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Squeezed states and graviton-entropy production in the early universeSqueezed states are a very useful framework for the quantum treatment of tensor perturbations (i.e. gravitons production) in the early universe. In particular, the non equilibrium entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic blackbody radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. Within the formalism of squeezed thermal states it is also possible to discuss the stimulated emission of gravitons from an initial thermal bath, under the action of the cosmic gravitational background field. We find that at low energy the graviton production is enhanced, if compared with spontaneous creation from the vacuum; as a consequence, the inflation scale must be lowered, in order not to exceed the observed CMB quadrupole anisotropy. This effect is important, in particular, for models based on a symmetry-breaking transition which require, as initial condition, a state of thermal equilibrium at temperatures higher than the inflation scale and in which inflation has a minimal duration.
Document ID
19950007534
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Giovannini, Massimo (Turin Univ.)
Date Acquired
September 6, 2013
Publication Date
May 1, 1994
Publication Information
Publication: NASA. Goddard Space Flight Center, Third International Workshop on Squeezed States and Uncertainty Relations
Subject Category
Astrophysics
Accession Number
95N13947
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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