The Minimal Supersymmetric Model without a μ term

Abstract

We propose a supersymmetric extension of the standard model which is a realistic alternative to the MSSM, and which has several advantages. No "µ" supersymmetric Higgs/Higgsino mass parameter is needed for sufficiently heavy charginos. An approximate U (1) R symmetry naturally guarantees that tan β is large, explaining the top/bottom quark mass hierarchy. This symmetry also suppresses supersymmetric contributions to anomalous magnetic moments, b → sγ, and proton decay, and these processes place no lower bounds on superpartner masses, even at large tan β. The soft supersymmetry breaking mass parameters can easily be obtained from either gauge or Planck scale mediation, without the usual µ problem. Unlike in the MSSM, there are significant upper bounds on the masses of superpartners, including an upper bound of 114 GeV on the mass of the lightest chargino. However the MSSM bound on the lightest Higgs mass does not apply.

Dirac gauginos and the 125 GeV Higgs

“…We take full advantage of the latter in investigating the "MSSM without µ term" [7] in section 6, comparing the results for ∆ρ with approximations given in [7]. Unfortunately those constraints in addition to those on chargino masses and the Higgs mass yield that model problematic.…”

“…In the presence of Dirac gaugino masses it is possible to remove the Higgsinos' mass term from the superpotential of the MSSM [7]. This is another way of curing the intrinsic µ-problem of the MSSM.…”

NSUSY fits

“…[53,54]. We will consider a minimal flavour violating scenario [55][56][57][58][59] when examining the NSUSY spectrum, this can follow from the argument above directly.…”

New calculations in Dirac gaugino models: operators, expansions, and effects

“…One such mechanism is the so called µ-less MSSM or / µMSSM. These models include superpotential terms, allowed by all symmetries, that couple the Higgs fields to the new SM adjoints [10]. These terms raise the tree level Higgs mass through the introduction of new quartic couplings.…”

“…This Higgs sector is quite complex, and variations of the Higgs potential in R-symmetric models have been recently been studied [19,21]. Our low energy superpotential will contain the Dirac-gaugino masses for the elctroweak sector as well electroweak adjoints coupling directly to the Higgs [10]. The low energy superpotential will then take the form…”