2005/04/30 by Paul R. Anderson, Carmen Molina-Paris, Carmen Molina-Parı́s +1
Physics and Astronomy · #Adiabatic process #Adiabatic quantum computation #Black Holes and Theoretical Physics #Classical mechanics #Cosmic microwave background #Cosmology and Gravitation Theories #De Sitter universe #Hamiltonian (control theory) #Mathematical physics #Non-Gaussianity #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum computer #Quantum decoherence #Quantum mechanics #Scalar field #Universe #Vacuum state #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.72.043515
published as Phys.Rev. D72 (2005) 043515 · 83 pages, 2 figures, minor changes in content and style
arxiv created 2005/06/13 · openalex publication_date 2005/08/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a consistent low energy effective field theory framework for parametrizing the effects of novel short distance physics in inflation, and their possible observational signatures in the cosmic microwave background. We consider the class of general homogeneous, isotropic initial states for quantum scalar fields in Robertson-Walker (RW) spacetimes, subject to the requirement that their ultraviolet behavior be consistent with renormalizability of the covariantly conserved stress tensor which couples to gravity. In the functional Schr"odinger picture such states are coherent, squeezed, mixed states characterized by a Gaussian density matrix. This Gaussian has parameters which approach those of the adiabatic vacuum at large wave number, and evolve in time according to an effective classical Hamiltonian. The one complex parameter family of \ensuremathα squeezed states in de Sitter spacetime does not fall into this UV allowed class, except for the special value of the parameter corresponding to the Bunch-Davies state. We determine the finite contributions to the inflationary power spectrum and stress tensor expectation value of general UV allowed adiabatic states, and obtain quantitative limits on the observability and backreaction effects of some recently proposed models of short distance modifications of the initial state of inflation. For all UV allowed states, the second order adiabatic basis provides a good description of particles created in the expanding RW universe. Because of the absence of particle creation for the massless, minimally coupled scalar field in de Sitter space, there is no phase decoherence in the simplest free field inflationary models. We apply adiabatic regularization to the renormalization of the decoherence functional in cosmology to corroborate this result.