Search Talks

We review the notion of a quantum state of the universe and its role in fundamental cosmology. Then we discuss recent work which points towards a profound connection, at the level of the quantum state, between (asymptotic) Euclidean AdS spaces and Lorentzian de Sitter spaces. This gives a new framework in which (a mild generalization of) AdS/CFT can be applied to inflationary cosmology.   For the specific case of the Hartle-Hawking no-boundary quantum state the ADS/ de Sitter connection yields a natural proposal for a more precise `dual' formulation of the wave function, in terms of field theories on the future de Sitter boundary that are certain relevant deformations of the CFTs that occur in AdS/CFT.

The curvaton scenario provides a simple explanation for the generation of the cosmological perturbations, however most works have focused on cases with rather trivial curvaton energy potentials, e.g. quadratic ones. In this talk I will present the rich phenomenology of curvatons by showing that non-quadratic curvatons exhibit new behaviors, leading to interesting signals in the resulting density perturbations. A string theory realization of the curvaton scenario will also be discussed, where D-branes located in a warped throat region of the internal space play the role of curvatons.

In this talk I will present evidence that accounting for the presence of hierarchies in string compactifications naturally leads to a UV sensitivity of dark matter in contrast to what is usually assumed. In particular, we will see that the existence of cosmological moduli may lead to a non-thermal history for the early universe and modifications in the primordial production of dark matter. If such a history were realized it would not only require probing new regions in dark matter searches, but also imply that a detection of dark matter would provide a direct probe on the early universe and the UV -- contrary to the thermal WIMP case. Regardless of the history of the early universe I will argue that if current string constructions are representative of more general models then all weak-scale dark matter would indeed be UV sensitive and would be a new prediction of string theory - falsifiable by experiment.

Dwarf galaxies are the most know dark matter dominated luminous objects in Universe. Observing the line of sight velocity and position of stars in Milky way satellites, and assuming the dark matter potential and a specific configuration of stellar orbits, one can obtain the mass profile of dark matter in galaxies. In this talk I will show that by considering a generic case of  phase-space density as a function of energy and angular momentum and by relaxing the specific choice of orbital configuration (which is assumed in literature), we can find  the dark matter potential and mass profile in this general case and restudy the challenges of Cold Dark Matter(CDM) paradigm like core-cusp or missing satellite problem.