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Phenomenology of the Singlet Extended Standard Model

Phenomenology of the Singlet Extended Standard Model. Mat McCaskey with V. Barger, P. Langacker, M. Ramsey-Musolf, and G. Shaughnessy. Pheno2007 May 8th, 2007. SM Higgs + Scalar Singlet. Add one singlet to the Higgs potential Higgs is indistinguishable from SM

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Phenomenology of the Singlet Extended Standard Model

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  1. Phenomenology of the Singlet Extended Standard Model Mat McCaskey with V. Barger, P. Langacker, M. Ramsey-Musolf, and G. Shaughnessy Pheno2007 May 8th, 2007

  2. SM Higgs + Scalar Singlet Add one singlet to the Higgs potential • Higgs is indistinguishable from SM • Singlet is shifted so it obtains no VEV -Singlet only couples to the Higgs Two specific cases to study Case 1: Singlet couples to the Higgs (O’Connell et al.) Case 2: Impose reflection symmetry (McDonald & Burgess et al.)

  3. Case 1: Higgs and Singlet Mixing Higgs BF same as SM Exception: mH2> 2mH1 then H2  H1 H1 is open Higgs coupling reduced universally by mixing parameter BF of H1 same as SM Higgs of equal mass

  4. Case 1: New Higgs decay modes Extended decays through singlet: WH lv + 4b WHlv + 2b + 2

  5. Case 1: New Higgs decay modes

  6. Case 2: Reflection Symmetry • S-S symmetry prevents S decay • DM candidate • DM singlet annihilates through the Higgs boson via Annihilation processes:

  7. Case 2: Higgs decay to singlet • Higgs decays to invisible states which reduces the rate of traditional modes.

  8. Case 2: Finding invisible Higgs • Weak boson fusion: • Extract signal with cuts on azimuthal correlation of forward jets and large missing pT • Z-Higgstrahlung: • Cuts on di-lepton separation and invariant mass extract signal • Combined model independent Higgs mass determination. Eboli and Zeppenfeld Davoudiasl, Han, Logan

  9. Case 2: Relic Density • Numerically solved Boltzman equation (McDonald et al., Gondolo et al., Kolb and Turner)

  10. Case 2: Relic Density • WMAP constrains the relic density to be between 0.099 < Sh2 < 0.123

  11. Case 2: Scattering Cross Section • Direct detection of the dark matter candidate by elastic scattering off a nucleus.

  12. Case 2: Higgs discovery via stable S • OPAL: Higgs w/SM couplings mh>82 GeV • ATLAS reach on BF(Hinv.) to ~ 20% Higgs can be discoverable through visible or invisible modes with early LHC data.

  13. Summary SM + 1 scalar singlet: Case 1: Singlet Mixes with SM Higgs -Traditional discovery modes weakened if H2  H1 H1 is open -Higgs discovery may be possible with new decay modes through new modes. Case 2: Reflection Symmetry (Stable S) -DM Candidate -Visible discovery modes weakened from HSS. -Higgs may be discoverable through invisible modes.

  14. Parameter Scan Ranges Case 1 Case 2

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