2013/09/30 by Howard Baer, V. Barger, Vernon Barger +1 · 6 citations
Mathematics · Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Electroweak interaction #Electroweak scale #Higgs boson #Mathematics #Minimal Supersymmetric Standard Model #Neutrino Physics Research #Parameter space #Particle physics #Particle physics theoretical and experimental studies #Physics #Statistics #Supersymmetry #hep-ph
paper · pdf · doi:10.1103/physrevd.88.095013
published as Phys. Rev. D 88, 095013 (2013) · 28 pages with 17 .png figures; version 2 has expanded references and several typos fixed; version 3 includes added discussion to coincide with published version in PRD
arxiv created 2013/10/23 · openalex publication_date 2013/11/18 · arxiv updated 2013/11/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The lack of evidence for superparticles at the CERN LHC, along with the rather high value of the Higgs boson mass, has sharpened the perception that what remains of supersymmetric model parameter space suffers a high degree of electroweak fine-tuning (EWFT). We compare three different measures of fine-tuning in supersymmetric models. First, \ensuremathΔHS measures a subset of terms containing large log contributions to mZ (and mh) that are inevitable in models defined at scales much higher than the electroweak scale. Second, the traditional \ensuremathΔBG measures fractional variation in mZ against fractional variation of model parameters and allows for correlations among high scale parameters which are not included in \ensuremathΔHS. Third, the model-independent \ensuremathΔEW measures how naturally a model can generate the measured value of mZ=91.2 GeV (or mh) in terms of weak scale parameters alone. We hypothesize an overarching ultimate theory (UTH) wherein the high scale soft terms are all correlated. The UTH might be contained within the more general effective supersymmetry theories which are popular in the literature. In the case of \ensuremathΔHS, EWFT can be grossly overestimated by neglecting additional nonindependent terms which lead to large cancellations. In the case of \ensuremathΔBG, EWFT can be overestimated by applying the measure to the effective theories instead of to the UTH. The measure \ensuremathΔEW allows for the possibility of parameter correlations which should be present in the UTH and, since it is model independent, provides the same value of EWFT for the effective theories as should occur for the UTH. We find that the well-known minimal supergravity model/constrained minimal supersymmetric model is fine-tuned under all three measures so that it is unlikely to contain the UTH. The nonuniversal Higgs model NUHM2 appears fine-tuned with \ensuremathΔHS,BG\ensuremath\gtrsim103. But since \ensuremathΔEW can be as small as 7 (corresponding to 14% fine-tuning), it may contain the UTH for parameter ranges which allow for low true EWFT.