Revisiting fine-tuning in the MSSM

Abstract

We evaluate the amount of fine-tuning in constrained versions of the minimal supersymmetric standard model (MSSM), with different boundary conditions at the GUT scale. Specifically we study the fully constrained version as well as the cases of non-universal Higgs and gaugino masses. We allow for the presence of additional non-holomorphic soft-terms which we show further relax the fine-tuning. Of particular importance is the possibility of a Higgsino mass term and we discuss possible origins for such a term in UV complete models. We point out that loop corrections typically lead to a reduction in the fine-tuning by a factor of about two compared to the estimate at tree-level, which has been overlooked in many recent works. Taking these loop corrections into account, we discuss the impact of current limits from SUSY searches and dark matter on the fine-tuning. Contrary to common lore, we find that the MSSM fine-tuning can be as small as 10 while remaining consistent with all experimental constraints. If, in addition, the dark matter abundance is fully explained by the neutralino LSP, the fine-tuning can still be as low as $\sim$ 20 in the presence of additional non-holomorphic soft-terms. We also discuss future prospects of these models and find that the MSSM will remain natural even in the case of a non-discovery in the foreseeable future.

23 pages, 10 figures; v2: added references, matches published version

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Cited by in corpus (10)

• Revisiting the SUSY mu problem and its solutions in the LHC era
• Digging Deeper for New Physics in the LHC Data
• Detecting hidden sector dark matter at HL-LHC and HE-LHC via long-lived stau decays
• Exploring Non-Holomorphic Soft Terms in the Framework of Gauge Mediated Supersymmetry Breaking
• Supergravity Models with 50-100 TeV Scalars, SUSY Discovery at the LHC and Gravitino Decay Constraints
• Exploring Charge and Color Breaking vacuum in Non-Holomorphic MSSM
• Naturalness and a light $Z^{\prime }$
• A Stronger Case for Superunification Post Higgs Boson Discovery
• Supersymmetric models in view of recent LHC data
• The Multiple Point Principle and Extended Higgs Sectors