Hydrodynamic fluctuations from a weakly coupled scalar field

Abstract

Studies of non-equilibrium dynamics of cosmological phase transitions may involve a scalar field interacting weakly with the energy-momentum tensor of a thermal plasma. At late times, when the scalar field is approaching equilibrium, it experiences both damping and thermal fluctuations. We show that thermal fluctuations induce a shear viscosity and a gravitational wave production rate, and propose that including this tunable contribution may help in calibrating the measurement of the gravitational wave production rate in hydrodynamic simulations. Furthermore it may enrich their physical scope, permitting in particular for a study of the instability of growing bubbles.

5 pages. v2: minor clarifications, published version

References in corpus (7)

• Shape of the acoustic gravitational wave power spectrum from a first order phase transition
• Electroweak Bubble Wall Speed Limit
• The stickiness of sound: An absolute lower limit on viscosity and the breakdown of second order relativistic hydrodynamics
• Kubo Formulae for Second-Order Hydrodynamic Coefficients
• Moduli decay in the hot early Universe
• Bulk viscosity from hydrodynamic fluctuations with relativistic hydro-kinetic theory
• Hard thermal loops in the real-time formalism

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• Upper Bound on Thermal Gravitational Wave Backgrounds from Hidden Sectors
• Evolution of coupled scalar perturbations through smooth reheating. I. Dissipative regime
• Soft contributions to the thermal Higgs width across an electroweak phase transition
• Entropy production at electroweak bubble walls from scalar field fluctuations
• The importance of scalar fields as extradimensional metric components in Kaluza-Klein models