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

2. 2 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma  MSSM: 2 Higgs doublets  5 Bosons: 3 neutral + 2 charged  at Born level: 2 parameters tanv 2 /v 1 and M A (or M H+ ) CP conserved  2 neutral CP-even h,H + 1 CP-odd A mass prediction: M h < M Z (already excluded by LEP) The MSSM Higgs Sector in the Nutshell  t b/ W/Z h cossin-sincossin() H sinsincos/coscos() A cottan -----  g MSSM = g SM  no coupling of A to W/Z  small   small BR(h  ,bb)  large    large BR(h,H,A  ,bb)  = mixing btw. CP-even neutral Higgs bosons

3. 3 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma The MSSM Higgs Sector in the Nutshell  mainly influence masses and couplings of h  phenomenology of heavy states very similar  depending on 105 additional MSSM parameters and m top  too many  „constrained“ MSSM: X t, M 0, M 2, M gluino,   mass prediction M h < 133/136GeV (for M t =175/178 GeV)   Born   effective  benchmark scenarios: fix X t, M 0, M 2, M gluino,  goal: design difficult and challenging scenarios e.g. low / high values of M h, suppressed couplings if X t,…real  Higgs sector CP-conserving h, H, A complex  Higgs sector CP-violating H 1, H 2, H 3  large loop corrections to masses and couplings

4. 4 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma  MHMAX scenario maximal m h < 133/6 GeV  conservative LEP exclusion  Nomixing scenario Benchmark Scenarios Carena et al., Eur.Phys.J.C26,601(2003 )  Gluophobic scenario  Small  scenario  4 CP conserving scenarios  1 CP violating scenario: CPX (Carena et al., Phys.Lett B495 155(2000)) today: discuss only MHMAX and CPX scenario same tan/M A point: shift of 17 GeV: MHMAX  Nomix shift in M t ~ shift in M h

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

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

7. 7 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Discovery Potential in the tanversus M A Plane LEP tan exclusion: no exclusion for m t larger ~183 GeV !  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 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?

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

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

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

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

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

13. 13 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Light Higgs Boson h: 300 fb -1 (VBF only 30 fb -1 )  large area covered by several channels  sure discovery and parameter determination  small area uncovered @ m h = 90 to 100 GeV (same conclusion in other 3 CPC scenarios) 300 fb -1 30 fb -1 previous channels + H  + bbh, H   (no BG sys, M t =178GeV)

14. 14 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 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 M t =175 GeV considered. Negligible effect expected forM t =178GeV.

15. 15 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Heavy Neutral Higgs Bosons large tan covered by bbH/A, H/A   ~ (tan) 2  coverage similar in 3 other scenarios  reminder: tanexclusion depends on m top, here 175 GeV  running b-quark mass for Xsec.  QCD scale = (M h +m b /4)  intermediate tan maybe coverable in parts by SUSY decays: H/A           4 l +- ?

16. 16 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Charged Higgs Bosons gb  H +- t H +-   t  bqq low mass: m H+- < m top gg  tt tt  H +- bW only low lumi. high mass: m H+- > m top  transition region around m top needs revised experimental analysis  running bottom quark mass used ( Xsec for gb  tH +- from T. Plehn‘s program)  intermediate tan maybe coverable in parts by SUSY decays: H           3 l +- ? +-

17. 17 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 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? similar results in other benchmark scenarios VBF channels, H/A  only used with 30fb -1 300 fb -1

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

19. 19 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma The CP violating CPX scenario  maximise effect  CPX scenario (Carena et al., Phys.Lett B495 155(2000)) arg(A t )=arg(A b )=arg(M gluino )=90 degree  scan of Born level parameters: tan and M H+-  CP eigenstates h, A, H mix to mass eigenstates H 1, H 2, H 3  CP conserving at Born level, but CP violation via complex A t, A b M gl

20. 20 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Phenomenology in the CPX scenario  H 1,H 2, H 3 couple to W,Z H3 H2 H1  H 2,H 3  H 1 H 1, ZH 1, WW, ZZ decays sum rule:  i g i (ZZH i ) = g SM LHWG-Note 2004-01  no absolute limit on mass of H 1 from LEP  strong dependence of excluded region on value for m top on calculation used FeynHiggs vs CPH 2 2

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

22. 22 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Overall Discovery potential in CPX Scenario size of „hole“ depends on  assumed M t due to LEP exclusion  program for calculation used FH versus CPSUPER M H1 : < 70 GeV M H2 : 105 to 120 GeV M H3 : 140 to 180 GeV small masses below 70 GeV not yet studied in ATLAS Small uncoverd region ! 300 fb -1 promising channel: tt  bH + bW - H +  H 1 W + H 1  bb, sáme final state as ttH, H  bb 1st look at Les Houches05, ongoing Diploma thesis

23. 23 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma Conclusions 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  CP-conserving MSSM:  probably „hole“ as M h below 70 GeV no studied yet in ATLAS  check sensitivity tt  Wb H +- b,H +  WH 1  Wbb  continue comparison of calculations and m top dependence  whole parameter space covered by at least one Higgs boson evaluation of discovery potenital with sys. err. in progress  only h observable at intermediate tan ongoing studies for SUSY decay modes and discrimination between SM and beyond via parameter meas.  CP-violating MSSM:

24. 24 M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma MC Studies with Discovery Potential channellumimass rangepublication VBF, H  WW lowM>110 GeV SN-ATLAS-2003-024 ttH, H  bb *low+highM>70GeV ATL-PHYS-2003-003 bbH/A   low+high70<M<135GeV M> 120 GeV ATL-PHYS-2002-021 ATL-PHYS-2000-005 bbH/A    lep.had   had. had. low M >120 GeV M > 450 GeV ATL-PHYS-2000-001 ATL-PHYS-2003-009 ATL-PHYS-2003-003 WW  ll low+high140<M <120GeV ATL_PHYS-2000-015 H   low+highM > 70 GeV TDR ZZ  4llow+highM > 100 GeV TDR A  Zh  llbb, H  hh  bb low+high60 <ML<130 100<MH<360TDR H/A  ttlow+highM > 350 GeV TDR gb  tH+-, H  ,tb low+highM >180 GeV SN-ATLAS-2002-017 tt  bW bH+-, H+-   lowM < 170 GeV ATL-PHYS-2003-58/TDR * ttH, H  bb at high. lumi see MSSM note