Short distance and initial state effects in inflation: Stress tensor and decoherence

Journal Article · Mon Aug 15 00:00:00 EDT 2005 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.72.043515· OSTI ID:20711315

Anderson, Paul R; Molina-Paris, Carmen; Mottola, Emil ^[1]

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1. Department of Physics, Wake Forest University, Winston-Salem, North Carolina, 27109 (United States)

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 Schroedinger 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 {alpha} 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.

• OSTI ID: 20711315
• Journal Information: Physical Review. D, Particles Fields, Vol. 72, Issue 4; Other Information: DOI: 10.1103/PhysRevD.72.043515; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COSMIC RADIATION
COSMOLOGY
DE SITTER GROUP
DENSITY MATRIX
DISTANCE
EXPECTATION VALUE
GRAVITATION
HAMILTONIANS
INFLATIONARY UNIVERSE
MIXED STATE
QUANTUM FIELD THEORY
RADIOWAVE RADIATION
RELICT RADIATION
RENORMALIZATION
SCALAR FIELDS
SCHROEDINGER PICTURE
SPACE-TIME
STRESSES
TENSORS
UNIVERSE