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Review of MSSM Higgs boson searches at LEP

Review of MSSM Higgs boson searches at LEP. MSSM with CP conservation MSSM with CP violation Conclusions. 3 neutral Higgs bosons: h, H, A CP-eigenstates at tree level, 2 parameters : tan , m A. CP-conserving MSSM scenarios. hZ: low tan  large tan & m A

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Review of MSSM Higgs boson searches at LEP

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  1. Review of MSSM Higgs boson searches at LEP MSSM with CP conservation MSSM with CP violation Conclusions 3 July 2006

  2. 3 neutral Higgs bosons: h, H, A CP-eigenstates at tree level, 2 parameters : tan, mA CP-conserving MSSM scenarios hZ: low tan large tan & mA HZ: large tan & low mA hA: interm./large tan & low mA Higgsdecays: invisible, , ee, , , KK, cc, , bb, AA, hadrons 3 July 2006

  3. The MSSM underlying parameters at higher order mtopand the SUSY breaking parameters, assumed to be unified at some scale : SU(2), U(1) gaugino mass terms unified at MGUT  M2 at MEW sfermion mass terms : unified at MEW  Msusyat MEW squark trilinear couplings : unified at MEW  A at MEW  mixing parameter in the stop sector :  X = A -  cot gluino mass and Higgs mixing parameter  Mğand Total: 8 parameters mtop is measured ; M2, Msusy, Mğ,  et X are chosen to define a “scenario”; tan and mA are free to vary (tan[0.4, 50] and mA[0.02, 1000] GeV). NB: radiative corrections in the Feynman-diagrammatic approach (the most complete at two-loop order) 3 July 2006

  4. mhmax: sparticules at high mass (M2, Msusy, Mğ large),  et X such that mh range is maximal (mtop=174.3 GeV: mh < 132.9 GeV). LHC variants: 1)   -, 2)   - & X  -X • No mixing: counterpart of mhmax with X=0;mh range reduced (mtop=174.3 GeV: mh < 115.5 GeV). LHC variant: 1)   -, Msusy  2 Msusy • Large : at least one Higgs (h, A or H) kinematically accessible (mtop=174.3 GeV: mh < 108.0 GeV) but Br(bb, ) vanish at large tan. • Gluophobicscenario:ggh (strongly) suppressed  tan, mA • Small eff: Brh(bb, ) suppressedat large tan, moderate mA The scenarios : 3 LEP / 5 LHC scenarios 3 July 2006

  5. mtop 95%CL 99.7%CL The mhmax scenario(s) mtop=174.3 GeV,95% CL limits: mh > 92.8 GeV, mA > 93.4 GeV insensitive to mtop tan exclusion : 0.7 – 2.0 sensitive to mtop LHC variants:~identical mass limits, looser tan constraints 3 July 2006

  6. unexcluded holes: hAA, mA<3GeV, mh~80GeV lack of searches at LEP2 The no mixing scenario(s) mtop=174.3 GeV,95% CL limits: mh, mA > 93.6 GeV (tan>0.7)tan exclusion : 0.4 – 10.2 (mA>3GeV) very sensitive to mtop: scenario fully excluded at mtop=169.3 GeV (H within reach) LHC variant: tighter mass and tan limits 3 July 2006

  7. The large  scenario • excluded at 95% CL, not at 99.7% CL: • hZ only remaining process • BR(hbb) suppressed • mh~108GeV close to the sensitivity of the flavour-blind searches This strip grows with increasing mtop theoretically forbidden mtop=174.3 GeV or smaller: scenario fully excluded at 95%CL thanks to: H searches and flavour-blind analyses 3 July 2006

  8. The gluophobic and small  scenarios mtop=174.3 GeV , 95% CL limits: mh > 90.5 GeV, mA > 96.3 GeV mh > 87.3 GeV, mA > 98.8 GeV tan exclusion : 0.4 – 5.4 tan exclusion : 0.4 – 4.2 moderately sensitive to mtop NB: h, A not degenerate in mass at large tan 3 July 2006

  9. CP-conserving MSSM scenarios, conclusions: • 8 representative scenarios scanned with ADLO results on neutral Higgs boson searches at LEP1 & LEP2 ; • improved sensivitivity thanks to H searches and flavour-blind analyses (esp. for low mtop) • mass limits are set atlarge tan and ~ O(90) GeV in mh,mA • tan limits are set by the LEP mhmax scenario : tan exclusion (95%CL) : 0.7 – 2.0 for mtop=174.3 GeV 3 July 2006

