Baryon asymmetry of the Universe without Boltzmann or Kadanoff-Baym equations

Journal Article · Tue Mar 15 04:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.065021· OSTI ID:21537583

Gagnon, Jean-Sebastien; Shaposhnikov, Mikhail ^[1]

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1. Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland) and Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)

We present a formalism that allows the computation of the baryon asymmetry of the Universe, from the first principles of statistical physics and quantum field theory, that is applicable to certain types of physics beyond the standard model (such as the neutrino minimal standard model) 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 neutrino minimal standard model 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 nonequilibrium 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.

• OSTI ID: 21537583
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 83; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
BARYONS
CALCULATION METHODS
COMPUTERIZED SIMULATION
CORRELATION FUNCTIONS
CP INVARIANCE
ELEMENTARY PARTICLES
EQUATIONS
EQUILIBRIUM
EXPANSION
FERMIONS
FIELD THEORIES
FUNCTIONS
GRAND UNIFIED THEORY
HADRONS
INVARIANCE PRINCIPLES
KINETIC EQUATIONS
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATHEMATICAL SOLUTIONS
NEUTRINOS
PARTICLE MODELS
QUANTUM FIELD THEORY
SIMULATION
STANDARD MODEL
UNIFIED GAUGE MODELS