluid; this is known as the dark degeneracy. We use observations to directly constrain this dark fluid in ...