  10. 3 neutral Higgs bosons: H1,H2,H3mixtures ofCP-eigenstates at tree level, 2 parameters : tan, mH CP-violating MSSM scenarios H1H2: interm./large tan & low mH1 H1Z: low tan, large tan & mH1 H2Z: low/interm. tan & low mH1 wrt CPC case: more processes a priori, but some ZZHi couplings can be suppressed similar decays, but Hj HiHi is enhanced 3 July 2006

  11. The MSSM underlying parameters • The usual eight MSSM underlying parameters: • at tree level: tan, mH± • through radiative corrections : mtop and the SUSY breaking parameters: M2, Msusy, Mğ,  andAt,b • Additional CPV parameters : • two CPV phases : arg(At,b) and arg(Mğ) • Dominant CPV effects scale as: mtop4 Im(At,b)/(v12+v22)322Msusy2  low Msusy, large  and arg(At,b)~90o  the CPX scenario: Msusy=500GeV, =4Msusy=2TeV, |At,b|=Mğ=2Msusy=1TeV,M2=200GeV andarg(At,b)=arg(Mğ)=90o + 10 variants to study the dependence with arg(At,b),  and Msusy. NB: radiative corrections in the renormalization group and Feynman-diagrammaticapproaches(presently at the same stage of developpement) 3 July 2006

  12. 60° CPC ! 0° 90° slight excess of data lack of sensitivity Dependence with the CP-violating phases Phases ~90°:H1Z suppressed large tan: H1H2 interm.tan: H2Z, esp. H2 H1H1 3 July 2006

  13. 2TeV 1TeV 4TeV Dependence with  At intermediate tan: =1TeV: two processes left =2TeV: one process left =4TeV: no process left 3 July 2006

  14. 174.3GeV 169.2GeV 179.4GeV Dependence with mtop At intermediate tan: H1Z, H2Z and H1H2 suppression gets stronger with increasing mtop 3 July 2006

  15. CP-violating MSSM scenarios, conclusions: • 11 representative scenarios scanned with ADLO results on neutral Higgs boson searches at LEP1 & LEP2 ; • Significant effects require arg(At,b)=90°,135°, mtop174GeV, and |At,b|/ Msusy2 8 ; • CPV = redundancy lost reduced sensitivity of LEP at intermediate tan down to the lowest massesNo absolute mass limits! • tan limits are set by the CPX scenario : tan > 2.9 (95% CL) for mtop=174.3 GeV • Results are qualitatively the same in the renormalization group and Feynman-diagrammatic approaches. 3 July 2006

  16. Conclusions From the neutral Higgs boson searches at LEP applied to a set of representative MSSM scenarios : • If CP is conserved in the Higgs sector: • absolute mass limits around 90 GeV in mh,mA; • low tan region not favoured (0.7 – 2.0 excluded in theLEP mhmax scenariofor mtop=174.3 GeV). • If CP is not conserved in the Higgs sector: • No absolute mass limits (at intermediate tan) ! • low tan region still not favoured (tan<2.9 excluded in theCPX scenariofor mtop=174.3 GeV); • Calculations of radiative corrections not yet as complete as in the CP-conserving case. 3 July 2006

  17. Higgsstrahlung Pair-production (+ WW, ZZ fusion) Yukawa production Introduction Higgs boson searches at LEP: • Direct searches : • Only 3 production processes • Almost all decays can be exploited • model-independentconstraints on  x Br • model scans : SM, MSSM, 2HDM • Indirect constraints through EW precision measurements In this talk: SM + MSSM neutral Higgs boson direct searches published in April 2006 3 July 2006

  18. Current summary about the SM Higgs boson: EW precise measurements: MH ≤ 175 GeV (95% CL) Direct searches : MH ≥ 114.4 GeV (95% CL) MH [115,118] GeV ? (status as of spring 2006) 3 July 2006

  19. The Standard Model after LEP LEP results: New physics scale 3 July 2006

  20. 95% CL upper bounds on  x Br dominant decays : direct decays in bb or  H1Z H2H1 3 July 2006

  21. 95% CL upper bounds on  x Br non dominant decays : the example of the H2H1H1 cascade H2Z H2H1 3 July 2006

  22. The gluophobic and small  scenarios gluo. scen. small   Br(MSSM)/ Br(SM) predictions NB: tthttbb and WW fusion channels enhanced NB: h channel unsuppressed 3 July 2006

  23. weaker exclusion weaker exclusion CPH FeynHiggs CPH vs FeynHiggs more one-loop and two-loop order corrections in FeynHiggs phase dependence more complete in CPH than in FeynHiggs 3 July 2006

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