Uniting Low-Scale Leptogenesis Mechanisms.

Area of Science:

• Particle Physics
• Cosmology
• Neutrino Physics

Background:

• The origin of baryon asymmetry, the imbalance between matter and antimatter in the universe, is a fundamental question in physics.
• Existing models for baryogenesis, such as leptogenesis, often involve right-handed Majorana neutrinos with masses near the Grand Unified Theory scale.

Purpose of the Study:

• To demonstrate the unification of two distinct mechanisms of baryon asymmetry generation: leptogenesis via neutrino oscillations and resonant leptogenesis.
• To show that these mechanisms are effective for a broad range of experimentally allowed right-handed neutrino masses.

Main Methods:

• Theoretical analysis of baryon asymmetry generation involving two right-handed Majorana neutrinos with masses significantly below the Grand Unified Theory scale.
• Investigating the parameter space including neutrino mass splitting and mixing angles.

Main Results:

• The previously distinct mechanisms of leptogenesis via neutrino oscillations and resonant leptogenesis are shown to be unified.
• The observed baryon asymmetry can be generated for all experimentally allowed right-handed neutrino masses above approximately 100 MeV.
• Leptogenesis is effective across a wide parameter range, including significant mass splitting and large mixing angles.

Conclusions:

• The unified leptogenesis model provides a consistent explanation for the observed baryon asymmetry.
• The model's predictions for neutrino masses and mixing angles are testable with current and future high-intensity experiments and colliders.