1. Higgs Physics with ATLAS Arno Straessner Journée de réflexion du DPNC 14 septembre 2007

2. 2 60 Secs Commercial Break Δχ 2 M H /GeV theory experiment λHλH V(Φ H )...soon at the LHC

3. 3 Standard Model Higgs - Production and Decay

4. 4 Search Channels the easiest: H→ZZ →4ℓ the low-mass signal: H→γγ 10 fb -1 four high p T leptons and Z mass constraint 1% mass resolution background from sidebands

5. 5 Search Channels in the most promising mass range: VBF qq → V*V*qq → Hqq → WWqq / ττqq forward jet tagging central jet veto → reduced background 30 fb -1 1 fb -1 10% mass resolution

6. 6 SM Higgs Mass Reach at LHC careful with NLO corrections to gg→H → reduced significance most interesting mass range → many channels to combine!

7. 7 Strategy for First Data background and reconstruction studies → discovery!

8. 8 Higgs Spin and CP in SM: Higgs is 0 ++ measure spin and CP in H decay easiest in H→ZZ →4ℓ mass of off-shell Z

9. 9 Higgs Spin and CP ZZ decay plane correlations for 100 fb -1 with complete detector simulation decay plane angle + fermion angle in Z rest frame CP+ CP-

10. 10 Higgs Spin and CP measurement of H→ZZ couplings spin-0 case: SM CP+ CP- A Re(C)

11. 11 Summary and Outlook quick overview of SM Higgs search 5 sigma significance possible with 10 fb -1 over wide mass range (M H >130 GeV) low mass region needs more luminosity: ~ factor 2-3 spin and CP structure can be determined in H→ZZ (and also in VBF) some more data will be needed in the meantime: –try to prepare analysis as realistic as possible –refine search methods –new statistical procedures (beyond LEP) we will find the Higgs – if it’s there...

12. 12 Higgs Spin and CP possible in VBF Spin 0 CP +1 non-SM coupling in ZZ → H Δφ of tag jets