Horizontal, anomalous U(1) symmetry for the more minimal supersymmetric standard model

Abstract

We construct explicit examples with a horizontal, ''anomalous'' U͑1͒ gauge group, which, in a supersymmetric extension of the standard model, reproduce qualitative features of the fermion spectrum and CKM matrix, and suppress FCNC and proton decay rates without the imposition of global symmetries. We review the motivation for such ''more'' minimal supersymmetric standard models and their predictions for the sparticle spectrum. There is a mass hierarchy in the scalar sector which is the inverse of the fermion mass hierarchy. We show in detail why ⌬Sϭ2 FCNCs are greatly suppressed when compared with naive estimates for nondegenerate squarks. ͓S0556-2821͑97͒04215-X͔ PACS number͑s͒: 12.60. Jv, 14.80.Ly The minimal supersymmetric standard model ͑MSSM͒ with top-squark-induced electroweak symmetry breaking naturally stabilizes the electroweak scale, but fails to exhibit the accidental global symmetries of the standard model ͑SM͒ which inhibit flavor-changing neutral currents ͑FCNCs͒, lepton flavor violation ͑LFV͒, electric dipole moments ͑EDMs͒, and proton decay. To agree with experimental bounds, such processes must be suppressed by imposing approximate global symmetries to produce degeneracy or alignment in the squark and slepton mass matrices. Recently, Cohen, Kaplan, and Nelson ͓1͔ have proposed an alternative framework in which the gauginos, Higgsinos, and third generation squarks are sufficiently light to naturally stabilize the electroweak scale, while the first two generations of squarks and sleptons are sufficiently heavy to suppress FCNC, LFV, and EDMs below experimental bounds. Such models are ''more'' minimally supersymmetric than the MSSM in the sense that they do not require the ad hoc supposition of degeneracy or alignment. The anomalous U͑1͒ X used by Dvali and Pomarol ͓2͔, and Binetruy and Dudas ͓3͔ ͑DPBD͒ to break supersymmetry could induce the required mass hierarchy, provided third generation matter carries no X charge. In this paper, we show that an anomalous U͑1͒ X can also explain the order of magnitude of fermion masses and mixing angles, and suppress proton decay from dimension-five operators. Our criteria for assigning U͑1͒ X charges differ significantly from those considered previously in this context ͓3,4͔.The DPBD mechanism of supersymmetry breaking requires a gauged U͑1͒ X with positively and negatively X-charged matter superfields P and N. If X symmetry is anomalous ͓i.e., tr(X) 0͔ below some scale M , the effective theory below this scale includes a Fayet-Iliopoulos term ϳg X 2 trXM 2 ͓5͔. For mathematical consistency, one can either imagine that M is the Planck scale and the anomaly is canceled via the Green-Schwarz mechanism ͓6͔, or that M is some other high scale at which anomaly canceling matter lives. If the superpotential also contains a term of the form mPN, introduced either explicitly or dynamically by nonperturbative physics, the various fields obtain vacuum expectation values: 1where ⑀ is given byThe D term vacuum expectation value ͑VEV͒ gives each scalar matter field a mass...

Inverted sfermion mass hierarchy and the Higgs boson mass in the MSSM

“…However, Tr(Y Q) has to vanish (or to be very small) for phenomenological reasons, as argued in various papers [45,46] and therefore our conclusions concerning the running of soft terms and the fine-tuning remain unchanged. In particular, for the charge assignment (3.8) S = 0 and the prediction for the Higgs boson mass are almost identical to those presented in the previous plots with degenerate first two generations.…”

Higgs boson mass and complex sneutrino dark matter in the supersymmetric inverse seesaw models

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