Quantum effects of interacting fields in the early Universe
The effective-action formalism used by Hartle, Hu, Fischetti, and Anderson for treating particle production and back reaction of free fields near the Planck time in the early Universe is extended here to interacting fields. We consider a massive (m) self-interacting lambdaphi/sup 4/ scalar field coupled (xi) to a Friedmann-Robertson-Walker spacetime and study the effect of interaction on particle production and on the dynamics of the background geometry. A background-field splitting is introduced in the one-loop effective action which is calculated by perturbative expansions up to the second order in lambda, m/sup 2/, and xi. Ultraviolet divergences from the fluctuation field are removed by introducing counterterms via dimensional regularization. From the regularized effective action equations governing the effective geometry and the background field are derived and their solutions sought. We consider separately the conformal versus the nonconformal (xi), and the massless versus the massive (m) cases. We also contrast the cases with or without the background field (chi) and those with or without interaction (lambda). The dynamics of the scalar field and the scale factor and the probability of pair production in each case are calculated. In the discussion we present a qualitative explanation of these results, and draw the connection with related work. The classical limit of the present problem depicts the evolution of a Higgs field in curved space, its results being useful for the description of inflation and reheating processes in the grand-unified-theory epoch. The present problem is also the semiclassical limit of quantum cosmology. The results obtained here can be useful to tackling problems involving dynamical fields in curved space such as critical dynamics in the early Universe.
- Research Organization:
- The Institute for Advanced Study, Princeton, New Jersey 08540
- OSTI ID:
- 5378528
- Journal Information:
- Phys. Rev. D; (United States), Vol. 37:8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
UNIVERSE
PARTICLE PRODUCTION
QUANTUM FIELD THEORY
COSMOLOGY
EINSTEIN FIELD EQUATIONS
GRAND UNIFIED THEORY
GRAVITATIONAL FIELDS
HIGGS MODEL
PERTURBATION THEORY
SCALAR FIELDS
SPACE-TIME
ULTRAVIOLET DIVERGENCES
EQUATIONS
FIELD EQUATIONS
FIELD THEORIES
MATHEMATICAL MODELS
PARTICLE MODELS
UNIFIED GAUGE MODELS
UNIFIED-FIELD THEORIES
640106* - Astrophysics & Cosmology- Cosmology
645400 - High Energy Physics- Field Theory