1. L. Perera LPC physics meeting 11/17/2005 1 Search for H/A →  Lalith Perera Rutgers University for Rutgers CMS Group Amit Lath, Keith Rose, Sunil Somalvar, Steve Schnetzer, Bob Stone, Alik McPerson, Dimity Hits, (Eva Halkiadakis)

2. L. Perera LPC physics meeting 11/17/2005 2 Why H→  At LHC MSSM higgs are expected to produced by gg →bbH, gg →H qq→ H Dominant decay modes of H: B(H→  ) ~ 8%, B(H→ bb) ~90% bb channel is affected by large dijet background could tag associative b to lower backgrounds Dominant back ground to  from Z/  *: can be estimated ( # of Zs from Z→e e,..)   channel could be equally promising

3. L. Perera LPC physics meeting 11/17/2005 3  →e   →e 3 High DY → ee BG  →    →  3 High DY →  BG  →e   →  6 low QCD BG  →e   →h 23 promising  →    →h 23 promising  →h   →h 41 multi jet BG modefraction %comments H→  Decay Modes

4. L. Perera LPC physics meeting 11/17/2005 4 CDF results on H   Rutgers CDF group did CDF run II, H   analysis

5. L. Perera LPC physics meeting 11/17/2005 5 B/  group (and others) already working on this channel Rutgers group plan to concentrate on low mass higgs low mass higgs search is challenging due to overlap with Z

6. L. Perera LPC physics meeting 11/17/2005 6 CMS hadronic taus Level 1: narrow hadronic jet with E T cut Level2 (HLT): Localized energy in ECAL – isolation 0.4 Level 25: isolation in tracker (Calo+pixel, Si) signal cone 0.07, isolation cone, 0.4, E T, P T Offline taged tau jets: Isolation using fully reconstructed tracks

7. L. Perera LPC physics meeting 11/17/2005 7 1 tau jet E T > 93 GeV (104 high L) 2 tau jets E T > 66 GeV (76 high L) …. This is good at rejecting Z back ground 22 11 E T of  from Z →  GeV L1 tau trigger:

8. L. Perera LPC physics meeting 11/17/2005 8 But also rejects low mass higgs M(H) = 120GeVM(H)= 140GeV 22 11 22 11  ET

9. L. Perera LPC physics meeting 11/17/2005 9 L1 efficiency for H→  1 or 2 tau bit L1 global efficiencyAny L1 tau bit Any: tau 1, tau 2, tau+gamma

10. L. Perera LPC physics meeting 11/17/2005 10 L1 Trigger rates DataL1 Accept1 or 2 Tau“Any” Tau Z->ee 16.8%0.2%8.0% Z->  55.8%0.9%3.7% Z->  65.9%0.1%3.0% H(120)->  38.1%0.8%11% H(140)->  44.0%1.0%15% H(180)->  53.2%2.8%25% H(250)->  67.7%15%41%

11. L. Perera LPC physics meeting 11/17/2005 11 Possible ways to improve sensitivity to low mass higgs Understanding/estimating back grounds Tau reconstruction: to reject jet backgrounds, improve energy resolution Use tau Impact parameter Any other signatures of   →  –angular distributions. H scaler, Z-vector

12. L. Perera LPC physics meeting 11/17/2005 12 Number of tracks in tagged tau jets. (from H→  m(H) =140) (fewer 3 prong taus likely a bug in Exroot) Tau mass reconstruction  → h  0 25.9%  →h 11.8%  → 3 h 10%  →h 2  0 9.4%  → h3  0 4.5%

13. L. Perera LPC physics meeting 11/17/2005 13 Tau mass Calculation Case study with 140GeV  →  Use tau tagged jets with a single track (  →  n  0 ) Add energy in ECAL and HCAL cells within 0.25 of jet axis exclude cells 0.04 (ECAL)/0.15 (HCAL) from track Calculate the momentum of photons and take the sum Add track momentum and energy Calculate invariant mass

14. L. Perera LPC physics meeting 11/17/2005 14 Angle between pion and gammas in the tau decay (from MC)

15. L. Perera LPC physics meeting 11/17/2005 15 Visible tau mass from generator e/p of tau decay particles except neutrinos. (what is possible with an ideal detector ) Reconstructed Tagged tau jet Invariant mass (for single track tau jets)

16. L. Perera LPC physics meeting 11/17/2005 16 Improving tau mass reconstruction Is it track energy In ECAL MIP or more? Can we identify?       Opposite form what is expected ?  CAL  CAL

17. L. Perera LPC physics meeting 11/17/2005 17 fraction of energy in HCAL, f <0.05 f > 0.05 Again, does not look right ? Investigating! Reconstructed visible tau mass single track tau jets

18. L. Perera LPC physics meeting 11/17/2005 18 Reconstructing higgs mass Calculate  energy, momentum in collinear approx. add to to the visible e-p to get mass. Method used by CERN (Higgs PRS) group:

19. L. Perera LPC physics meeting 11/17/2005 19 H/A mass generator level Reconstructed 2  mass from MC parameters of t decay products Use energies of s to get E T Use e-p of tau decay particles as jet/track energy A 30% minimum loss for 140 GeV H Testing Collinear approximation  

20. L. Perera LPC physics meeting 11/17/2005 20 Alternate method ( CDF ) Use missing E T (Ex, Ey) from calorimeter and Take neutrino E =E T Px=Ex; Py=Ey; Pz= 0 GeV For m(H)=140 GeV Generater level p-E from tau decays particles E T from neutrinos No loss of efficiency, Lower reconstructed mass

21. L. Perera LPC physics meeting 11/17/2005 21 Future Plans More trigger and background studies (more MC) Improvements to tau mass reconstruction Looking at other possible parameters, …

22. L. Perera LPC physics meeting 11/17/2005 22 Back up slides

23. L. Perera LPC physics meeting 11/17/2005 23

24. L. Perera LPC physics meeting 11/17/2005 24