Talks

Recent data from the PAMELA, Fermi/LAT and INTEGRAL/SPI experiments, among others, give evidence of excess electrons and positrons in the galaxy, which might be due to annihilation of dark matter. Models in which the dark matter transforms under a hidden nonabelian gauge symmetry can naturally account for the unusual features needed to fit these data. I will discuss generic features of such models, some of their distinctive consequences for cosmology, and new results for reconciling their predictions with the anomalous observations. Special attention will be given to the 511 keV gamma ray excess observed by INTEGRAL, and to the possibility that high energy lepton excesses get significant contributions from dark matter annihilation in subhalos rather than the main halo of our galaxy.

I will discuss the qualitative differences between the single-field and multifield cyclic universes, in particular the resulting global "phoenix" structure and its relation to dark energy. The multifield cyclic universe arises naturally from embedding the cyclic universe in supergravity and leads to distinct observational predictions regarding non-gaussian signatures in the CMB. I will present a simplified derivation of these predictions.