1997/09/19 by A. Niégawa
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Amplitude #Cosmology and Gravitation Theories #Gravitational singularity #Non-equilibrium thermodynamics #Perturbation theory (quantum mechanics) #Physics #Pinch #Quantum #Quantum electrodynamics #Quantum field theory #Quantum gravity #Quantum mechanics #Renormalization #Statistical physics #Theoretical and Computational Physics #Thermal quantum field theory #hep-th
paper · pdf · doi:10.1016/s0370-2693(97)01299-9
published as Phys.Lett. B416 (1998) 137-143 · 12pages
arxiv created 1997/09/19 · openalex publication_date 1998/01/01 · arxiv updated 2016/08/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Through introducing a notion of renormalization of particle-number density, a simple perturbation scheme of nonequilibrium quantum-field theory is proposed. In terms of the renormalized particle-distribution functions, which characterize the system, the structure of the scheme (and then also the structure of amplitudes and reaction rates) are the same as in the equilibrium thermal field theory. Then, as an obvious consequence, the amplitudes and reaction rates computed in this scheme are free from pinch singularities due to multiple products of δ-functions, which inevitably present in traditional perturbation scheme.