Fate of oscillating scalar fields in a thermal bath and their cosmological implications

Journal Article · Mon Nov 15 04:00:00 EST 2004 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.70.103511· OSTI ID:20697982

Yokoyama, Jun'ichi ^[1]

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1. Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka 560-0043 (Japan)

Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and in an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.

• OSTI ID: 20697982
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 10 Vol. 70; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AXIOMATIC FIELD THEORY
COSMOLOGY
DISTRIBUTION FUNCTIONS
EQUATIONS OF MOTION
FERMIONS
FLUCTUATIONS
INFLATIONARY UNIVERSE
MESONS
PARTICLE INTERACTIONS
SCALAR FIELDS
TEMPERATURE DEPENDENCE
THERMAL EQUILIBRIUM
THREE-BODY PROBLEM
YUKAWA POTENTIAL