SO(10) as a framework for natural supersymmetry

Abstract

We consider an SO(10) grand unified theory in which the ratio of the SU (2) W and SU (3) c gaugino masses satisfy M 2 /M 3 ≈ 3, which results in the realization of natural supersymmetry. In the MSSM parameter space this relation looks artificial, but in the SO(10) case it results from a field with a designated vacuum expectation value. We consider two models, namely M 1 : M 2 : M 3 = −1/5 : 3 : 1 (Case I), and M 1 : M 2 : M 3 = −5 : 3 : 1 (Case II). Focusing on ameliorating the little hierarchy problem, we explore the parameter space of these models which yield small fine-tuning measuring parameters (natural supersymmetry) at the electroweak scale (∆ EW ) as well as at the high scale (∆ HS ). Although both models allow for the solution of the little hierarchy problem, the predicted sparticle spectra can differ markedly in the two cases. Depending on the ratio of the bino mass to the other gaugino masses, Case I leads to stau lepton masses of around a 100 GeV, while in Case II, the stau slepton masses are in the several TeV range. In Case I, the bino-like neutralino can be as light as 90 GeV, while the gluino is heavier than 2 TeV or so. In Case II, due to gluinobino near degeneracy, the bino cannot be lighter than a TeV or so. Having a light neutralino with sizable bino-higgsino mixture in Case I allows the direct dark matter search experiments to test this class of models.

Light stops and fine-tuning in MSSM

“…In this sense, the fine-tuning requirement can emerge because of some missing mechanisms, and its amount can be interpreted as the effectiveness of these missing mechanisms, and also indicates the amount of deviation from the minimality. The effects from missing mechanisms can be analyzed also within the MSSM framework by implementing non-universalities in gaugino and scalar sectors [28][29][30][31] In our work, we analyze the effects of possible missing mechanisms within the MSSM framework by imposing non-universality in the gaugino sector. While we focus on the regions with low fine-tuning, we also highlight the stop masses less than 700 GeV, and discuss if such solutions can still survive under the severe experimental constraints.…”

Low fine-tuning in Yukawa-deflected gauge mediation

“…However, this also makes it very difficult to test even in the long run. A similar conclusion is shared in the context of gravity mediation by grand unified theory (GUT) models with the non-universal gaugino masses induced by the breaking of the GUT group [12][13][14][15][16][17][18][19].…”

A realistic intersecting D6-brane model after the first LHC run

“…We note that for µ < 0 case the minimal value of ∆ HS is 1125 (0.08% FT) with ∆ EW value of 297(0.33% FT), while we have 963(0.1% FT) and 285(0.35% FT) for ∆ HS and ∆ EW respectively for µ > 0. It was shown in dedicated studies of natural supersymmetry [84,85] that with the above definitions of ∆ EW and ∆ HS it is possible to have values for both the measures 50 simultaneously.…”