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Date/Time: 10:30~17:30 JST, Jan. 24, 2015
Place: Room 425, Building No.3, KEK
Official Language: English
Video Conference ID: 883 (KEK MCU2)
Fuze connection: http://fuze.me/27597634
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A Summary of The 40th General Meeting of the ILC Physics Subgroup
Jan. 24, 2015 (Sat) at Room 425, Building 3, KEK
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0) Attendants:
Present at KEK:
C.Calancha (KEK)
K.Fujii (KEK)
J.Tian (KEK)
M.Nojiri (KEK)
T.Ogawa (Sokendai)
K.Hidaka (Gakugei)
T.Suehara (Kyushu)
K.Ikematsu (Saga)
A.Sher (KEK visitor)
Remote connection:
K.Tsuchimoto (Shinshu)
S.Kawada (Hiroshima)
Y.Sudo (Kyushu)
T.Tomita (Kyushu)
0) Opening comments (K.Fujii)
1) Higgs to tau tau (Shin-ichi Kawada)
Status:
Current numbers:
250fb-1@ 250GeV
3.4% qqh
32.4% vvh
14.4% eeh
11.3% mmh
Today: 500GeV
new event reconstruction strategy
*) tau finder first and then kT clustering
5.0% (cut-based) 4.6% (TMVA: BDTG) : qqh
Next:
- Improve tau finder.
- Other modes: vvh, eeh, mmh.
2) Top Yukawa coupling study at 500 GeV (Yuji Sudo)
Check the presentation at the Annual Tokusui WS.
3) Higgs self-coupling: 1TeV vvhh (Junping Tian)
Status:
Condition: Ecm=1TeV, mh=125GeV
BG: tt -> lvbbqq, vvZZ, vvZh -> vvbbbb
W/o overlay, compare the results with the extrapolation
-> 3.6 sigmas (extrapolation was 3.7 sigmas)
W/ overlay (<N>=4.1@1TeV)
-> Higgs mass much wider than the case w/o overlay.
-> R=1.2 (but not satisfactory)
-> 2.7 sigmas (25% degradation!)
Next Step:
- Solve the overlay problem
- Improve analysis techniques
Optimize the selection for self-coupling not for cross section.
4) ZH: Recoil mass using Z->qq (Taikan Suehara/Tatsuhiko Tomita)
Status:
ZH->qqH @250GeV
ISR finder
Tau finder
Cuts: mass box for ZZ, WW BGs.
Z mass
major/minor thrusts
Previous Result (LCWS)
-> delta sigma / sigma = 4.7% (Left pol), 3.3% (right pol)
Today
-> Tried 3 methods, cut-based, likelihood, and BDT
(-0.8,+3) : delta sigma / sigma = 2.5%
(+0.8,-3) : delta sigma / sigma = 2.2%
-> efficiency difference still large (maximum a few %) for 0lep 0tau category
Next Step:
- Improve the bias due to efficiency differences.
- Study the effect of bias for different BSM models.
5) Impact of QFV on H->cc in MSSM (Keisho Hidaka)
Full 1-loop in MSSM with non-minimal QFV
Key parameters: 4 QFV and 1 QFC parameters
-> There can be a large deviation from SM in Gamma(h->cc).
Q: Why is the deviation so large?
A: Due to the large enhancement coming from the top Yukawa contribution
possible only in the QFV case (no such enhancement in the QFC case).
Q: You assume m_gluino of 1.5TeV. What happens if m_gluino is, say, 3TeV?
A: There is a scaled up scenario where you can expect a similar large deviation
in such a case, too.
6) Anomalous HVV couplings (Tomohisa Ogawa)
Status:
Trying to reproduce Takubo’s result.
Signal: e+e- -> Zh -> vv WW* -> vv4q
Event selection
6-variable MVA:
#PFOs, -logY23, -logY34, E_missing, costh_h, Pt_h
flavor tagging: remove b’s and require 2c
Phi (angle between two decay planes of W’s) reconstruction
Mass fit in each phi bin to get #signals.
-> Mass fit seems reasonable
-> Shape difference observed between generated and reconstructed
phi distributions.
First try to see the sensitivity of phi measurement to anomalous couplings.
Next Step:
- Compare the data selection with Takubo’s analysis and make sure that the selection
is at least as good as the previous analysis before moving on to the anomalous coupling
studies.
- Check the phi angle calculation.
7) enW (Koya Tsuchimoto)
Motivations:
Detector benchmark (JER)
Direct mW measurement
Anomalous WWA, WWZ couplings
Status:
Ecm=250GeV, 250fb-1
Generator level study
mW distribution well modeled by a BW with running width.
Reconstructed mW mass
Observed asymmetry in the mW distribution:
most probably from missing neutrinos and detector effects
-> neutrino effects have been confirmed by looking at mW for
W->cs and W->ud separately.
studying the effects of lepton rejection
Mass scale calibration using Z->qq
Next Step:
- Reduce the effect of missing neutrinos.
- Jet energy calibration.
- Study systematic errors.
C: Check the polarization used for the cross section calculation.
8) High level reconstruction (Masakazu Kurata)
Status:
Now focusing on
Vertex mass recovery -> OK
Flavor separation in 0 vtx case
Vertex finding (with vtx charge assignment)
- 0 vtx case: Signed impact parameter
K from D: larger impact parm, more collinear to jet axis, more energetic.
-> BNess tagger (developed in CDF) -> How to do bc separation?
BNess (Track MVA to ID tracks from heavy flavor)
BNess = BNess(bl)+BNess(bc)
-> bc separation is better for +ve impact parameter than -ve.
Particle ID
Just taking highest score tracks does not work very well
except for lepton tracks (~soft lepton tagger)
Mass using BNess tracks (mass with final BNess>0.8)
- Vertex finding:
vtx charge:
-> slight (a few %) improvement for the fraction of correct charge assignment.
No. of 2vtx jets increased.
-> seems some problem with PandroPFA (cluster only unattached tracks)
Next:
- 0 vtx case:
- Use particle type to improve BNess tagger.
- Think about how to use BNess for flavor tagging.
9) Discussions: all
See slides by Junping.
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The slides shown at the meeting is available from
http://agenda.linearcollider.org/conferenceDisplay.py?confId=6422
see them for details.
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*) Meeting Schedule:
Next general meeting (2015/04/11 10:30) : Conf.ID: 742
Working group web page:
http://www-jlc.kek.jp/jlc/en/subg/physics