20080906-e

--------------------------------------------------------------------------------
A Summary of The 22nd General Meeting of the ILC Physics Subgroup
Sep.3, 2011 (Sat) at Room 425, Building 3, KEK
--------------------------------------------------------------------------------
0) Attendants:
A.Ishikawa (Tohoku)
E.Kato (Tohoku)
A.Yamamoto (Tohoku)
T.Tanabe (Tokyo)
T.Suehara (Tokyo)
R.Katayama (Tokyo)
H.Ono (NDU)
S.Kawada (Hiroshima)
Y.Okada (KEK)
J.Tian (KEK)
S.Kikuta (Sokendai)
Y.Yamamoto (Sokendai)
R.Yonamine (Sokendai)
P.Posh (Sokendai)
H.Parada (LIPI)
D.Harada (KEK)
K.Fujii (KEK)

Via video conf. system:
W.Yamaura (Shinshu)
K.Kotera (DESY)

------------------------------------
Opening Comments
------------------------------------
------------------------------------
Reports from Subgroups
------------------------------------
0) Composite Higgs Search at the ILC (Y.Kikuta)
- Strongly interacting light Higgs
SM + NGB effective theory
xi := v^2/f^2
- VL VL scattering
A(WLWL -> WLWL) = CH (s+t)/f^2
A(WLWL -> ZLZL) = (WLWL->hh) = CH s/f^2
-> blow up with energy
Sum rule valid for fusion processes
- Anomalous couplings
Next Step:
- Low E precision measurements?
- Beam polarization/angular analysis

------------------------------------

[A] Symmetry breaking & mass generation
------------------------------------

1) ZH subgroup
1-1) xxH analysis: BR measurements (Reported by H.Ono)
Status:
- Setup: mh=120GeV,
250fb^-1@250 and @350GeV, Pol(e+,e-)=(+30%,-80%)
- Results of BR (cc/bb) measurements with improved statistics
delta BR(bb)/BR(bb) = 2.7% (250GeV)
delta BR(cc)/BR(cc) = 8.7% (250GeV) -> 6.7% (350GeV)
delta BR(WW*)/BR(WW*) = 15.7% (250GeV)
- Now drafting a journal paper.
- Trying to extrapolate to mH = 140GeV
delta BR(bb)/BR(bb) = 7.1% (250GeV)
delta BR(cc)/BR(cc) = 16.1% (250GeV)
delta BR(WW*)/BR(WW*) = 10.9% (250GeV)
- nnH @ 1TeV strategy
Next Step:
- Publication
- Full simulation for different masses
- nnH @ 1TeV
--> WL, ZL, H as new particles to be probed by high virtuality probe.

2) ZHH subgroup (Reported by J.Tian)
2-1) ZHH @ 500GeV
Status:
- Previous analysis
mH=120GeV, 2ab^-1
--> excess significance: 3.9 sigma
--> delta sigma_ZHH = 0.22+/-0.07fb (32%)
--> delta lambda/lambda = 57% (= 1.8 x delta sigma/sigma)
- Different mH (125, 130, 135, 140)
cross section drop with mH
51% drop of BR(H->bb) for mH=140 as compared to mH=120GeV
--> 1 sigma excess significance for mH=140GeV
--> 1.9 sigma excess significance even if we could double the signal efficiency
--> Need to use H->WW* mode
Next Step:
- Publication of the current results
- Plan for the future improvements
jet clustering, b-tagging, jet paring, lepton ID
- nnHH @ 1TeV
- different mH
- Task force formed
Bi-weekly meeting
C: Check the sensitivity to self-coupling as a function of Ecm.

-----------------------------------
2) AA->HH Group
2-1) Experiment (Reported by Kawada)
Status:
- Improved event selection by using jet-pairing hypothesis-dependently:
Pair jets regarding an event as signal (4b BG) and calculate observable.
Improved NN by adding more observables relating to event shapes.
--> significance: 1.92 (1.43) for optimistic (pessimistic) 4b for real jet-clustering
--> significance: 5.59 (5.49) for cheat jet-clustering
Next step:
- Check NN systematics
- Heavier Higgs.
--> Write a paper.
- Improve b-tagging & jet-clustering.

------------------------------------
3) TTH Subgroup (Reported by T.Tanabe)
Status:
- Different mH
sigma_TTH(Ecm=500GeV) = 0.45fb (mH=120GeV), 0.224 (130GeV), 0.084 (140GeV)
BR(H->bb) = 68% (120), 53% (130), 34% (140)
--> scale factor = 1 (120), 0.38 (130), 0.094 (140)
--> significance = 9.6% (120), 23% (130), 86% (140)
--> We definitely need to include H->WW*
--> Increasing Ecm will help.
Next Step:
- Full simulation
- 1TeV
- mH=140GeV using H->WW*

------------------------------------
[B] New physics
------------------------------------
1) LHT subgroup (Reported by E.Kato)
- Setup (MC Conditions):
Same as the previous LHT publication (f=580GeV, mH=134GeV, kappa=0.5)
Status:
- Worked out the strategy for AHZH, WHWH, ZHZH, eHeH, nHnH
- Coupling studies
Assume that WH and ZH decays 100% to AH
--> eeHZH, eeHAH couplings from ZHZH & AHZH
--> VeHeH (V=A,Z), neHWH from eHeH
--> VWHWH (V=A,Z), enHWH from WHWH
--> Gamma_tot(neH) from nHnH
- Method
Prepare templates by knowing acceptance function for the angular distributions
in the triangular region of the two cos(theta) solutions.
Next Step:
- Template fitting and derive the sensitivities to the couplings.

------------------------------------
2) Very light gravitino (Reported by R.Katayama)
Setup:
m_gravitino = <F>/Mpl/3^{1/2} with 1/<F> ~ 1/(Mpl m_{3/2})
-> directly connected to the SUSY breaking scale.
m_gravitino = O(1)-O(10)eV
-> interesting allowed region
hep-ph/9503210
ILC signal:
NLSP=stau
ctau ~ 100 microns
Want to measure ctau, from which m_gravitino is extractable
given the stau mass is measured beforehand by E_tau, etc.
Simulation & Analysis:
Measure the deviation of the impact parameters for the tau decay products
from the SM prediction.
Status:
- Prepared a signal generator
- BG: tau+tau-, W+W-, Z0Z0, two-photon tau+tau-
- Event selection using full sim. samples
--> Look at impact parameter distributions for tau+tau- & mu+mu- BG.
--> Cuts on Evis, Pt, acoplanarity, angle/Evis: essential to suppress AA->tau+tau-
--> AA->tau+tau- :suppressed from O(10^9) to 5000.
Next Step:
- Mass and lifetime fits
C: Try to use e+/e- veto to suppress AA->tau+tau-

------------------------------------
3) Long lived sat (Reported by W.Yamaura)
Status:
- Event Selection
Added dE/dx cut, planning to add TOF cut
-->
Next Step:
- Try right-handed e- polarization
- Add TOF cut
- Include other BGs
- Try to reconstruct M_chi0

---------------------------------------------------------
The slides shown at the meeting is available from
http://ilcphys.kek.jp/meeting/physics/
see them for details.
---------------------------------------------------------

------------------------------------
Discussions on future direction and mile stones
------------------------------------
*) Scheduled talks at LCWS2011
ZH: Ono
Model ID: Suehara
AAHH: Kawada
Long lived sat: Yamaura
LHT: Kato
Meeting Schedule:
*) LCWS2011 Meeting: September 26-30, Granada
Next general meeting (2011/11/05 10:30) : Conf.ID:919

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

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