Talks

We  will  briefly review  the  issue  of    "information loss"    during  the Hawking   evaporation of a  black hole,  and  argue that    the  quantum dynamical  reduction  theories, which  have  been  developed to  address the   measurement problem  in quantum mechanics,  possess the  elements to  diffuse the ``paradox”  at the qualitative  and  at   the  quantitative  level, leading to what  seems  to be an overall  coherent  picture.  

The  QCD axion is a curious Dark Matter candidate, having a mass like the neutrino, but behaving as Cold Dark Matter. I will review how this occurs, and discuss the interesting question  of whether WIMPs could be distinguished from axions with Large Scale Structure data.

The properties of a strange metal fermion model with infinite-range

interactions turn out to be closely related to those of charged black holes

with AdS2 horizons. I show that a microscopic computation of the ground

state entropy density of the fermion model yields precisely the Bekenstein-Hawking

entropy density of the black hole. The fermion model is UV finite and has no supersymmetry

Although the inflationary predictions for the primordial power spectrum of    density inhomogeneities   seem  very successful, there is an obscure part in our understanding of the emergence of the seeds of cosmic   structure:  How  does  a universe which at one pint  in time is described by a  state that is fully  homogeneous and isotropic,  evolve into a state that is not,   given that the dynamics  does not  contain any  source  for the  undoing of  such symmetry?   We will  discuss  an   approach that  offers  a resolution  of the  issue  in the context of  proposals to deal  with the measurement  problem in quantum  mechanics. We will  see that the   approach  naturally  resolves the difficulties  raised  by the  lack of  observation of tensor modes.

Path integrals are at the heart of quantum field theory. In spite of their covariance and seeming simplicity, they are hard to define and evaluate. In contrast, functional differentiation, as it is used, for example, in variational problems, is relatively straightforward. This has motivated the development of new techniques that allow one to express functional integration in terms of functional differentiation. In fact, the new techniques allow one to express integrals in general through differentiation. These techniques therefore add to the general toolbox for integration and integral transforms such as the Fourier and Laplace transforms. Here, we review some of these results, we give simpler proofs and we add new results, for example, on expressing the Laplace transform and its inverse in terms of derivatives, results that may be of use in quantum field theory, e.g., in the context of heat traces.