Keldysh (Two-Time) Formalism

  • Tamás Sándor BiróEmail author
  • Antal Jakovác
Part of the SpringerBriefs in Physics book series (SpringerBriefs in Physics)


In previous chapters we dealt with the variance of the energy, its lower bound being established by quantum mechanical effects. We have shown that in a relativistic view this phenomenon converts into an off-mass-shell effect, and leads to a generalization of the probabilistic view of classical statistical physics to the use of a density operator and its spectral transform, the Wigner function. Yet, the Wigner function is just a particular view of the quantum field theoretical propagator.


  1. 1.
    C. Tsallis, Introduction to Nonextensive Statistical Mechanics (Springer, Berlin, 2009)Google Scholar
  2. 2.
    T.S. Biro, Is There a Temperature?. Fundamental Theories of Physics, vol. 1014 (Springer, Berlin, 2011)Google Scholar
  3. 3.
    A. Jakovac, A. Patkos, Resummation and Renormalization in Effective Theories of Particle Physics. Lecture Notes in Physics, vol. 912 (Springer, Berlin, 2016)CrossRefGoogle Scholar

Copyright information

© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.H.A.S. Wigner Research Centre for PhysicsBudapestHungary
  2. 2.Institute of PhysicsRoland Eötvös UniversityBudapestHungary

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