Nonsingular cosmological models: the massive scalar field case |
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Authors: | B S Sathyaprakash K P Sinha |
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Institution: | (1) Department of Physics and Mathematical Sciences, Indian Institute of Science, 560012 Bangalore, India;(2) Division of Physics and Mathematical Sciences, Indian Institute of Science, 560012 Bangalore, India |
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Abstract: | The nonminimal coupling of a massive self-interacting scalar field with a gravitational field is studied. Spontaneous symmetry
breaking occurs in the open universe even when the sign on the mass term is positive. In contrast to grand unified theories,
symmetry breakdown is more important for the early universe and it is restored only in the limit of an infinite expansion.
Symmetry breakdown is shown to occur in flat and closed universes when the mass term carries a wrong sign. The model has a
naturally defined effective gravitational coupling coefficient which is rendered time-dependent due to the novel symmetry
breakdown. It changes sign below a critical value of the cosmic scale factor indicating the onset of a repulsive field. The
presence of the mass term severely alters the behaviour of ordinary matter and radiation in the early universe. The total
energy density becomes negative in a certain domain. These features make possible a nonsingular cosmological model for an
open universe. The model is also free from the horizon and the flatness problems. |
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Keywords: | Symmetry breaking cosmology nonsingular cosmological models |
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