1. Trigger studies of SM 130 GeV Higgs  in the lepton+hadron channel First pass at estimating trigger efficiency Higgs mass reconstruction Catalin Ciobanu, Dovid Skversky, Kevin Pitts, Tony Liss Univ. of Illinois

2. Part I: Trigger Studies

3. Trigger tables – from Francesca’s talk 0 1 2 3 4 5 6 LOW-LUMHIGH-LUM Notation: 1010000 means the event fired MU20 and J200 triggers MU20(20) 2MU6 EM25I(30) 2EM15I(20) J200(290) 3J90(130) 4J65(90) J60+xE60(100+100) TAU25+xE30(60+60) MU10+EM15I

4. This will hurt efficiency Too few ATLFASTB  -jets! 10 3 10 4 10 5 10 4 10 3 10 5

5. ATLFASTB  -jets + lepton Wait! It’s even worse: 73% of events with an ATLFASTB  -jet have no leptons. Of the 536 evts that do have both a lepton and a  -jet, about 300 are below the lepton trigger. 1986/50k= 4% - very poor

6. Lepton and  -jet E T -integral spectra Investigated using one additional trigger: Lepton +  -jet. 3 variables: –Lepton E T –  -ID flag (ATLFASTB! Remember small efficiency) –  -jet E T

7. Default Efficiency Using Erik’s parametrization for the jets –Not for the  jets –For the  triggers use ATLFASTB info, not the ‘truth’ –Given N (N  7) choose the most efficient N triggers: Low luminosity regime: N= 1: 0000010 0.13598000 (jet+MET) N= 2: 1000010 0.24079999 (+muon) N= 3: 1100010 0.32436001 (+electron) N= 4: 1100011 0.33831999 (+taujet+MET) N= 5: 1110011 0.34233999 (+1jet) N= 6: 1111011 0.34255999 (+3jet) N= 7: 1111111 0.34268001 (+4jet) High luminosity regime: N = 1 1000000 0.12954000 (muon) N = 2 1100000 0.21585999 (+electron) N = 3 1100010 0.24330001 (+jet+MET) N = 4 1100011 0.24548000 (+taujet+MET) N = 5 1110011 0.24738000 (+1jet) N = 6 1111011 0.24745999 (+3jet) N = 7 1111111 0.24745999 (+4jet)

8. Adding  +lepton trigger LOLUM Max. increase: 0.5%= (34.4-34.3)/34.3 Max. increase: 2.1% = (25.3 - 24.7)/24.7 Plot: 100* [ eff (1111111 1 )-eff (1111111 0 )] / eff (1111111 0 )

9. “Perfect”  -jet identification Max. increase: 6.1%Max. increase: 33.5% = (38.1-28.6)/28.6 Plot: 100* [ eff (1111111 1 )-eff (1111111 0 )] / eff (1111111 0 )

10. Imperfect  -jet identification Plot: 100* [ eff (1111111 1 )-eff (1111111 0 )] / eff (1111111 0 ) as  -ID efficiency is varied from 10% to 100%. E T (lep)>5GeV E T (  -jet)>5GeV perfect ID ATLFB

11. Conclusions Rough pass at trigger efficiencies for H  in the lepton+hadron channel Backgrounds? –Top pair production –Bottom pair production –W/Z+jets production –Z  Some (all?) exist; some may have to be generated Study improvements to S/B –Cut on  between lepton and  -jet

12. Part II: Higgs Reconstruction For this study, to improve statistics, we use the ATLFAST(not-*ATLFASTB*)  -jets, i.e. the ‘truth’  -ID: abs(KFJET[i])=15

13. Collinear Approximation  Assume the neutrinos ( 1 + 2 ) that go with the lepton move along the same transverse direction as the lepton itself (no need to assume same  as well)  Similar for the  -jet and the other neutrino 3.  Conserve energy and momentum –Missing energy = transverse comp. of 1 + 2 + 3 –Solve for the transverse comp. of ( 1 + 2 ) and 3. –Solve for the longitudinal comp.: If complex solutions, then also assume the same  (fully collinear approximation). This means giving up the P z mom. conservation in 21% of the events e,  1 + 2  -jet 3 Transverse plane

14. Leptonic and hadronic  reconstruction Needs debugging

15. Higgs Mass Reconstruction 4.3% events have M H >300

16. More Higgs plots Collinear approximation gets better as momentum increases:

17. Conclusions II We got a mass peak! –There may be room for improvement? Fit in the 110-150 range: 131.9  9.8 GeV Clean up the bugs New ideas for complex Pz solution cases?