1. Impact of ILC Tracker Design on e  e   H 0 Z 0       X Analysis Hai-Jun Yang & Keith Riles University of Michigan, Ann Arbor SiD Benchmarking Meeting December 19, 2006

2. 12/19/2006H.J. Yang - SiD Meeting2 Physics Motivation  To determine the suitable ILC SiD tracker momentum resolution which is capable to make direct measurement of e  e   H 0 Z 0      X –Based on ILC500 beam setup –Polarization of e  is -85%, e  is 0 –PandoraV2.3 (modified for H      decay, thanks to Michael E. Peskin) and PythiaV3.3 –Java Analysis Studio V2.2.5 –SDMar01, Fast MC Simulation and 1000 fb -1

3. 12/19/2006H.J. Yang - SiD Meeting3 Cross Section of HZ       X

4. 12/19/2006H.J. Yang - SiD Meeting4 Monte Carlo Samples Signal – 10K – e  e   H 0 Z 0       X – Cross section is 0.018278 fb for M H =120 GeV – 18 signal events expected for 1000 fb -1 Background W + W       – 400 K – Cross section is 149.68 fb –149680 WW events expected for 1000 fb -1 Background Z 0 Z 0      X – 100 K – Cross section is 31.6 fb – 31600 ZZ events expected for 1000 fb -1

5. 12/19/2006H.J. Yang - SiD Meeting5 Preselection Cuts “Good”  –a) P  > 20 GeV –b) |cos   | < 0.8 At least 2 “Good”  For | M  – 120 | < 5 GeV –Signal 10K  6442 Eff_signal = 64.42% –Bkgd ZZ 100K  382 Eff_zz = 0.382% –Bkgd WW 400K  1019 Eff_ww = 0.25475%

6. 12/19/2006H.J. Yang - SiD Meeting6 Additional Selection Cuts H   : 10K  6442  5959  5780  10.57 (exp) ZZ Bkgd: 100K  382  164  141  44.8 (exp) WW Bkgd:400K  1019  135  47  17.6 (exp) Angle between two  Polar angle of two 

7. 12/19/2006H.J. Yang - SiD Meeting7 M  vs Track Momentum Resolution

8. 12/19/2006H.J. Yang - SiD Meeting8 Signal Events - Detection Significance Rescaling factor of  (1/pt) |M  -120|<0.2 (GeV) N bkgd = 2.4, N s N s /  N bkgd (Significance) |M  -120|<0.1 (GeV) N bkgd = 1.2, N s N s /  N bkgd (Significance) 1.06.34.13.353.1 0.509.56.16.25.7 0.2510.56.89.58.7 0.1510.56.810.49.5 0.1010.56.810.59.6 0.0510.56.810.59.6  The H   significance is improved with better track resolution.

9. 12/19/2006H.J. Yang - SiD Meeting9 Branching Ratio Uncertainty Rescaling factor of  (1/pt) |M  -120|<0.2 (GeV) N bkgd = 2.4, N s  (N s +N bkgd )/ N s (Uncertainty) |M  -120|<0.1 (GeV) N bkgd = 1.2, N s  (N s +N bkgd )/N s (Uncertainty) 1.06.346.7%3.3563.7% 0.509.536.0%6.243.9% 0.2510.534.0%9.534.4% 0.1510.534.0%10.432.7% 0.1010.534.0%10.532.6% 0.0510.534.0%10.532.6%  With the SiD’s nominal momentum resolution, one can measure Br(H   ) to 47%. The precision improves only modestly with improved track resolution.

10. 12/19/2006H.J. Yang - SiD Meeting10 Higgs Mass Resolution & Accuracy Rescaling factor of  (1/pt) Mass resolution (MeV) Mass Accuracy (GeV)  2 / n.d.f 1.0239.6 ± 140.9120.0 ± 0.090.10 / 67 0.50117.6 ± 63.3120.0 ± 0.120.065 / 37 0.2559.9 ± 16.3120.0 ± 0.090.046 / 27 0.1536.6 ± 9.5120.0 ± 0.090.044 / 17 0.1025.4 ± 6.4120.0 ± 0.090.074 / 15 0.0513.8 ± 3.6120.0 ± 0.10.022 / 5  Better Higgs mass resolution with better track resolution.

11. 12/19/2006H.J. Yang - SiD Meeting11 Fit M  Distributions

12. 12/19/2006H.J. Yang - SiD Meeting12 Fit M  Distributions

13. 12/19/2006H.J. Yang - SiD Meeting13 Fit M  Distributions

14. 12/19/2006H.J. Yang - SiD Meeting14 Preliminary Conclusions  With the SiD’s nominal track momentum resolution, one can establish detection of H   with 4-sigma significance and can measure Br(H   ) to 47%.  The detection significance improves significantly with improved track momentum resolution, but branching ratio of H   improves only modestly.