Stop coannihilation in the CMSSM and SubGUT models

Area of Science:

• Particle Physics
• Cosmology
• Supersymmetry

Background:

• The relic density of dark matter is a key cosmological puzzle.
• Supersymmetric models offer potential dark matter candidates, such as heavy stops.
• Stop coannihilation is a proposed mechanism to achieve the observed dark matter relic density.

Purpose of the Study:

• To investigate the role of stop coannihilation in determining heavy supersymmetric dark matter relic density.
• To analyze the impact of enhanced annihilation processes, including Goldstone modes and Sommerfeld enhancement, on dark matter abundance.
• To explore the constraints imposed by Higgs mass calculations on the stop coannihilation scenario.

Main Methods:

• Utilizing FeynHiggs 2.13.0 as the default Higgs mass calculator.
• Exploring the constrained minimal supersymmetric standard model (CMSSM) parameter space.
• Analyzing the effects of trilinear soft supersymmetry-breaking A-terms on stop masses and Higgs mass.

Main Results:

• Stop coannihilation, enhanced by stop-antistop annihilations and Sommerfeld effects, can yield viable dark matter relic densities.
• Large A-terms, while enhancing coannihilation, lead to significant stop mass splitting and suppress the Higgs mass.
• The stop coannihilation strip is constrained by Higgs mass limits, particularly for specific parameter choices.
• Sub-GUT models mitigate A-term effects, allowing for larger dark matter particle masses (up to TeV scale).

Conclusions:

• Stop coannihilation is a viable mechanism for producing heavy supersymmetric dark matter.
• The Higgs mass constraint, influenced by A-terms and calculation methods, plays a crucial role in defining the allowed parameter space.
• Sub-GUT models provide a pathway to reconcile large A-terms with Higgs mass requirements, enabling heavier dark matter candidates.