The dynamics of scalar fields in the early universe

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:6741945

Feldman, H A

The dynamical evolution of weakly coupled scalar fields in the early universe is discussed. Such fields would be out of thermal equilibrium, and their initial distribution highly inhomogeneous. The classical evolution was studied in the pre-inflationary, radiation dominated universe, and under which conditions the fields dynamically relax to configurations which give inflation was discussed. The effects of thermal fluctuations in a model of new inflation with a double-well potential are studied. The stochastic approach to inflation is extended to cover a situation in which spatial gradient terms and acceleration terms in the equation of motion of the scalar field dominate. These effects are explored numerically to complement the analytical investigation. A critical value of the strength of the coupling to the thermal bath is found, above which thermal fluctuations do not allow the inflationary period to begin. The evolution of the scalar field is followed until the onset of the inflationary period. Gravitational perturbations about the Friedmann-Robertson-Walker metric are taken into account. Making use of gauge invariant variables, it is shown, both analytical and numerically, that provided the initial gravitational perturbations are not too large, they do not prevent the dynamical relaxation of the scalar field configuration to an almost homogeneous configuration which leads inflation. A detailed derivation of the Einstein equations and the equation of motion for the scalar fields and their perturbations including the effects of back reaction in the analysis, is given. Different gauge choices are explored and discussed. Numerical simulation of the dynamical evolution of both the scalar field and the metric perturbation variable is done.

• Research Organization: State Univ. of New York, Stony Brook, NY (USA)
• OSTI ID: 6741945
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMOLOGICAL MODELS
SCALAR FIELDS
UNIVERSE
EINSTEIN FIELD EQUATIONS
EQUATIONS OF MOTION
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
PERTURBATION THEORY
STOCHASTIC PROCESSES
THEORETICAL DATA
VARIATIONS
DATA
DIFFERENTIAL EQUATIONS
EQUATIONS
FIELD EQUATIONS
INFORMATION
NUMERICAL DATA
PARTIAL DIFFERENTIAL EQUATIONS
640106* - Astrophysics & Cosmology- Cosmology