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Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS

Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS. Markus Schumacher. The MSSM Higgs Sector in the Nutshell. MSSM: 2 Higgs doublets  5 Bosons: 3 neutral + 2 charged at Born level: 2 parameters tan b= v 2 /v 1 and M A (or M H+ )

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Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS

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  1. Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS Markus Schumacher

  2. The MSSM Higgs Sector in the Nutshell • MSSM: 2 Higgs doublets  5 Bosons: 3 neutral + 2 charged • at Born level: 2 parameters tanb=v2/v1 and MA (or MH+) CP conserved  2 neutral CP-even h,H + 1 CP-odd A mass prediction: Mh < MZ(already excluded by LEP) • gMSSM = xgSM • no coupling of A to W/Z • small a  small BR(htt,bb) • large b  large BR(h,H,Att,bb) a = mixing btw. CP-even neutral Higgs bosons M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  3. The MSSM Higgs Sector in the Nutshell • large loop corrections to masses and couplings • depending on 105 additional MSSM parameters and mtop • too many  „constrained“ MSSM: Xt, M0, M2, Mgluino, m • mass prediction Mh < 133/136GeV (for Mt=175/178 GeV) • aBorn  aeffective • benchmark scenarios: fix Xt, M0, M2, Mgluino, m goal: design difficult and challenging scenarios • e.g. low / high values of Mh, suppressed couplings • if Xt,…real Higgs sector CP-conservingh, H, A • complex  Higgs sector CP-violating H1, H2, H3 • mainly influence masses and couplings of h • phenomenology of heavy states very similar M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  4. Benchmark Scenarios • 4 CP conserving scenarios Carena et al. , Eur.Phys.J.C26,601(2003) • MHMAX scenariomaximal mh < 133/6 GeV  conservative LEP exclusion • Nomixing scenario • Gluophobic scenario • Small a scenario same tanb/MA point: shift of 17 GeV: MHMAX  Nomix shift in Mt ~ shift in Mh • 1 CP violating scenario: CPX (Carena et al., Phys.Lett B495 155(2000)) today: discuss only MHMAX and CPX scenario M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  5. Signal and Background Rates 1)SM production cross sections times MSSM correction factors (FH) • LO with CTEQ5L (no K-factors!) • running b-quark mass for bbh(/H/A) and gbtH+ 2)branching ratios from FeynHiggs 3)efficiencies and background expectations from documented ATLAS MC studies M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  6. Corrections to Expected Signal Rates 4) for part of MSSM parameter space: large Gtot  eMSSM = K eSM K = h convolution of BW with Gaussian mass resolution 5)signal overlap due to mass degeneracy of Higgs bosons count signal in mass window 1 = signal 1 + signal 2 in window 1 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  7. Discovery Potential in the tanb versus MA Plane main questions for ATLAS: • At least 1 Higgs boson observable in the entire parameter space? • How many Higgs bosons can be observed? • Can the SM be discriminated from extended Higgs sectors? • two expected data volumes 30 fb-1 300 fb-1 = 30 fb-1@ low lumi. + 270fb-1 @high lumi • discovery = 5 sigma excess using Poissonian statistics LEP tanb exclusion: no exclusion for mt larger ~183 GeV ! M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  8. Discovery potential for light Higgs boson h • observation in entire parameter space ? • several channels observable? new since February Plenary: study effect of Mt: 175  178 GeV of systematic uncertainty on background For comparison of different benchmark scenarios see talk at February plenary. Basic conlusions are the same. M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  9. Vector Boson Fusion H  tt effect of DBG=10% effect of Mt: 175 vs 178 w/o sys DBG • h or H observable with 30 fb-1 over allmost whole plane • small effect due to background uncertainty • enlarged coverage for Mt=178, but weaker LEP exclusion studied for MH>110GeV at low lumi running M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  10. Vector Boson Fusion H  WW effect of DBG=10% effect of Mt: 175 vs 178 • small effect due to background uncertainty • enlarged coverage for Mt=178, but weaker LEP exclusion studied for MH>110GeV at low lumi running M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  11. H  ZZ  4 leptons effect of DBG=10% effect of Mt: 175 vs 178 w/o sys DBG effect due to background uncertainty decreasing with int. lumi for Mt=178 GeV observation already possible with 30 fb-1 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  12. tth hbb SM • strong dependence of significance on Mh •  plane covered in „No mixing“ and other scenarios • No discovery potential with 300 fb-1 when including DBG=10%! • (need cross check with 2nd statistic program and for other