1. Frascati – 20.06.2008 D. Cavalli 1  detector requirements  very short reminder of MSSM Higgs sector  very short reminder of EtMiss and Tau performance  short summary of CSC HG7 results  what we have learnt from CSC exercise  first data:  validate EtMiss and Tau reconstruction  study Z    future plans for A   study  some first ideas for Analysis model MSSM Higgs H/A  

2. Frascati – 20.06.2008 D. Cavalli 2  EtMiss resolution/linearity (  mass reconstruction) and Tau Identification (background rejection) are crucial points for this channel  Milano strongly involved in the EtMiss and Tau reconstruction in ATLAS since the beginning (responsible of MissingET package for EtMiss recontruction/calibration)  b-tagging efficiency is also important: H/A are mainly produced in association with bb (Roma1 studies on b-tagging)  Study of Z   with the first data very well advanced reported in CSC EtMiss and Tau Notes  to validate EtMiss and Taus  to determine in situ the EtMiss and Tau-jet scale ……to be ready for the A/H  analysis see my talk yesterday Detector requirements for the study of Higgs  

3. Frascati – 20.06.2008 D. Cavalli 3 MSSM 2 Higgs doublets, 5 Higgs bosons: h, H, A, H+, H- Parameters in benchmark scenarios fixed, here: m h max scenario Properties depend on two free parameters: tan  = v1/v2 (v1, v2 vacuum expectation values), mA Higgs produced directly via gg fusion or in association with b-quarks MSSM Higgs sector Enhanced Higgs coupling to b quarks:  bbA ~tan 2  Mass degeneration of at least 2 bosons single cross sections added up At high tan , A and H couple dominantly to the heaviest lepton and to the heaviest down-type quark: BR(bb)=90%, BR(  )=10%

4. Frascati – 20.06.2008 D. Cavalli 4 EtMiss performance Resolution = σ ( MET (Rec)- MET (truth) ~ in low and medium regions of SumEt –Displacement at very high regions (high pt jets) and very low regions (noise suppression method) Linearity = (MET (truth)- MET (Rec))/MET (truth) within 5% Angular resolution (100 mrad for EtMiss> ~ 80 GeV) Dependence on the event topology The reconstructed m  is dominated by EtMiss measurement: EtMiss linearity and resolution are crucial for m  reconstruction

5. Frascati – 20.06.2008 D. Cavalli 5 Tau performance In rel. 14 merge Tau collections from Calo-seeded and Track-seeded reconstruction. Likelihood (built from calo and inner quantities) for Identification. Electron, muon veto implemented Mean= -0.5% Sigma= 7.3% Mean=-1.0% Sigma=9.7% The Tau-Identification/jet rejection is crucial to suppress backgrounds.

6. Frascati – 20.06.2008 D. Cavalli 6 Collinearity hypothesis Generated m Z p.l. reconstructed m  ETMiss calc from particles in |  |<5) reconstructed ETMiss Effect of detector acceptance Effect of EtMiss reconstruction  (m  )  ETmiss |sin (  )| Z  Invariant  mass reconstruction All reco quantities A(450)  m  can be reconstructed in the collinear approximation

7. Frascati – 20.06.2008 D. Cavalli 7  Study the three different final decay modes: Lepton-lepton (BR=6.3%) Lower rate, less favourable kinematic, low mass region Lepton-hadron (BR=46%) All mass regions Hadron-Hadron (BR=41%) Possible in high mass region (huge QCD background)  Different trigger issues  Similar analyses  Inclusive analysis: do not use b-tagging  do not separate events from direct and associated production  Exclusive analysis: different analysis for direct and associated production. Can combine at the end. A/H   channel: final states In CSC note the more advanced one: lepton-lepton channel  reasonable background statistics available, complete study of systematics

8. Frascati – 20.06.2008 D. Cavalli 8  Main backgrounds : tt, Z  ll, Z   estimate shape and normalisation of Z   background from Z   data  Selection: A/H    lepton-lepton At least one b-tag required, no contributions from gg fusion All lepton-lepton final states considered Analysis performed for masses between 110 GeV and 200 GeV integrated luminosity: 30 fb -1 Different cuts for ee/  and e  channel, due to different background compositions  Exclusive Analysis

9. Frascati – 20.06.2008 D. Cavalli 9 A/H    lepton-lepton (2) The lepton-lepton channel is less sensitive than the lepton-hadron channel Systematic errors included (jet & EtMiss scale uncertainty dominates ) Exclusive Analysis

10. Frascati – 20.06.2008 D. Cavalli 10 A/H    lepton-lepton (3) To be done in first data Mass range: 130-200 GeV Integrated luminosity 1fb -1 Z   background estimated from data Inclusive Analysis

11. Frascati – 20.06.2008 D. Cavalli 11 5-  discovery contour in (M A, tan  ) plane from ATLFAST with 30 fb -1 for : A°/H°    lep-had ( BR=46%) (ATL-COM-PHYS-2003-009, by D. Cavalli, G. Negri) A°/H°    had-had ( BR=41%) (ATL-PHYS-2003-003, by J. Thomas) :  contribution to discovery potential for M A > 450 GeV (blue curve) combined (lep-had + had-had) Atlfast Discovery potential of A/H    lepton-hadron in ATLAS already sudied in TDR (full simualtion) and with fast simulation (very large bakground statistics). A/H    lepton-hadron

