Naturalness in low-scale SUSY models and "non-linear" MSSM

Area of Science:

• High Energy Physics
• Theoretical Physics
• Particle Physics

Background:

• Minimal Supersymmetric Standard Model (MSSM) often exhibits significant electroweak fine-tuning.
• This fine-tuning is particularly pronounced for certain boundary conditions and Higgs masses (126 GeV).
• Existing fine-tuning values are often considered unacceptably large, potentially indicating issues with supersymmetry (SUSY) breaking mechanisms.

Purpose of the Study:

• To investigate a minimal modification of MSSM to restore naturalness.
• To reduce electroweak fine-tuning by altering the SUSY breaking scale.
• To explore a model without introducing additional visible sector fields.

Main Methods:

• Lowering the SUSY breaking scale in the hidden sector to a few TeV.
• Introducing effective quartic Higgs couplings proportional to the ratio of visible to hidden sector SUSY breaking scales.
• Analyzing the model in the limit where the sgoldstino component is integrated out, realizing the superfield non-linearly.

Main Results:

• Reduced electroweak fine-tuning to acceptable levels ([Formula: see text]).
• Naturalness is restored for conservative cases with low hidden sector scales and specific boundary conditions.
• The model smoothly transitions to standard gravity-mediated MSSM-like models as the hidden sector scale increases.

Conclusions:

• A minimal modification involving lowering the hidden sector SUSY breaking scale effectively addresses electroweak fine-tuning in MSSM.
• This approach provides a natural solution without requiring additional particles in the visible sector.
• The proposed model offers a continuous range of fine-tuning values, connecting to established MSSM scenarios.