Thermal field theory to all orders in gradient expansion

3rd Symposium on Prospects in the Physics of Discrete Symmetries

Millington, Peter^1 ; Pilaftsis, Apostolos^2

Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, United Kingdom^1

Consortium for Fundamental Physics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom^2

关键词: Evolution equations;    Non-markovian evolutions;    Particle number density;    Perturbation series;    Perturbation theory;    Quasi-particle approximation;    Statistical distribution function;    Time evolution equations;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/447/1/012071/pdf
DOI  :  10.1088/1742-6596/447/1/012071

来源: IOP

【 摘 要 】

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 all orders in a gradient expansion. For a scalar model, we make a loopwise truncation of these evolution equations, whilst still capturing fast transient behaviour, which is found to be dominated by energy-violating processes, leading to non-Markovian evolution of memory effects.