Model ID @ 500 GeV
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Transcript of Model ID @ 500 GeV
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 1
Model ID @ 500 GeVModel ID @ 500 GeV
Taikan SueharaICEPP, The Univ. of Tokyo
Taikan Suehara, 16th 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: AH (vector)
– Visible: WH± (vector)
Three modelsThree models
All give 2W + 2WIMP fs.
Taikan Suehara, 16th 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 overviewAnalysis overview
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 4
ILDILD detector &detector & frameworkframework
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 reconstructi
on
• Tracking• Particle Flow• Flavor tagging etc.
Analysis
Stdhep event files
Particle information (ROOT tree)
• Event weighting• Separation cuts• Analysis (mass, angle…)
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 5
• Signal: JSF/physsimStructure
• 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 generationEvent generation
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 6
Selection cutsSelection cuts
• 4-jet clustering (Durham)• # Track >= 20• 160 < Evis < 400 GeV• each Ejet > 5GeV• |cos|jet < 0.99• unlike 3jet (yth,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 < mW < 95 GeV
BG suppression cuts
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 7
Selection efficiencySelection 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
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 8
W energy distribution (for W energy distribution (for mass)mass)
MC truth (signal only)
Reco (kin-fitted)MC & reco have a good correlation.Difference of shapes (esp.WH) is notused for the discrimination in this analysis.
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 9
Mass determinationMass determination
Fitting: 3rd polynomial x Voigt function (10 params)
1.All 10 params free2.Fix 8 params (except edge positions):obtain errors of the edge positions
Taikan Suehara, 16th 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 resolutionMass resolution
Low edge(200 fb)
High edge(200 fb)
Low edge(40 fb)
High edge(40 fb)
IH 97.00 ± 0.13 GeV
174.22 ± 0.19 GeV
97.86 ± 0.38 GeV
176.22 ± 0.84 GeV
SUSY 97.12 ± 0.15 GeV
173.46 ± 0.21 GeV
96.10 ± 0.54 GeV
176.02 ± 0.85 GeV
LHT 96.94 ± 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)
IH 232.28 ± 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)
SUSY 232.59 ± 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)
LHT 232.18 ± 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)
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 11
• Production angle of the visiblenew particle can be calculatedfrom W directions with massesof new particles andback-to-back assumption.
• The angle has spin info.but two-fold ambiguity (solution of 2nd equation) exists.
Production angleProduction angle
Taikan Suehara, 16th 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 distributionDiscriminant distribution
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 13
• MC & reco have reasonable correlation.• Three models seem to be
discriminated.
1D distribution1D distribution200fb
Taikan Suehara, 16th general meeting of ILC physics (Asia) wg., 2010/07/17 page 14
2D distribution (2 solutions)2D distribution (2 solutions)
SUSYIH
LHT SMBG
Chi-square can be derived using these distributions.
Taikan Suehara, 16th 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 Di and Ti
Separation powerSeparation power
Taikan Suehara, 16th 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 resultsSeparation power results
Uncertainty from statistics : ~2Uncertainty from statistics : ~.3
Taikan Suehara, 16th 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 measurementEffect of mass measurement
IH 40fb IH 200fb
Taikan Suehara, 16th 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…Results…
Taikan Suehara, 16th 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 (ECM-ETH)0.5 response while
IH/LH has (ECM-ETH)1.5 response.
Threshold scanThreshold scan
Taikan Suehara, 16th 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 scanStrategy for threshold scan
Taikan Suehara, 16th 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 resultsChi-square results
Power of 0.5 Power of 1.5
Taikan Suehara, 16th 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 work
Summary/statusSummary/status