Perturbative Non-Equilibrium Thermal Field Theory to all Orders in Gradient Expansion

Abstract

We present a new perturbative formulation of non-equilibrium thermal field theory, based upon non-homogeneous free propagators and time-dependent vertices. The resulting time-dependent diagrammatic perturbation series are free of pinch singularities without the need for quasi-particle approximation or effective resummation of finite widths. After arriving at a physically meaningful definition of particle number densities, we derive master time evolution equations for statistical distribution functions, which are valid to all orders in perturbation theory and to all orders in a gradient expansion. For a scalar model, we perform a perturbative loopwise truncation of these evolution equations, whilst still capturing fast transient behaviour, which is found to be dominated by energy-violating processes, leading to the non-Markovian evolution of memory effects.

7 pages, 4 figures; version accepted for publication in Physics Letters B

References in corpus (7)

• Leptogenesis
• Quantum Boltzmann Equations and Leptogenesis
• Far-from-equilibrium quantum many-body dynamics
• Quantum Resonant Leptogenesis and Minimal Lepton Flavour Violation
• Perturbative Non-Equilibrium Thermal Field Theory
• On the Langevin description of nonequilibrium quantum fields
• All orders Boltzmann collision term from the multiple scattering expansion of the self-energy

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• Perturbative Non-Equilibrium Thermal Field Theory
• Open quantum dynamics induced by light scalar fields
• Lepton asymmetry from mixing and oscillations
• A new method for directly computing reduced density matrices
• Influence functionals, decoherence and conformally coupled scalars
• Density matrix formalism for interacting quantum fields
• Flavour effects in Resonant Leptogenesis from semi-classical and Kadanoff-Baym approaches
• Causality and Renormalization in Finite-Time-Path Out-of-Equilibrium ${\varphi }^3$ QFT
• Backreaction Effects on Nonequilibrium Spectral Function
• Reconciling resonant leptogenesis and baryogenesis via neutrino oscillations