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Probing the Higgs sector at the LHC

Probing the Higgs sector at the LHC. SM Higgs detection at the LHC inclusive signals – brief review exclusive diffractive signals pp  p + H + p calculation of H bb bar signal and background

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Probing the Higgs sector at the LHC

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  1. Probing the Higgs sector at the LHC • SM Higgs detection at the LHC inclusive signals – brief review exclusive diffractive signals pp  p + H + p calculation of H bbbar signal and background “standard” candles at Tevatron: excl. c, gg, jj prod. • Higgs detection in MSSM Motivation for SUSY --- Higgs sector in SUSY exclusive diffractive signals --- advantages — 0--,0+ analysis CP violation in the Higgs sector University of Louvain, February 2005 Alan Martin (IPPP,Durham)

  2. also gg H

  3. SM

  4. difficult region

  5. difficult region

  6. Branching fractions of SM Higgs

  7. A low mass Higgs (<130 GeV) is difficult to identify Hbb is dominant decay, but is swamped by the QCD background

  8. Branching fractions of SM Higgs

  9. Total width of SM Higgs G=1 GeV MH=120 GeV

  10. pp p + H + p H bb

  11. no emission when (l ~ 1/kt) > (d ~ 1/Qt) i.e. only emission withkt > Qt

  12. calculated using detailed 2-channel eikonal global analysis of soft pp data S2 = 0.026 at LHC S2 = 0.05 at Tevatron Lonnblad Monte Carlo S2 = 0.026 S2 = 0.040 MH=120GeV

  13. + collinearity + “gapiness”

  14. If the bulk of the events are in DMmissing=1GeV

  15. possible Tevatron “standard candles”

  16. ppp + gg + p KMR+Stirling

  17. KMR+Stirling Diffractive c production only order-of-magnitude estimates possible for c production

  18. BSM: motivation for weak scale SUSY Can stabilize hierarchy of mass scales: dMh2 ~ g2(mb2-mf2) Gauge coupling unification (at high scale, but < Planck) Provides a candidate for cold dark matter (LSP) Could explain the baryon asymmetry of the Universe SUSY effects at present energies only arise from loops-- so the SM works well Provides an explanation for Higgs mechanism (heavy top) The Higgs sector is the natural domain of SUSY. Higgs vev induced as masses are run down from a more symmetric high scale There must be a light Higgs boson, Mh < 140 GeV

  19. mt=174.3 GeV  178 GeV

  20. Mh < 140 Weiglein

  21. H and h widths, compared to SM Higgs H --> hh and tt thresholds

  22. <- ->

  23. Exclusive diffractive MSSM Higgs production Spin-parity analysis use angle j between two outgoing protons in the transverse plane to distinguish 0-- from 0+

  24. ppp1 + higgs + p2 higgs

  25. rescatt. corr. omitted S2=1

  26. more peripheral p1T,p2T correlations reflect spin-parity of central system: can distinguish 0-- from 0+ pp  p1 + H + p2

  27. wedge

  28. decoupling regime: mA ~ mH large h = SM intense coup: mh ~ mA ~ mH gg,WW.. coup. suppressed

  29. SM: pp  p + (Hbb) + p S/B~11/4 with DM = 1 GeV, at LHC with 30 fb-1 e.g. mA = 130 GeV, tan b = 50 (difficult for conventional detection, but exclusive diffractive favourable) S B mh = 124.4 GeV 71 3 events mH = 135.5 GeV 124 2 mA = 130 GeV 1 2 enhancement

  30. 5s signal at LHC 30 fb-1 300 fb-1

  31. Motivation for CP-Violation in SUSY Models • In low energy SUSY, there are extra CP-violating phases beyond the CKM ones, associated with complex SUSY breaking parameters. • One of the most important consequences of CP-violation is its possible impact on the explanation of the matter-antimatter asymmetry. • Electroweak baryogenesis may be realized even in the simplest SUSY extension of the SM, but demands new sources of CP-violation associated with the third generation sector and/or the gaugino-Higgsino sector. • At tree-level, no CP-violating effects in the Higgs sector---CP violation appears at loop-level

  32. gives the mixing between would-be CP-odd and CP-even sates, predominantly governed by stop induced loop effects Higgs Potential  Quantum Corrections Main effect of CP-Violation is the mixing of the three neutral Higgs bosons In the base Gluino phase relevant at two-loop level. Guagino effects may be enhanced for large tan beta

  33. CPX scenario: no lower bound on MH1 from LEP! • H1 decouples from the Z and H2 and H3 may be out of kinematic reach. • or reduced couplings of Hi to Z and extended regions were H2 decays H1H1 and the H1’s decay into b’s mH2 < 130 GeV  major role of CP-violating effects Example: mH1 = 45 GeV, mH2 = 110 GeV, Not excluded No Universal lower limit on mH1 but (mt dep.) Including with in the analyses

  34. Br.s in (fb) for H1, H2, H3 production at the LHC fb S/B~M-5 cuts: (a) 60<q(b or t)<1200, (b) piT>300 MeV, (c) 45<q(b)<1350

  35. Allow p’s to dissociate Larger signal---but no sQCD(bb) suppression, so use H1 tt (…) EiT>7 GeV fb p1T j p2T 1 + a sin 2j + b cos 2j if CP cons. then a=0, |b|=1

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