Baryon Asymmetry of the Universe without Boltzmann or Kadanoff-Baym

Abstract

We present a formalism that allows the computation of the baryon asymmetry of the universe from first principles of statistical physics and quantum field theory that is applicable to certain types of beyond the Standard Model physics (such as the neutrino Minimal Standard Model -- $\nu$MSM) and does not require the solution of Boltzmann or Kadanoff-Baym equations. The formalism works if a thermal bath of Standard Model particles is very weakly coupled to a new sector (sterile neutrinos in the $\nu$MSM case) that is out-of-equilibrium. The key point that allows a computation without kinetic equations is that the number of sterile neutrinos produced during the relevant cosmological period remains small. In such a case, it is possible to expand the formal solution of the von Neumann equation perturbatively and obtain a master formula for the lepton asymmetry expressed in terms of non-equilibrium Wightman functions. The master formula neatly separates CP-violating contributions from finite temperature correlation functions and satisfies all three Sakharov conditions. These correlation functions can then be evaluated perturbatively; the validity of the perturbative expansion depends on the parameters of the model considered. Here we choose a toy model (containing only two active and two sterile neutrinos) to illustrate the use of the formalism, but it could be applied to other models.

26 pages, 10 figures

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Cited by in corpus (20)

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• Sterile Neutrino Dark Matter
• The Phenomenology of Right Handed Neutrinos
• Dark Matter, Baryogenesis and Neutrino Oscillations from Right Handed Neutrinos
• Leptogenesis from first principles in the resonant regime
• Effective Theory of Resonant Leptogenesis in the Closed-Time-Path Approach
• Thermal right-handed neutrino production rate in the non-relativistic regime
• Kadanoff-Baym Approach to Flavour Mixing and Oscillations in Resonant Leptogenesis
• Consequences of DM/antiDM Oscillations for Asymmetric WIMP Dark Matter
• Thermal right-handed neutrino production rate in the relativistic regime
• Systematic approach to thermal leptogenesis
• Kubo relations and radiative corrections for lepton number washout
• Perturbative Non-Equilibrium Thermal Field Theory
• Kadanoff-Baym approach to the thermal resonant leptogenesis
• Lepton asymmetry from mixing and oscillations
• On the Role of Quasiparticles and thermal Masses in Nonequilibrium Processes in a Plasma
• Beyond the MSW effect: Neutrinos in a dense medium
• Kinetic equations for sterile neutrinos from thermal fluctuations
• Perturbative Non-Equilibrium Thermal Field Theory to all Orders in Gradient Expansion
• Flavour effects in Resonant Leptogenesis from semi-classical and Kadanoff-Baym approaches