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Published on: November 15, 2013
Temperature dependence of standard model CP violation.
Tomáš Brauner1, Olli Taanila, Anders Tranberg
1Faculty of Physics, University of Bielefeld, D-33615 Bielefeld, Germany and Department of Theoretical Physics, Nuclear Physics Institute ASCR, 25068 Řež, Czech Republic.
Physical Review Letters
|March 10, 2012
Summary
CP violation effects in the standard model decrease rapidly with temperature. This suggests the cold electroweak baryogenesis scenario may be viable if the electroweak transition temperature is low.
Area of Science:
- Particle Physics
- Cosmology
- Quantum Field Theory
Background:
- CP violation is crucial for explaining the matter-antimatter asymmetry in the universe.
- The Standard Model's ability to generate this asymmetry at the electroweak phase transition is under investigation.
Purpose of the Study:
- To analyze the temperature dependence of CP violation effects within the Standard Model.
- To determine the conditions under which CP violation can occur at finite temperatures.
Main Methods:
- Integration of fermion fields to obtain the bosonic effective action.
- Application of a covariant gradient expansion to the effective action.
- Analysis of CP violating terms at different orders of the expansion.
Main Results:
- Non-vanishing CP violating terms were found starting at the sixth order of the covariant gradient expansion.
- These terms exist in the C-odd-P-even sector and depend on fundamental parameters like quark masses and Higgs field magnitude.
- CP violating effects were observed to diminish significantly with increasing temperature.
Conclusions:
- The rapid decrease of CP violation with temperature has implications for baryogenesis in the early universe.
- The Standard Model may support a cold electroweak baryogenesis scenario if the transition temperature is approximately 1 GeV.
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