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Contents

  1. Abstract
  2. Authors
  3. Documentation
  4. Technicolor Signal and Cross Section
  5. Event Selection and Search Strategies
  6. Figures
    1. Signal Acceptance and systematic uncertainties
    2. Background estimation
    3. Reconstructed Mass
  7. 95% C.L. Excluded region


Abstract

We present a search for technicolor particles produced in association with W bosons when really technirho decays to a technipion and a W boson with the techniopion decaying to quarks in p-pbar collisions at √s= 1.96 TeV. This search uses data corresponding to an integrated luminosity of 1.9fb-1.
We select double b-tagged W + 2 jets events and one b-tagged W+2jets events. NN flavor separation is applied to one b-tagged events to increase purity of signal events. Three b-tagging categories (double silicon vertex b-tagged events, one silicon vertex b-tagged + Jet Probability b-tagged and one silicon vertex b-tagged w/ NN flavor separator) which have different purity are analized separately.
The observed number of each categories and the invariant mass distributions of W+2 jets and di-jets are consistent with the standard model expectations.
We set a 95% C.L. excluded region as a function of the technicolor particles mass.

Authors:

Yoshikazu Nagai, Shinhong Kim, Tatsuya Masubuchi (University of Tsukuba)
Weiming Yao (LBNL)

Data: Run II, 1.9 fb^-1 --- Collected through May 2007 ---

Docementation

CDF note 9302
ps pdf --- Public note

Technicolor Signal and Cross Section

Feynman diagram
Signal cross section times Branching ratio for neutral/charged &piT

Event selection and Search strategies

Search strategies

Double silicon vertex (SECVTX) b-tag events (ST+ST), one SECVTX b-tag + one jet probability (JetProb) b-tag events (ST+JP) and one SECVTX b-tag with NN flavor separator evens are estimated separately due to taking advantage of the S/N ratio in two double tag categories and one single tag category. The best result is given by combined likelihood of two double b-tagging events and one b-tagging events.

Basic event selection

CategoryDouble SECVTXOne SECVTX + One JetProbOne SECVTX w/ NN
Lepton Central isolated electron or muon and Plug isolated electron (Pt>20 GeV)
Missing Et>20 GeV(Central)
Two Jets>20 GeV, |&eta| < 2.0
b-tagging (1st jet)tight SecVtx b-tagtight SecVtx b-tag w/ NNtag
b-tagging (2nd jet)tight SecVtx b-tagJetProb b-tagNo b-tag
# These three categories are selected exclusively.

Figure


Signal acceptance for neutral &piT channels

Acceptance (%)
m(&rhoT,&piT) (180,95) (190,105) (200,105) (200,115) (210,115) (210,125) (220,115) (220,125) (220,135)
Double SECVTX 0.32 +/- 0.04 0.36 +/- 0.05 0.37 +/- 0.05 0.40 +/- 0.05 0.38 +/- 0.05 0.41 +/- 0.06 0.38 +/- 0.05 0.43 +/- 0.06 0.43 +/- 0.06
One SECVTX + One JetProb 0.23 +/- 0.04 0.25 +/- 0.04 0.25 +/- 0.04 0.27 +/- 0.04 0.27 +/- 0.04 0.28 +/- 0.05 0.26 +/- 0.04 0.29 +/- 0.05 0.29 +/- 0.05
One SECVTX w/ NN 0.66 +/- 0.04 0.72 +/- 0.06 0.70 +/- 0.06 0.73 +/- 0.06 0.76 +/- 0.07 0.78 +/- 0.07 0.76 +/- 0.07 0.78 +/- 0.07 0.81 +/- 0.07

Acceptance (%)
m(&rhoT,&piT) (230,125) (230,135) (230,145) (240,125) (240,135) (240,145) (240,155) (250,135) (250,145) (250,155) (250,165)
Double SECVTX 0.41 +/- 0.06 0.43 +/- 0.06 0.45 +/- 0.06 0.40 +/- 0.06 0.43 +/- 0.06 0.46 +/- 0.06 0.45 +/- 0.06 0.42 +/- 0.06 0.45 +/- 0.06 0.46 +/- 0.06 0.45 +/- 0.06
One SECVTX + One JetProb 0.29 +/- 0.05 0.28 +/- 0.05 0.29 +/- 0.05 0.28 +/- 0.05 0.32 +/- 0.05 0.29 +/- 0.05 0.29 +/- 0.05 0.29 +/- 0.05 0.31 +/- 0.05 0.30 +/- 0.05 0.31 +/- 0.05
One SECVTX w/ NN 0.80 +/- 0.07 0.82 +/- 0.07 0.82 +/- 0.07 0.82 +/- 0.07 0.81 +/- 0.07 0.84 +/- 0.07 0.80 +/- 0.07 0.85 +/- 0.07 0.84 +/- 0.07 0.83 +/- 0.07 0.81 +/- 0.07


