2013/04/30 by Peter Millington, Apostolos Pilaftsis
Mathematics · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Classical mechanics #Cosmology and Gravitation Theories #Diagrammatic reasoning #Gravitational singularity #High-Energy Particle Collisions Research #Mathematical physics #Mathematics #Perturbation theory (quantum mechanics) #Physics #Propagator #Quantum gravity #Quantum mechanics #Resummation #Scalar field #Scalar field theory #Series expansion #Statistical physics #Thermal equilibrium #Thermal quantum field theory #Truncation (statistics) #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2013.05.044
published as Phys.Lett.B724:56-62,2013 · 7 pages, 4 figures; version accepted for publication in Physics Letters B
openalex publication_date 2013/05/21 · arxiv created 2013/06/06 · arxiv updated 2013/07/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.