Supersymmetry, Naturalness, and Light Higgsinos

Abstract

We compare and contrast three different sensitivity measures, ${\Delta }_{EW}^{-1}$, ${\Delta }_{HS}^{-1}$ and ${\Delta }_{BG}^{-1}$ that have been used in discussions of fine-tuning. We argue that though not a fine-tuning measure, ${\Delta }_{EW}$, which is essentially determined by the particle spectrum, is important because ${\Delta }_{EW}^{-1}$ quantifies the minimum fine-tuning present in any theory with a specified spectrum. We emphasize the critical role of incorporating correlations between various model parameters in discussions of fine-tuning. We provide toy examples to show that if we can find high scale theories with specific correlations amongst parameters, the value of the traditional fine-tuning measure ${\Delta }_{BG}^{-1}$ (which differs significantly from ${\Delta }_{HS}^{-1}$ only when these correlations are important) would be close to ${\Delta }_{EW}^{-1}$. We then set up the radiatively driven natural SUSY framework that we advocate for phenomenological analyses of natural models of supersymmetry, and review the implications of naturalness for LHC and ILC searches for SUSY as well as for searches for SUSY dark matter.

23 pages, 4 figures, Invited contribution to the Volume Commemorating C.V.Raman's 125th Birth Anniversary; v2: added footnote 7 and updated references, published version; v3: The cross sections for the pair production of electroweak-inos shown in Fig.2 were too high by a factor 2. The error is confined to just this figure, and does not affect any other results in the paper

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• Compressed supersymmetry and natural neutralino dark matter from top squark-mediated annihilation to top quarks
• Relaxed fine-tuning in models with non-universal gaugino masses
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Cited by in corpus (19)

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• Revisiting fine-tuning in the MSSM
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• Natural generalized mirage mediation
• Exploring MSSM for Charge and Color Breaking and Other Constraints in the Context of Higgs@125 GeV
• What is a Natural SUSY scenario?
• A natural Little Hierarchy for SUSY from radiative breaking of PQ symmetry
• The Reach of the High-Energy LHC for Gluinos and Top Squarks in SUSY Models with Light Higgsinos
• Supergravity gauge theories strike back: There is no crisis for SUSY but a new collider may be required for discovery
• The LHC higgsino discovery plane for present and future SUSY searches
• New angular (and other) cuts to improve the higgsino signal at the LHC
• Comparison of SUSY spectra generators for natural SUSY and string landscape predictions
• The cosmological moduli problem and naturalness
• Tagging a mono-top signature in Natural SUSY
• Exploring Charge and Color Breaking vacuum in Non-Holomorphic MSSM
• Radiative Corrections to Aid the Direct Detection of the Higgsino-like Neutralino Dark Matter: Spin-Independent Interactions
• Gauge Mediation Models with Adjoint Messengers
• Detecting Heavy Higgs Bosons from Natural SUSY at a 100 TeV Hadron Collider