12. Frascati – 20.06.2008 D. Cavalli 12 Backgrounds : irreducible : t t  WW  lep -   lep-had, Z/   (Z+jets)    lep-had reducible : t t  WW  lep - had, W+jets  lep + jets, bb  lep-had Selection:  Criteria used for fast Analysis + criteria studied for Z   analysis kinematical +  -Id + mass (OS and SS events separation) A/H    lepton-hadron (2)  For m(A 0 ) < 450  associated bbA and direct A production important: two uncorrelated analyses for direct and associated processes: Direct production analysis : no b-tagged jets with p T > 15 GeV, |  | < 2.5 (against bb and tt) Associated production analysis :  1 b-tagged jet (pT b-jet Max60 GeV, pT 3° jet40GeV) both analysis on both signals and backgrounds: significances combined to get final results  For m(A 0 )  450 associated bbA production completely dominant: only associated analysis  Exclusive Analysis against tt (dominant backgd)

13. Frascati – 20.06.2008 D. Cavalli 13 mA=300GeV tt W+jets J5 A/H    lepton-hadron (3) Low statistics for backgrounds evaluation (large errors) Not enough statistics for backgds for complete evaluation of systematics No systematics errors  Exclusive Analysis : CSC data

14. Frascati – 20.06.2008 D. Cavalli 14 mA=150GeV Compare reconstructed m  NO-pileup Pileup Mean =151  =25 Mean =159  =30 A/H    lepton-hadron: effect of pileup m  : displaced peak/worse resolution  work on pileup suppression Main effect from pileup on  -jet Identification  need to change cuts on Likelihood/Likelihood

15. Frascati – 20.06.2008 D. Cavalli 15 Need a lot of background events (many severe cuts, high thresholds, two exclusive analyses…) –Impossible to have all them in full simulation –Use Atlfast I or Atlfast II Participating to the effort of AtlfastII validation Try to estimate tt background (the dominant one) from data Need a careful evaluation of systematics errors –Large statistics needed to be sensitive Evaluate the real gain using the two exclusive analyses What can we do with <30fb -1 ? Exclusion limits? 10 TeV? What we have learnt from CSC experience

16. Frascati – 20.06.2008 D. Cavalli 16 A lot of work to do with first data to validate EtMiss and Tau  work in close connection with Calorimeters Data Preparation/Data Quality  many SM events with EtMiss and Tau signature  Z  very useful to  check the detector  understand in situ the performance of algorithms set up with the simulated data  determine the absolute energy scale of EtMiss and Tau  study in situ Tau-Identification efficiency  …also interesting physics study … The analysis set up for the Z   study can be applied for H   search Conclusions/work to be done with first data

17. Frascati – 20.06.2008 D. Cavalli 17 First realistic test of the analysis model and tools from the FDR2 exercise: Primary DPDs (pool.root) Tertiary DPDs (root ntuple) Secondary DPDs (pool.root) ESD/AOD (pool.root) TauDPDMaker ARana Standard Reco Analysis  Final plots (histo.root) and numbers Analysis model

18. Frascati – 20.06.2008 D. Cavalli 18 1.Send Ganga jobs to the 4 IT T2 to run TauDPDMaker on input AODs to produce output DPD1 2.Store output DPD1 on MI SE 3.Send ARana jobs via Grid to the Mi T2 or run it locally to produce output plots/numbers RB CE SE WN MI-T2 NA- T2 RO –T2 LNF- T2 WN 1 1 1 1 3 3 3 3 2 2 2 RB=resource broker CE=computing element SE=storage element WN=worker node Analysis model First realistic test of the analysis model and tools from the FDR2 exercise

19. Frascati – 20.06.2008 D. Cavalli 19 Backup slides

20. Frascati – 20.06.2008 D. Cavalli 20  J. Schaarschmidt, M. Kobel, W. Mader (Dresden) (lepton-lepton)  E. Barberio, M. Bischofberger (Melbourne), A. Saavedra (Sydney) (hadron-hadron)  D. Cavalli, S. Resconi, C. Tamarindi (Milano), W. Davey (Milano/Melbourne) (lepton-hadron)  E. Gross, O. Silbert (Weizmann) (lepton-lepton)  E. Kuznetsova, S. Gentile (Roma1) (lepton-lepton)  T. Vickey (Wisconsin) (lepton-lepton)  J. Lu (Alberta) (hadron-hadron) People involved

21. Frascati – 20.06.2008 D. Cavalli 21 E lept,E  -jet = energy of t visible decay products j  = angle between directions of visible decay products E 1, E 2 = energy of the 2 neutrino systems m  =  2(E lept + E 1 )(E  - jet + E 2 )(1 - cos  ) Energies of two neutrino systems calculated by: E x = (E 1 * u 1 ) x + (E 2 * u 2 ) x E y = (E 1 * u 1 ) y + (E 2 * u 2 ) y The determinant of system has to be not zero (sin  ≠0) lepton and  -jet not back-to-back E 1, E 2 have to be > 0  Collinear approximation: direction of the neutrino systems are the ones of the visible decay products(u 1,u 2 )  m  = 0 this system can have no good solutions  the invariant mass cannot be always reconstructed Invariant  mass reconstruction