MG12 - Talk detail
 

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Talk

Abstract

Dark Matter via Many Copies of the Standard Model

We propose a cosmological scenario based on the assumption that the Standard Model possesses a large number of copies. It is demonstrated that baryons in the hidden copies of the standard model can naturally account for the dark matter. The right abundance of the hidden-sector baryons and the correct spectrum of density perturbations are simultaneously generated during modulated reheating. We show that for the natural values of inflaton coupling constants, dictated by unitarity, the dark-matter abundance is predicted to be proportional to the ratio of observed cosmological parameters: the square of the amplitude of cosmological perturbations and the baryon-to-photon number ratio.

Structure Formation in f(R) Gravity Consistent with Solar-System Tests

I will discuss cosmological predictions for a class f(R) models of modified gravity which is able to evade Solar-System tests in a part of its parameter space. Interestingly, the constraints arise as a result of the requirement that the galactic halo be in a `high-curvature' regime. If this requirement is satisfied, solar-system test alone place no further constraints. I will show that large-scale structure forms differently in such modified cosmologies which results an increased amplitude for the matter power spectrum and introduces scale dependence in the amplitude, which should be detectable in the near future.

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