2006/07/31 by D. G. Cerdeno, David G Cerdeño, Athanasios Dedes +3
Computer Science · Physics and Astronomy · #Baryogenesis #Boson #Computational Physics and Python Applications #Electroweak interaction #Gauge boson #Goldstone boson #Higgs boson #Higgs mechanism #Higgs sector #Leptogenesis #Neutrino Physics Research #Particle physics theoretical and experimental studies #Technicolor #hep-ph
paper · pdf · doi:10.1088/1126-6708/2006/09/067
published as JHEP0609:067,2006 · 21 pages, 4 figures. Corrected typos and added references. To appear in JHEP
arxiv created 2006/09/12 · openalex publication_date 2006/09/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We propose the minimal, lepton-number conserving, SU(3)xSU(2)xU(1) gauge-singlet, or phantom, extension of the Standard Model. The extension is natural in the sense that all couplings are of O(1) or forbidden due to a phantom sector global U(1)D symmetry, and basically imitates the standard Majorana see-saw mechanism. Spontaneous breaking of the U(1)D symmetry triggers consistent electroweak gauge symmetry breaking only if it occurs at a scale compatible with small Dirac neutrino masses and baryogenesis through Dirac leptogenesis. Dirac leptogenesis proceeds through the usual out-of-equilibrium decay scenario, leading to left and right-handed neutrino asymmetries that do not fully equilibrate after they are produced. The model contains two physical Higgs bosons and a massless Goldstone boson. The existence of the Goldstone boson suppresses the Higgs to bb branching ratio and instead the Higgs bosons will mainly decay to invisible Goldstone and/or to visible vector boson pairs. In a representative scenario, we estimate that with 30 fb-1 integrated luminosity, the LHC could discover this invisibly decaying Higgs, with mass ~120 GeV. At the same time a significantly heavier, partner Higgs boson with mass ~210 GeV could be found through its vector boson decays. Electroweak constraints as well as astrophysical and cosmological implications are analysed and discussed.