The Fate of SUSY Flat Directions and their Role in Reheating

We consider the role of supersymmetric flat directions in reheating the Universe after inflation. One or more flat directions can develop large vevs during inflation, which can potentially affect reheating by slowing down scattering processes among inflaton decay products or by coming to dominate the energy density of the Universe. Both effects occur only if flat directions are sufficiently long-lived. The computation of their perturbative decay rate, and a simple estimate of their nonperturbative decay have led to the conclusion that this is indeed the case. In contrast, we show that flat directions can decay quickly through nonperturbative channels in realistic models. The mass matrix for MSSM excitations around flat directions has nondiagonal entries, which vary with the phase of the (complex) flat directions. The quasi-periodic motion of the flat directions results in a strong parametric resonance, leading to the rapid depletion of the flat direction within its first few rotations. This may preclude any significant role for the flat directions in reheating the Universe after inflation in models in which the inflaton decays perturbatively.Comment: 30 pages, 6 .ps figures. Final published versio

Dark Energy and Dark Matter

A brief overview of our current understanding of abundance and properties of dark energy and dark matter is presented. A more focused discussion of supersymmetric dark matter follows. Included is a frequentist approach to the supersymmetric parameter space and consequences for the direct detection of dark matter.Comment: 12 pages, 8 figures, Summary of talk given at the XXIV International Symposium on Lepton Photon Interactions at High Energies, Hamburg Germany, August 200

The violent Universe: the Big Bang

Four lectures on Big Bang cosmology, including microwave background radiation, Big Bang nucleosynthesis, dark matter, inflation, and baryogenesis.Comment: 47 pages, 19 figures, Set of four lectures given at the 2009 European School of High-Energy Physics, Bautzen, Germany, June 200