Low-scale leptogenesis and soft supersymmetry breaking.

Area of Science:

• Particle Physics
• Cosmology
• Supersymmetry

Background:

• The observed dominance of matter over antimatter in the universe (baryon asymmetry) is a key cosmological puzzle.
• Leptogenesis is a leading theoretical mechanism to explain this asymmetry.
• The minimal supersymmetric standard model (MSSM) offers a framework for exploring new physics beyond the Standard Model.

Purpose of the Study:

• To investigate the viability of leptogenesis at low energy scales within an extended minimal supersymmetric standard model.
• To explore the role of soft supersymmetry breaking terms in generating lepton number and CP violation.
• To assess the consistency of low-scale leptogenesis with current neutrino mass data.

Main Methods:

• Utilizing the minimal supersymmetric standard model augmented with right-handed (s)neutrinos.
• Analyzing the conditions for successful leptogenesis at approximately TeV energy scales.
• Comparing model predictions with experimental constraints from neutrino physics.

Main Results:

• Demonstrated that successful leptogenesis can be readily achieved at low energy scales (around TeV).
• Identified soft supersymmetry breaking terms as the source of necessary lepton number and CP violation.
• Confirmed the compatibility of this low-scale leptogenesis scenario with existing neutrino mass measurements.

Conclusions:

• Low-scale leptogenesis is a plausible mechanism within supersymmetric extensions of the Standard Model.
• Supersymmetry breaking provides a natural origin for the CP and lepton number violation required for leptogenesis.
• The proposed scenario offers a consistent explanation for both the matter-antimatter asymmetry and neutrino properties.