New Horizons in Cosmology: The Trace Anomaly, Cosmological Horizon Modes and Dynamical Dark Energy

          @misc{ pirsa_PIRSA:10100061,
            doi = {10.48660/10100061},
            url = {https://pirsa.org/10100061},
            author = {Mottola, Emil},
            keywords = {Cosmology},
            language = {en},
            title = {New Horizons in Cosmology: The Trace Anomaly, Cosmological Horizon Modes and Dynamical Dark Energy},
            publisher = {Perimeter Institute},
            year = {2010},
            month = {oct},
            note = {PIRSA:10100061 see, \url{https://pirsa.org}}
          }
          

Abstract

General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degrees of freedom in the extended effective field theory of gravity generated by the trace anomaly of massless quantum fields in curved space. Linearized perturbations of the Bunch-Davies state in de Sitter space show that these new scalar degrees of freedom are associated with macroscopic changes of state on the cosmological horizon scale, with potentially large stress tensors that can lead to substantial backreaction effects in cosmology. In the extended effective theory the cosmological ``constant" is a state dependent condensate whose value is scale dependent and which possesses an infrared stable conformal fixed point at zero. These considerations suggest that the observed dark energy of our universe may be a macroscopic finite size effect whose value depends not upon Planck scale physics but upon extreme infrared physics on the cosmological horizon scale.