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Discovery Potential for MSSM Higgs Bosons with ATLAS

Johannes Haller (CERN) on behalf of the ATLAS collaboration. International Europhysics Conference on High Energy Physics, July 21 st -27 th 2005, Lisbon, Portugal. Discovery Potential for MSSM Higgs Bosons with ATLAS. MSSM Higgs Sector.

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Discovery Potential for MSSM Higgs Bosons with ATLAS

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  1. Johannes Haller (CERN) on behalf of the ATLAS collaboration International Europhysics Conference on High Energy Physics,July 21st-27th 2005, Lisbon, Portugal Discovery Potential for MSSM Higgs Bosons with ATLAS

  2. MSSM Higgs Sector • MSSM: 2 Higgs doublets  5 physical bosons: h, H, A, H+, H- • phenomenology at Born level described by tanb, m A • mass prediction: Mh < MZ • couplings: gMSSM = ξ· gSM • no coupling of A to W/Z • large tanb: large BR(h,H,Att,bb) a: mixing angle between CP even Higgs bosons (calculable from tanb and MA) • large loop corrections to masses and couplings • mainly dependent on t/ t sector • parameters: • Mtop and Xt, MSUSY, M2, m, Mgluino • mass prediction Mh < 133 GeV • (for Mt = 175GeV) ~ for exclusion bounds and discovery potential: fix the 5 parameters in benchmark scenarios and scan (tanb, MA)- plane MSSM Higgs Bosons with ATLAS

  3. The (tanb, MA)-Plane • current exclusion in (tanb,MA)-plane: • LEP excludes low tanb and low MA region • note: no exclusion from LEP • for Mt larger ~183 GeV main questions for LHC/ ATLAS: • Can at least 1 Higgs be discovered in the allowed parameter space? • How many Higgs bosons can be observed ? • Can the SM be discriminated from models with extended Higgs sectors (like MSSM) ? MSSM Higgs Bosons with ATLAS

  4. Benchmark Scenarios • 4 CP conserving scenarios considered • to examplify the discovery potential • mainly influence on phenomenology of h eff. hg - coupling suggested by Carena et al., EPJ C26, 601(2003) • MHMAX scenariomaximal Mh < 133 GeV • Nomixing scenariosmall Mh < 116 GeV • Gluophobic scenarioMh < 119 GeV • coupling of h to gluons suppressed • designed to affect discovery via • gg h, hgg and hZZ 4l • Small a scenarioMh < 123 GeV • coupling of h to b (t) suppressed • (for large tanb and MA 150500GeV) • designed to affect discovery via • VBF, htt and tth, hbb already at LEP hbb - coupling Newly designed for hadron colliders masses, coupling and BRs calculated with FeynHiggs (Heinemeyer et al.) MSSM Higgs Bosons with ATLAS

  5. Technical Issues • combination of latest results from (MSSM corrected) studies for SM Higgs boson (see talk of P.Conde) and dedicated MSSM Higgs analysis (heavy higgs states) • key performance numbers obtained from full simulation: (e.g. trigger efficiencies, b-tagging, t- identification, mass resolutions ...) • signal efficiencies and background expectations from fast simulations LO SM prod. cross section (M. Spira) corrected with FeynHiggs  conservative! • developments/ improvements: • new and updated search channels: • new: VBF with Higgs decay to tt, WW, gg. • new: ttbW+bHbqq+btn • updated: ttH, Hbb (better simulation of bgr.) • updated/ new: bbHHmm (tt), now also had. t decay • improved theoretical calculations: • FeynHiggs: full one-loop corrections and dominant two-loop corrections included (increase of Mh by several GeV) •  considered to give most accurate calculations at present • two expected data sets: 30 fb-1 and 300 fb-1 • discovery = 5 s excess using Poisson statistics • no systematics included MSSM Higgs Bosons with ATLAS

  6. Light Higgs Boson (30 fb-1) See talk of P. Conde for SM Higgs searches with ATLAS h observable in entire parameter space and for all benchmark scenarios? ATLAS (prel.) ATLAS (prel.) ATLAS (prel.) • most important channels: VBF • differences mainly due to Mh almost entire (tanb, MA)- plane covered MSSM Higgs Bosons with ATLAS

  7. Light Higgs in Small a Scenario (30 fb-1) hole due to reduced BR for H tt covered by enhanced BR to gauge bosons ATLAS (prel.) ATLAS (prel.) Complementarity of search channels almost guarantees the discovery of h MSSM Higgs Bosons with ATLAS

  8. Light Higgs Boson (300 fb-1) ATLAS (prel.) VBF: only 30 fb-1 ATLAS (prel.) • also hgg, hZZ4 leptons, tthbb contribute • large area coveredby several channels •  stable discovery and parameter determination possible • small area uncovered (Mh = 90 to 100 GeV) MSSM Higgs Bosons with ATLAS

  9. Neutral Heavy Higgs Bosons (H/A) • example: bbH/A, H/A  tt discovery reach for H/A: • sprod ~ (tanb)2; important at large tanb • new analysis: tt had. had. • BR(H/Att) ~ 10 % , rest is bb ATLAS (prel.) rec. mass for tthad.had. 30fb-1 ATLAS (prel.) New: take running b- quark mass for s prod • bb H/A bb tt covers large tanb region • other scenarios similar • intermediate tanb region not covered • only very few events remain after cuts (acceptance ~10-3) • LVL1 trigger performance crucial • detailed study: >90% LVL1 efficiency for MA>450GeV via “jet+ET,miss” and “t+ ET,miss” triggers with a rate of ~1.4 kHz (within rate limit) MSSM Higgs Bosons with ATLAS

  10. Overall Discovery Potential (300 fb-1) 300 fb-1 • at least one Higgs boson is observable for all parameter points (in all four benchmark scenarios) • in some parts: >1 Higgs bosons observable  distinguish between SM and extended Higgs sector • but: significant area where only h is observable. • basic conclusions independent of mtop ATLAS (prel.) VBF channels, H/Att only 30fb-1 ongoing: • including SUSY decay modes to increase areas for heavy Higgs bosons , e.g. H1,201,2,3,4 3l + ET,miss • can SM be discriminated from extended Higgs sector by parameter determination e.g. via rate measurements? MSSM Higgs Bosons with ATLAS

  11. Summary • A consistent investigation of the ATLAS discovery potential in the MSSM Higgs sector with new MC studies and new theoretical calculations has been performed. • In all 4 CP conserving MSSM benchmark scenarios at least one Higgs boson can be discovered. • In some areas of the parameter space more than one Higgs bosons can be discovered. direct discrimination between SM and extended Higgs sector MSSM Higgs Bosons with ATLAS

  12. Back-up slides MSSM Higgs Bosons with ATLAS

  13. SM or extended Higgs Sector ? • estimate of sensitivity from rate measurements in VBF channels (30 fb-1) • compare expected measurement of R in MSSM with prediction from SM BR(h WW) BR(h tt) R = D=|RMSSM-RSM|/sexp ATLAS (prel.) ATLAS (prel.) • potential for discrimination • seems promising • needs further study incl. sys. errors • only statistical errors • assume Mh exactly known MSSM Higgs Bosons with ATLAS

  14. Charged Higgs Bosons MSSM Higgs Bosons with ATLAS

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