Relaxation and kinetics in scalar field theories

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.54.4013· OSTI ID:383430

Boyanovsky, D ^[1]; Lawrie, I D ^[2]; Lee, D ^[3]

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1. Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)
2. Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)
3. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)

A new approach to the dynamics of relaxation and kinetics of thermalization in a scalar field theory is presented that incorporates the relevant time scales through the resummation of hard thermal loops. An alternative derivation of the kinetic equations for the {open_quote}{open_quote}quasiparticle{close_quote}{close_quote} distribution functions is obtained that allows a clear understanding of the different {open_quote}{open_quote}coarse-graining{close_quote}{close_quote} approximations usually involved in a kinetic description. This method leads to a systematic perturbative expansion to obtain the kinetic equations including hard thermal loop resummation and to an improvement including renormalization, off-shell effects, and contributions that change chemical equilibrium on short time scales. As a by-product of these methods we establish the equivalence between the relaxation time scale in the linearized equation of motion of the quasiparticles and the thermalization time scale of the quasiparticle distribution function in the {open_quote}{open_quote}relaxation time approximation{close_quote}{close_quote} including hard thermal loop effects. Hard thermal loop resummation dramatically modifies the scattering rate for long wavelength modes as compared to the usual (semi)classical estimate. Relaxation and kinetics are studied both in the unbroken and broken symmetry phases of the theory. The broken symmetry phase also provides the setting to obtain the contribution to the kinetic equations from processes that involve decay of a heavy scalar into light scalar particles in the medium. {copyright} {ital 1996 The American Physical Society.}

• Research Organization: University of North Carolina
• DOE Contract Number: FG05-85ER40219
• OSTI ID: 383430
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 6 Vol. 54; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DISTRIBUTION FUNCTIONS
EQUATIONS OF MOTION
KINETIC EQUATIONS
KINETICS
QUASI PARTICLES
RELAXATION
RELAXATION TIME
SCALAR FIELDS
SYMMETRY BREAKING
THERMALIZATION
WAVELENGTHS