1. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 1 SUSY and Tau-pair analysis with full simulation in ILD detector model Taikan Suehara ICEPP, The Univ. of Tokyo

2. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 2 Benchmark processes: Physics process for optimization Processes (e + e -  ) √S (GeV) ObservablesComments ZH, ZH  e + e - X,250 , m H m H =120GeV, test materials and  ID      X250 , m H m H =120GeV, test  P/P ZH, H  cc, Z  250Br(H  cc)Test heavy flavour tagging and anti- tagging of light quarks and gluon, Z  qq250Br(H  qq)Same as above in multi-jet env. Z*      500  A FB, Pol(  Test  0 reconstruction and  rec. aspects of PFA tt, t  bW, W  qq’500  A FB, m top Test b-tagging and PFA in multi-jet events. m top =175GeV           500  m  Point 5 of Table 1 of BP report. W/Z separation by PFA

3. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 3 Tau-pair

4. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 4 Motivation of tau-pair study Detector challenge: –A few particles in very narrow angle (  =140) Esp.  0 reconstruction from 2  s Physics motivation: –Anomalous coupling with Z’ Cross section Angular distribution (A FB ) –Charge ID is easy (cf. jet) Polarization –Angular distribution of decay daughters

5. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 5 1.Number of track <= 6 –Veto hadronic events 2.Specialized jet clustering (TaJet) –Customized to taus (several particles within narrow angle) –1 positive & 1 negative jets required for further analyses 3.Opening angle > 178deg –Suppress WW to l l  background 4.40 < E vis < 450 GeV –  ->  and Bhabha rejection 5.2-electron and 2-muon veto –For bhabha and ee->  veto –E-ID by Ecal/total deposit,  -ID by hit/track energy 6.|cos  | < 0.9 for both jets –Bhabha is completely suppressed by this cut BG suppression cuts

6. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 6 Result of SM suppression cut Preliminary: luminosity not normalized,  not contained. AllTau #tr cut only 11085 78 69489 Angle cut 13949 9 19504 Evis cut 2658918996 ee,  cut 1940317378 cos  cut 1528414808 Remaining bhabha is 0 in 0.1 fb -1 -> Bhabha background is < 10% of signal (Need more events for precise estimation)

7. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 7 # of bg events is much smaller than signal events –If we precisely estimate bg amount, statistical error of signal only concerns to  and A FB measurements Effective cross section after cut is 490 fb (21.3% acceptance) –Corresponds to 0.2 % error in  and 0.28% error in A FB at 500 fb -1 Forward-backward asymmetry SM calculation (Red: left, Blue: right)

8. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 8 Decay modes in A pol analysis Branching ratio: 17.8% 3 body decay; pol. info is smeared  -> e Branching ratio: 17.4% 3 body decay; same as e mode  ->  Branching ratio: 10.9% Pol. can be directly observed by  distribution  ->  Branching ratio: 25.2% Pol. of  can also be obtained by  distribution in  -rest frame (pol. of  is connected to pol. of  )  ->  ->  Branching ratio: 9.3% Currently not used because statistics is low  -> a1  a1  -> 

9. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 9 A pol calculation (  mode) Stat error in 500fb -1 Value shift due to the mode BG Values obtained by signal-only events!

10. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 10 Clear difference observed in invariant mass distributions. –LDC’s best, larger is better in Jupiter geometries. –Mark confirmed the granularity affects the mass distributions. Three candidates in  mode selection –No  0 mass cut,  0 cut with left edge included / excluded  and  0 reconstruction

11. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 11 A pol calculation (  mode) Stat error in 500fb -1 Value shift due to the mode BG Values obtained by signal-only events!

12. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 12 Tau-pair Summary Tau-pair events are analyzed in ILD framework. SM background can be efficiently removed by appropriate cuts. –Bhabha statistics is short -> need pre-selection –No  events –Weighting of background is needed -> All will be performed in ILD reference detector for LOI A pol analysis is implemented, showing larger and highly granulated detectors give better performance. Up to 5 TeV Z’ boson can be measured by measuring anomaly to the tau-pair production.

13. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 13 SUSY

14. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 14 Qqbar 4jet events, 130(chargino),30(neutralino) fb 500 fb-1 with full simulation Chargino/neutralino must be separated by identifying daughter W/Z. Main BG: SM WW -> 4 jets (10000 fb), aa_WW etc. SUSY jet mode

15. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 15 # of tracks > 20 –Remove leptonic events 150 GeV < Evis < 300 GeV –Remove 2-photon and qq/qqqq events Maximum lepton energy: < 20 GeV –Remove semileptonic events All jet > 5 GeV –Remove 2-jet / misclustering events |cos(  )| < 0.9 for all jets –Remove t-channel events (sneutrino is heavy in point5) All jets have at least 2 tracks –Remove taus Missing Pt > 10 GeV –Remove 2-photon, WW events SM Rejection cuts

16. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 16 SM background rejection SM background is well suppressed. (need more aa_qqqq events) LDC’

17. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 17 Di-jet mass distribution All combination, reco, point5

18. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 18 Di-jet mass SM background No specific structure, I don’t include it now (need more stat.)

19. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 19 Fitting ch1/ne2 combined Chi-square/NDF is around1, not so bad. (Fitting range is restricted, fit is single-2dgaus each for W/Z with pol1 bg, 8 params)

20. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 20 Chargino amount: 52.8 +/- 1.06 (2.0%) Neutralino amount: 7.57 +/- 0.46 (6.1%) –All 8 parameters are float. –Not normalized to cross section. –Neutralino is not so good. Chargino/neutralino is different by about 20% (less neutralino) –Acceptance by SM rejection cut might be different – need to be checked Stat. error (preliminary)

21. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 21  2 distribution / mass cut

22. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 22 SUSY mass is determined by kinematics –Daughter W/Zs have characteristic energy distribution Fitting function: –For neutralino: erf(left) x erfc(right) –For chargino: erf(left), conbolution of linear and erfc for right Generator-level energy distributions (by Akiya): Mass fit of chargino/neutralino Chargino (W) Neutralino (Z)

23. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 23 Chargino mass fit MC cut and nocut shape is almost the same (wo left edge). No significant difference between geometries can be seen.

24. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 24 Fitting function: 3 rd polynomial (4 param) (center) / 0 (edge) convoluted with a Gaussian with  as linear function of energy (2 param) edge position: 2 param, total # of parameters = 8 Cheat fitting: 1. fix edge positions at true value, fit other 6 parameters. 2. fix those 6 parameters and fit edge positions. No significant difference between geometries. Chargino mass fit results

25. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 25 Neutralino mass fit Distribution in LDC is slightly broader (worse resolution). Chargino background might not be negligible for lower edge.

26. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 26 Fitting function: Error function (left) x Complementary error function (right) Width of left and right is the same, # of parameters = 4 Cheat fitting: Same as chargino J4LDC gives slightly larger width than other two. Corresponding fitting error is enhanced. Neutralino mass fit results

27. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 27 Angular distribution W decay angle Chargino production angle Detailed analysis is to be done.

28. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 28 SUSY benchmark is ongoing Cross section is obtained from 2d W/Z mass spectrum W/Z mass separation is feasible Preliminary mass fit result is obtained SUSY summary

29. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 29 Short comments on Jet Clustering

30. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 30 Motivation of new jet clustering Most of important physics processes have multi-jet final states (usually with number of heavy flavor jets) –ZHH: 6 jets with 4 b-jets Cross section of Z to ll and nn mode is too small (~0.06fb), analysis of 6-jet final states (~0.13fb) is inevitable. ttbar background (~1pb) is very severe. 4 b-tagging with high tagging/anti-tagging efficiency is necessary. –ttH: 6-8 jets with 4 b-jets –tt: (mostly as background) 6 jets with 2 b-jets

31. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 31Sample IP Traditional jet clustering (not using vertex info)

32. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 32Sample IP Off-vertex tracks Jet clustering with Vertex info Finding a secondary vertex Finding jet-coresAssociate fragments

33. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 33 Modified ZVTOP sample

34. Taikan Suehara, ILC physics mini-workshop, 2009/01/21 page 34 ZVTOP – done well with slight modification –Large-angle particles are missing? – need check Clustering algorithm using vertices –Implemented – might be not so bad –Without vertex, performance is almost the same as traditional Durham method Angular distribution of reconstructed jets –Slightly worse in new clustering Might be due to mis-vertexing (about 1/5-10 events) Flavor tagging performance – now checking –Can be done within ~2 weeksPerformance/Comments