bechmarks) M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  13. Light Higgs Boson h: 300 fb-1 (VBF only 30 fb-1) previous channels +Hgg +bbh, Hmm (no DBGsys,Mt=178GeV) 300 fb-1 • large area coveredby several channels  sure discovery and parameter determination • small area uncovered @ mh = 90 to 100 GeV (same conclusion in other 3 CPC scenarios) 30 fb-1 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  14. SM Higgs sector or extended one ? • observation of additional Higgs boson (H/A/H+-) • deviation of properties of h from SM prediction No systematic uncertainties for background expectation included yet. Only Mt=175 GeV considered. Negligible effect expected forMt=178GeV. M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  15. Heavy Neutral Higgs Bosons large tanb covered by bbH/A, H/Att,mm s ~ (tanb)2 • running b-quark mass for Xsec. • QCD scale = (Mh+mb/4) • intermediate tanb maybe coverable in parts by SUSY decays: H/Ac2c2c1c1+4 l+- ? • coverage similar in 3 other scenarios • reminder: tanb exclusion depends on mtop, here 175 GeV M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  16. Charged Higgs Bosons high mass: mH+-> mtop gbH+-t H+-tn tbqq low mass: mH+-< mtop ggtt ttH+-bW only low lumi. • transition region around mtopneeds revised experimental analysis • running bottom quark mass used (Xsec for gbtH+- from T. Plehn‘s program) • intermediate tanb maybe coverable in parts by SUSY decays: Hc2c1c1c1+3 l+- ? +- M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  17. Overall Discovery Potential: 300 fb-1 • at least one Higgs boson over hole plane in all four CPC scenarios • significant area where only lightest Higgs boson h is observable questions for future studies: • can SUSY decay modes provide observation? • can SM be discriminated from extended Higgs sector by parameter determination? 300 fb-1 similar results in other benchmark scenarios VBF channels , H/Att only used with 30fb-1 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  18. SM or Extended Higgs Sector ? • estimate of sensitivity from rate measurements in VBF channels (30fb-1) • compare expected measurement of R in MSSM with prediction from SM BR(h WW) BR(h tt) D=|RMSSM-RSM|/sexp R = 300 fb-1 • potential for discrimination • seems promising • needs further study incl. sys. errors • only statistical errors • assume Mh exactly known M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  19. The CP violating CPX scenario • CP conserving at Born level, but CP violation via complex At, Ab Mgl • CP eigenstates h, A, H mix to mass eigenstates H1, H2, H3 • maximise effect  CPX scenario(Carena et al., Phys.Lett B495 155(2000)) • arg(At)=arg(Ab)=arg(Mgluino)=90 degree • scan of Born level parameters: tanb and MH+- M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  20. Phenomenology in the CPX scenario • H2,H3 H1H1, ZH1,WW, ZZdecays • H1,H2, H3 couple to W,Z H1 sum rule: Si gi (ZZHi) = gSM 2 H2 2 H3 • no absolute limit on mass of H1 from LEP • strong dependence of excluded region on value for mtop on calculation used FeynHiggs vs CPH LHWG-Note 2004-01 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  21. CPX Scenario: Light Higgs Boson H1 300 fb-1 • border at low tanb due to availability of MC studies (VBF: Mh >110 GeV, ttH and gg :Mh> 70 GeV) • border at low MH+- due to decoupling of H1 from W,Z and t main difference to CPC scenarios: weaker exclusion from LEP data CPC scenarios: Mh< MZ excluded CPV: no limit on MH1 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  22. Overall Discovery potential in CPX Scenario 300 fb-1 Small uncoverd region ! MH1: < 70 GeV MH2: 105 to 120 GeV MH3: 140 to 180 GeV small masses below 70 GeV not yet studied in ATLAS size of „hole“ depends on • assumed Mt due to LEP exclusion • program for calculation used FH versus CPSUPER promising channel: tt bH+bW- H+H1 W+ H1bb, sáme final state as ttH, Hbb 1st look at Les Houches05, ongoing Diploma thesis M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  23. Conclusions • CP-conserving MSSM: • whole parameter space covered by at least one Higgs boson evaluation of discovery potenital with sys. err. in progress • only h observable at intermediate tanb ongoing studies for SUSY decay modes and discrimination between SM and beyond via parameter meas. • CP-violating MSSM: • probably „hole“ as Mh below 70 GeV no studied yet in ATLAS • check sensitivity ttWb H+- b,H+WH1Wbb • continue comparison of calculations and mtop dependence Thanks to: P. Bechtle, T. Hahn, S. Heinemeyer, J.S. Lee, A. Pilaftsis, T. Plehn, D.avid Rainwater, M. Spira, G. Weiglein and ATLAS Higgs WG M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

  24. MC Studies with Discovery Potential *ttH, Hbb at high. lumi see MSSM note M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma

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