The DBI Pseudo-Conformal Universe: Scale Invariance from Spontaneous Breaking of Conformal Symmetry

          @misc{ pirsa_PIRSA:12050078,
            doi = {10.48660/12050078},
            url = {https://pirsa.org/12050078},
            author = {Miller, Godfrey},
            keywords = {},
            language = {en},
            title = {The DBI Pseudo-Conformal Universe: Scale Invariance from Spontaneous Breaking of Conformal Symmetry},
            publisher = {Perimeter Institute},
            year = {2012},
            month = {may},
            note = {PIRSA:12050078 see, \url{https://pirsa.org}}
          }
          

Abstract

The pseudo-conformal scenario is an alternative to inflation in which the early universe is approximately described by a conformal field theory in Minkowski space. Crucially, the cosmological background spontaneously breaks the flat space so(4,2) conformal algebra down to its so(4,1) de Sitter subalgebra, causing conformal-weight-0 fields to acquire a scale invariant spectrum of perturbations. This framework is very general, and its essential features are determined by the symmetry breaking pattern, irrespective of the details of the underlying microphysics. After reviewing the salient features of the model, I will describe a DBI realization of the pseudo-conformal scenario, in which scale-invariance is further protected by an additional shift symmetry acting on the weight-0 field.