Nonequilibrium dynamics of a thermal plasma in a gravitational field

Journal Article · Tue Dec 01 04:00:00 EST 1998 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.58.125021· OSTI ID:670274

Campos, A ^[1]; Hu, B L ^[2]

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1. Department of Physics, University of Maryland, College Park, Maryland 2074
2. Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

We introduce functional methods to study the non-equilibrium dynamics of a quantum massless scalar field at finite temperature in a gravitational field. We calculate the close time path (CTP) effective action and, using its formal equivalence with the influence functional, derive the noise and dissipation kernels of the quantum open system in terms of quantities in thermodynamical equilibrium. Using this fact, we formally prove the existence of a fluctuation-dissipation relation (FDR) at all temperatures between the quantum fluctuations of the plasma in thermal equilibrium and the energy dissipated by the external gravitational field. What is new is the identification of a stochastic source (noise) term arising from the quantum and thermal fluctuations in the plasma field, and the derivation of a Langevin-type equation which describes the non-equilibrium dynamics of the gravitational field influenced by the plasma. The back reaction of the plasma on the gravitational field is embodied in the FDR. From the CTP effective action the contribution of the quantum scalar field to the thermal graviton polarization tensor can also be derived and it is shown to agree with other techniques, most notably, linear response theory (LRT). We show the connection between the LRT, which is applicable for near-equilibrium conditions and the functional methods used in this work which are useful for fully nonequilibrium conditions. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 670274
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 12 Vol. 58; ISSN 0556-2821; ISSN PRVDAQ
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ACTION INTEGRAL
FLUCTUATIONS
GRAVITATIONAL FIELDS
GRAVITONS
LANGEVIN EQUATION
PLASMA
QUANTUM FIELD THEORY
QUANTUM GRAVITY
SCALAR FIELDS
STOCHASTIC PROCESSES
TENSORS