1. 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

2. Johannes HallerMSSM Higgs Bosons with ATLAS 2 large loop corrections to masses and couplings mainly dependent on t/ t sector parameters: M top and X t, M SUSY, M 2, , M gluino mass prediction M h < 133 GeV (for M t = 175GeV) large loop corrections to masses and couplings mainly dependent on t/ t sector parameters: M top and X t, M SUSY, M 2, , M gluino mass prediction M h < 133 GeV (for M t = 175GeV) MSSM Higgs Sector  MSSM: 2 Higgs doublets  5 physical bosons: h, H, A, H +, H -  phenomenology at Born level described by tan , m A  mass prediction: M h < M Z  couplings: g MSSM = ξ · g SM  no coupling of A to W/Z  large tan  large BR(h,H,A  ,bb)  MSSM: 2 Higgs doublets  5 physical bosons: h, H, A, H +, H -  phenomenology at Born level described by tan , m A  mass prediction: M h < M Z  couplings: g MSSM = ξ · g SM  no coupling of A to W/Z  large tan  large BR(h,H,A  ,bb) ξt b/  W/Z h cos  /sin  -sin  /cos  sin(  -  ) H sin  /sin  cos  /cos  cos(  -  ) A cot  tan  -----  : mixing angle between CP even Higgs bosons (calculable from tan  and M A ) for exclusion bounds and discovery potential: fix the 5 parameters in benchmark scenarios and scan (tan , M A )- plane for exclusion bounds and discovery potential: fix the 5 parameters in benchmark scenarios and scan (tan , M A )- plane ~

3. Johannes HallerMSSM Higgs Bosons with ATLAS 3 current exclusion in (tan ,M A )-plane:  LEP excludes low tan  and low M A region  note: no exclusion from LEP for M t larger ~183 GeV current exclusion in (tan ,M A )-plane:  LEP excludes low tan  and low M A region  note: no exclusion from LEP for M t 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) ? 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) ? The (tan , M A )-Plane

4. Johannes HallerMSSM Higgs Bosons with ATLAS 4 Benchmark Scenarios 1)MHMAX scenario maximal M h < 133 GeV 2)Nomixing scenario small M h < 116 GeV 3)Gluophobic scenario M h < 119 GeV coupling of h to gluons suppressed designed to affect discovery via gg  h, h   and h  ZZ  4l 4)Small  scenario M h < 123 GeV coupling of h to b (  ) suppressed (for large tan  and M A 150  500GeV) designed to affect discovery via VBF, h   and tth, h  bb 1)MHMAX scenario maximal M h < 133 GeV 2)Nomixing scenario small M h < 116 GeV 3)Gluophobic scenario M h < 119 GeV coupling of h to gluons suppressed designed to affect discovery via gg  h, h   and h  ZZ  4l 4)Small  scenario M h < 123 GeV coupling of h to b (  ) suppressed (for large tan  and M A 150  500GeV) designed to affect discovery via VBF, h   and tth, h  bb 4 CP conserving scenarios considered to examplify the discovery potential mainly influence on phenomenology of h masses, coupling and BRs calculated with FeynHiggs ( Heinemeyer et al. ) NameM SUSY (GeV)  (GeV) M 2 (GeV) X t (GeV) M gluino (GeV) m h -max1000200 2000800 no mixing2000200 0800 gluophobic350300 -750500 small  8002000500-1100500 suggested by Carena et al., EPJ C26, 601(2003) eff. hg - coupling hbb - coupling already at LEP Newly designed for hadron colliders

5. Johannes HallerMSSM 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,  - identification, mass resolutions...) signal efficiencies and background expectations from fast simulations 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,  - identification, mass resolutions...) signal efficiencies and background expectations from fast simulations developments/ improvements: 1)new and updated search channels: new: VBF with Higgs decay to , WW, . new: tt  bW+bH  bqq+b  updated: ttH, H  bb (better simulation of bgr.) updated/ new: bbH  H   now also had.  decay 2)improved theoretical calculations: FeynHiggs: full one-loop corrections and dominant two- loop corrections included (increase of M h by several GeV)  considered to give most accurate calculations at present developments/ improvements: 1)new and updated search channels: new: VBF with Higgs decay to , WW, . new: tt  bW+bH  bqq+b  updated: ttH, H  bb (better simulation of bgr.) updated/ new: bbH  H   now also had.  decay 2)improved theoretical calculations: FeynHiggs: full one-loop corrections and dominant two- loop corrections included (increase of M h by several GeV)  considered to give most accurate calculations at present two expected data sets: 30 fb -1 and 300 fb -1 discovery = 5  excess using Poisson statistics no systematics included two expected data sets: 30 fb -1 and 300 fb -1 discovery = 5  excess using Poisson statistics no systematics included LO SM prod. cross section (M. Spira) corrected with FeynHiggs  conservative!

6. Johannes HallerMSSM Higgs Bosons with ATLAS 6  most important channels: VBF  differences mainly due to M h almost entire (tan , M A )- plane covered  most important channels: VBF  differences mainly due to M h almost entire (tan , M A )- plane covered Light Higgs Boson (30 fb -1 ) h observable in entire parameter space and for all benchmark scenarios? ATLAS (prel.) See talk of P. Conde for SM Higgs searches with ATLAS

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

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

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

10. Johannes HallerMSSM Higgs Bosons with ATLAS 10 VBF channels, H/A   only 30fb -1 300 fb -1 Overall Discovery Potential (300 fb -1 ) ATLAS (prel.)  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 m top  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 m top ongoing:  including SUSY decay modes to increase areas for heavy Higgs bosons, e.g. H          3l + E T,miss  can SM be discriminated from extended Higgs sector by parameter determination e.g. via rate measurements? ongoing:  including SUSY decay modes to increase areas for heavy Higgs bosons, e.g. H          3l + E T,miss  can SM be discriminated from extended Higgs sector by parameter determination e.g. via rate measurements?

11. Johannes HallerMSSM 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 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

12. Johannes HallerMSSM Higgs Bosons with ATLAS 12 Back-up slides

13. Johannes HallerMSSM Higgs Bosons with ATLAS 13 SM or extended Higgs Sector ? BR(h  WW) BR(h  )  estimate of sensitivity from rate measurements in VBF channels (30 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 R = ATLAS (prel.) ATLAS (prel.)

14. Johannes HallerMSSM Higgs Bosons with ATLAS 14 Charged Higgs Bosons