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17th General Meeting of the ILC Physics Subgroup Meeting
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Oct. 9 (Sat) at Room 425, Building 3, KEK
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0) Attendants:

H.Ono (NDU)
T.Saito (Tohoku)
M.Asano (Tohoku)
E.Kato (Tohoku)
Y.Okada (KEK)
D.Harada (KEK)
Y.Kiyo (KEK)
R.Yonamine (Sokendai)
Y.Yamamoto (Sokendai)
P.Posch (Sokendai)
S.Matsumoto (IPMU)
T.Suehara (Tokyo)
T.Tanabe (Tokyo)
S.Kawada (Hiroshima)
K.Fujii (KEK)

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Opening Comments
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Reports from Subgroups
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[A] Symmetry breaking & mass generation
1) ZH subgroup
1-1) xxH analysis (Reported by H.Ono)
Status:

- Setup: mh=120GeV, 250fb^-1@250GeV, Pol(e+,e-)=(+30%,-80%)

Generator: whizard
Analysis framework: ilcsoft v01-06
RDR (LOI 250GeV), SB2009 w/TF (350GeV)
- Changes since the last time
H->WW/gg separated from the other modes
350GeV analyses
Next Step:
- Binning dependence has been improved but there is still some problem remaining.
- Publication as soon as this binning dependence problem will have been solved
- New benchmark processes.

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2) ZHH Subgroup (Reported by K.Fujii on behalf of Junping)
Status:
- llHH: 3.6 sigma, qqHH: 2.0 sigma (full simulation)
- nunuHH: 1.3 sigma (w/o ZZH BG)
-> combined significance: 5.1 sigma with 2ab^-1
Next Step:
- ZZH BG for nunuHH analysis

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3) TTH Subgroup (Reported by R.Yonamine)
Status:
- Signal(tth): 0.45fb w/NRQCD correction (no beam pol.)
- BG: ttg(g->bb), ttZ(Z->bb), tt(reducible but large)
- NRQCD correction to ttH, ttZ
- Analysis: being finished.
- Sensitivity to the Yukawa coupling (delta gt/gt)
--> no pol: 11.4% (4.4sigma) with 1ab^-1
(-0.8,+0.3): 8.8% (5.7sigma)
Nest Step:
- Publish the results.
- Move on to full simulation

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4) AA->HH Group
4-1) Theory (Reported by Harada)
Status:
- Paper submitted to PRD
Next Step:
- HHH coupling
Optimum energy for e+e- -> ZHH, nunuHH?
-> IWLC2010

4-2) Experiment (Reported by Kawada)
Status:
- AA->HH:16ev/yr (signal), WW:15Mev/yr, ZZ:12kev/yr (BG)
- NN training
-> 10^-7 WW-rejection achieved
-> 2x10^-3 ZZ-rejection
-> 1.6-sigma
--> cheated jet clustering: ZZ-rejection becomes 8.5x10^-5
--> 5.9-sigma
- 4b BG: 960fb (w/o cuts)
-> Under investigation
Next step:
- Further NN-training
- Improve b-tagging & jet-clustering
- Heavier Higgs
- 4b BG
- Write a paper.

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[B] New physics
1) Model Discrimination
1-1) @ 1000 GeV with 500fb^-1 (I) (Reported by T.Saito)
3 generic cases to be discriminated:
a) J=0: Inert H-like model
b) J=1/2: SUSY-like case
c) J=1: LHT-like case
- Added new BG: ZZ and ZH
- Looked at E_W
- Event selection study using full simulation (signal and BG) samples
--> Performance good enough for the E_W end-point study.
- Mass determination
delta M_X/M_X = O(0.4%(1%)) for 200(40)fb
delta M_DM/M_DM = O(2%(8%)) for 200(40)fb
- Angular distribution
-> clear model separation possible with 200fb^-1 using chi2/ndf
calculated as the deviation from templates
--> studying the effect of mass measurement
- Threshold scan
--> 3-point fit to sigma(rs,n) = a(s-4m^2)^n with n=1/2, 3/2
@ rs=750, 775, 800 GeV with 50fb^-1 each assuming sigma=40(200)fb
--> no resolving power for 40fb.
--> useful to separate SUSY.
Next Step:
- Write a paper

1-2) @ 500 GeV (I) (Reported by T.Suehara)
3 generic cases to be discriminated:
- Mass determination
delta M_X = O(0.1(0.5)GeV) for 200(40)fb
delta M_DM = O(0.5(2)GeV) for 200(40)fb
- Angular distribution
-> clear model separation possible with 200fb
--> studying the effect of mass measurement
- Threshold scan
--> 3-point fit to sigma(rs,n) = a(s-4m^2)^n with n=1/2, 3/2
@ rs=470, 500, 530 GeV with 50fb^-1 each assuming sigma=40fb
Next Step:
- Finish the mass shift study
- Write a paper

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2) LHT: ZHZH (Reported by E.Kato)
- MC Conditions
Same as the previous LHT publication

- e+e- -> ZHZH followed by ZH->AH+H (mH=134GeV) with 500fb^-1
99.5fb for 0 polarization
- BG: WW, tt, WWZ, nunuWW, ZZ, ZH, WHWH
Status:
- AH-ZH 2D Mass fitting
--> 2 solutions: AH mass: 4.2% ZH mass: 1.3%
--> the false solution eliminated by performing simultaneous fit
with WHWH
mass --> AH: 1.3%, WH: 0.20%, ZH: 1.1%
- f fitting
--> f: 0.16%
Next Step:

- Move onto eHeH
Q: How can one test AHAH-h coupling?
A: ZZ fusion?
C: Estimate the measurement error for e-eH-ZH coupling

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Discussions on future direction and mile stones
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*) Oct.18-22: IWLC2010 Meeting
*) BAW meeting on Jan.18-21.

Meeting Schedule:
Next general meeting (2010/11/27 10:30)

 

Working group web page:
http://www-jlc.kek.jp/subg/physics/ilcphys/

Slides are available from http://ilcphys.kek.jp/meeting/physics/