1. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 1 Model ID @ 500 GeV Taikan Suehara ICEPP, The Univ. of Tokyo

2. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 2 1.Inert Higgs –WIMP:  I (scalar) –Visible:  ± (scalar) 2.SUSY –WIMP:  0 (fermion) –Visible:  ± (fermion) 3.LHT –WIMP: A H (vector) –Visible: W H ± (vector) Three models All give 2W + 2WIMP fs.

3. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 3 √s = 500 GeV, 500 fb -1 full simulation NO Initial polarization Use same masses for all the models m(visible) = 231.57 GeV, m(WIMP)=44.03 GeV Cross section is normalized (200fb & 40fb). Use W hadronic decay (cut leptonic events) Mass -> production angle calculation Full SM background included Weighted to 500fb -1 Analysis overview

4. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 4 ILD detector & framework ILD detector (ILD00) Vertex: Si pixel (3x2 layers) Silicon Tracker: 4 layers TPC(main tracker) ECAL (0.5x0.5 cm tile, Si/W) HCAL (3x3 cm tile, Sci/Fe) Solenoid (3.5Tesla) Muon detector Event generation (signal, SM background) Full-MC simulation (GEANT4) Hit, MC info(LCIO file) Event reconstruction Tracking Particle Flow Flavor tagging etc. Analysis Stdhep event files Particle information (ROOT tree) Event weighting Separation cuts Analysis (mass, angle…)

5. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 5 Signal: JSF/physsim Structure HELAS for helicity amp. calculation BASES for numerical integration SPRING for event generation –Pythia for quark fragmentation –ISR/Beamstrahlung included –~0.1 M events for each process generated Background: SLAC (ILC standard sample) –whizard/pythia for all SM processes –~14 M events in total (80-200 fb -1 for 2/4/6 fermion events, 0.1-1 fb -1 for e  /  events) Event generation

6. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 6 Selection cuts 4-jet clustering (Durham) # Track >= 20 160 < E vis < 400 GeV each E jet > 5GeV |cos  | jet < 0.99 unlike 3jet (y th,3 > 0.001) “qqqq (non-b) + missing” each jet has >= 2tracks no > 25 GeV leptons |cos  | miss < 0.9 sum |cos  | < 2.6 sum b-quark prob. < 1 kinematic fit converged 65 < m W < 95 GeV BG suppression cuts

7. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 7 Selection efficiency IH eff: 59.8%, pur (200 fb): 78.6%, pur (40 fb): 42.3% SUSY eff: 58.3%, pur (200 fb): 77.7%, pur (40 fb): 41.0% LHT eff: 58.9%, pur (200 fb): 78.2%, pur (40 fb): 41.8% Acceptable selection performance

8. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 8 W energy distribution (for mass) MC truth (signal only) Reco (kin-fitted) MC & reco have a good correlation. Difference of shapes (esp.WH) is not used for the discrimination in this analysis.

9. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 9 Mass determination Fitting: 3 rd polynomial x Voigt function (10 params) 1.All 10 params free 2.Fix 8 params (except edge positions): obtain errors of the edge positions

10. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 10 Edge positions from the fit: (MC: 96.32/174.78) Masses (MC: 231.57/44.03) Mass resolution Low edge (200 fb) High edge (200 fb) Low edge (40 fb) High edge (40 fb) IH97.00 ± 0.13 GeV 174.22 ± 0.19 GeV 97.86 ± 0.38 GeV 176.22 ± 0.84 GeV SUSY97.12 ± 0.15 GeV 173.46 ± 0.21 GeV 96.10 ± 0.54 GeV 176.02 ± 0.85 GeV LHT96.94 ± 0.16 GeV 174.39 ± 0.10 GeV 99.56 ± 0.48 GeV 174.67 ± 0.34 GeV Visible (200 fb) WIMP (200 fb) Visible (40 fb) WIMP (40 fb) IH232.28 ± 0.12 GeV (0.12) 43.41 ± 0.58 GeV (0.57) 232.40 ± 0.37 GeV (0.39) 35.42 ± 2.78 GeV (2.23) SUSY232.59 ± 0.13 GeV (0.14) 44.84 ± 0.63 GeV (0.64) 231.04 ± 0.51 GeV (0.50) 41.64 ± 2.63 GeV (2.50) LHT232.18 ± 0.13 GeV (0.13) 43.18 ± 0.52 GeV (0.50) 234.06 ± 0.35 GeV (0.41) 33.91 ± 2.07 GeV (1.56)

11. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 11 Production angle of the visible new particle can be calculated from W directions with masses of new particles and back-to-back assumption. The angle has spin info. but two-fold ambiguity (solution of 2 nd equation) exists. Production angle

12. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 12 The distribution looks reasonable. ~30% of the events cannot be used. (discriminant > 0 events selected) Discriminant distribution

13. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 13 MC & reco have reasonable correlation. Three models seem to be discriminated. 1D distribution 200fb

14. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 14 2D distribution (2 solutions) SUSY IH LHT SMBG Chi-square can be derived using these distributions.

15. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 15 Powerful for larger templates Confirmed by comparing “same” model but statistically independent samples –Uncertainty exists with finite statistics  reflects the statistical fluc. of templates between D i and T i Separation power

16. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 16 Good separation with 200 fb cross section Nearly 3  separation with 40 fb IH/SUSY has better separation –Consistent with intuitive view Separation power results Uncertainty from statistics : ~2Uncertainty from statistics : ~.3

17. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 17 Uncertainty of masses can cause uncertainty on the angular distributions We are examining such effects by simulation with shifted masses (full or generator level) Effect of mass measurement IH 40fbIH 200fb

18. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 18 With full simulation, no significant deviation can be seen between shifted and original samples (within MC statistics…) –Higher statistics with all shifted masses is not practical Generator analysis has not been finished… –Need to ‘adapt’ the MC distributions to reco ones… (with some coefficients) –Uncertainty of that adaptation should be also investigated…Results…

19. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 19 Cross section response to beam energy near the threshold reflects spin structure –SUSY has (E CM -E TH ) 0.5 response while IH/LH has (E CM -E TH ) 1.5 response. Threshold scan

20. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 20 Assume 40 fb cross section 470, 500, 530 GeV with 50 fb -1 stat. each Threshold energy is treated unknown SM bg and signal efficiency is assumed to be the same as 500 GeV Toy-MC with 3-point fittings Examine  2 of the fitting –SUSY should give low  2 for n=1/2, high  2 for n=3/2 –Opposite for IH/LH Strategy for threshold scan

21. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 21 Power of 0.5 result shows good separation between SUSY/other two models Chi-square results Power of 0.5Power of 1.5

22. Taikan Suehara, 16 th general meeting of ILC physics (Asia) wg., 2010/07/17 page 22 Analysis almost finished –Cut optimization / mass fitting –Model ID with 2d angular distribution Some work left in the mass shift analysis –Threshold scan Paper writing is ongoing (at final round?) –LCWS proceedings for both theory and 500 GeV experiment (this work) are already available –Need consistency between 500 GeV and 1 TeV workSummary/status