Signal acceptance for charged &piT channels

Acceptance (%)
m(&rhoT,&piT) (180,95) (190,105) (200,105) (200,115) (210,115) (210,125) (220,115) (220,125) (220,135)
Double SECVTX 0.04 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.05 +/- 0.01 0.07 +/- 0.01
One SECVTX + One JetProb 0.09 +/- 0.01 0.09 +/- 0.02 0.09 +/- 0.02 0.10 +/- 0.02 0.11 +/- 0.02 0.11 +/- 0.02 0.10 +/- 0.02 0.11 +/- 0.02 0.12 +/- 0.02
One SECVTX w/ NN 0.69 +/- 0.06 0.75 +/- 0.06 0.73 +/- 0.06 0.81 +/- 0.07 0.78 +/- 0.07 0.80 +/- 0.07 0.77 +/- 0.07 0.83 +/- 0.07 0.83 +/- 0.07

Acceptance (%)
m(&rhoT,&piT) (230,125) (230,135) (230,145) (240,125) (240,135) (240,145) (240,155) (250,135) (250,145) (250,155) (250,165)
Double SECVTX 0.06 +/- 0.01 0.06 +/- 0.01 0.06 +/- 0.01 0.06 +/- 0.01 0.06 +/- 0.01 0.07 +/- 0.01 0.06 +/- 0.01 0.06 +/- 0.01 0.07 +/- 0.01 0.06 +/- 0.01 0.06 +/- 0.01
One SECVTX + One JetProb 0.11 +/- 0.02 0.12 +/- 0.02 0.13 +/- 0.02 0.11 +/- 0.02 0.12 +/- 0.02 0.12 +/- 0.02 0.12 +/- 0.02 0.11 +/- 0.02 0.12 +/- 0.02 0.13 +/- 0.02 0.13 +/- 0.02
One SECVTX w/ NN 0.82 +/- 0.07 0.83 +/- 0.07 0.83 +/- 0.07 0.82 +/- 0.07 0.83 +/- 0.07 0.85 +/- 0.07 0.83 +/- 0.07 0.84 +/- 0.07 0.85 +/- 0.07 0.84 +/- 0.07 0.83 +/- 0.07



Systematic uncertainty on the signal acceptance

Systematic uncertainty on the neutral &piT acceptance Systematic uncertainty on the charged &piT acceptance

Background Estimation

Background Summary (Double SECVTX b-tag)

Background Summary (One SECVTX b-tag + one JetProb b-tag)

Background Summary (One SECVTX b-tag w/ NN flavor separator)

Reconstructed Mass

@ Di-jet and W+2jets invariant mass

Dijet mass(left) and W+2jets mass(right) for double SECVTX b-tag

Dijet mass(left) and W+2jets mass(right) for one SECVTX b-tag + one JetProb b-tag

Dijet mass(left) and W+2jets mass(right) for one SECVTX b-tag w/ NN flavor separator


@ Q value (= m(&rhoT) - m(&piT) - m(W) )

Q value for double SECVTX b-tag(left), one SECVTX b-tag + one JetProb b-tag(middle) and one SECVTX tag w/ NN flavor separator(right)


@ 2D plot (Background total)

2-D plots(dijet mass vs Q value) of estimated total background for ST+ST(left), ST+JP(middle) and ST w/ NN flavor separator(right)


@ 2D plot (Data)

2-D plots(dijet mass vs Q value) of observed data for ST+ST(left), ST+JP(middle) and ST w/ NN flavor separator(right)


@ 2D plot (signal m(&rhoT)=200GeV, m(&piT)=115GeV)

2-D plots(dijet mass vs Q value) of expected Technicolor signal for ST+ST(left), ST+JP(middle) and ST w/ NN flavor separator(right)


95% C.L. excluded region

@ We combine three tag categories to obtain the best limit and set the 95% C.L. excluded region as a function of the technicolor particles mass. Next plots show the expected/observed 95% C.L. excleded region as a function of m(&rhoT) and m(&piT).


Yoshikazu Nagai
Last modified: Thu Apr 19 17:22:00 CET 2008