Squark/Gluino Analysis
IFAE-Barcelona
IFAE-Barcelona


Authors

Monica D'Onofrio (donofrio@fnal.gov)

Gianluca De Lorenzo (gdl@fnal.gov)

Mario Martinez (mmp@fnal.gov)

Xavier Portell (portell@fnal.gov)

CDF, FNAL,
P.0. Box 500, M.S. 318
Batavia, Illinois 60510
USA


Search for Squark/Gluino Production in MET+jets Final State
(1.1 fb-1 analysis)

We are reporting on the search for squarks and gluinos in a mSUGRA scenario assuming R-parity conservation with a sample of 1.1 pb^-1 of CDF Run II data. The analysis is optimized for three jets and missing transverse energy (MET) signature. Events are required to have

  • MET > 70 GeV + cleanup cuts
  • At least three jets with ET > 25 GeV and |&eta|<2.0
  • At least one jet central |&eta| < 1.1
  • Jet EM Fraction < 0.9
  • Δφ (MET-jet)> 0.7 (all three leading jets)
  • No reconstructed Z from tracks and no isolated tracks with Δφ (MET-track)< 0.7


MET distribution after different requirements

Three different set of cuts are defined to increase sensitivity in different zones with increasing gluino mass. The thresholds for the transverse energy (ET) of the jets, the MET and the scalar sum of the ET of the three main jets (HT) are quoted below:

  • Type Zone A:  ET1 > 95 GeV ;  ET2 > 55 GeV ;  ET3 > 25 GeV ; MET > 75 GeV ;  HT > 230 GeV
  • Type Zone B:  ET1 > 120 GeV ; ET2 > 70 GeV ;  ET3 > 25 GeV ; MET > 90 GeV ;  HT > 280 GeV
  • Type Zone C:  ET1 > 140 GeV ; ET2 > 100 GeV ; ET3 > 25 GeV ; MET > 120 GeV ; HT > 330 GeV

No excess with respect to Standard Model predictions is found.

Table of number of events in data vs SM expectations after final cuts

A preliminary 95% C.L. exclusion plane has been produced where masses below 380 GeV/c^2 are excluded in the region where gluino and squark masses are similar.

  • Public Note (under construction)


  • EXCLUSION PLANES

    • Exclusion Plane (Gluino Mass vs Squark Mass) gif & eps
      Exclusion Plane for squark and gluino masses at 95 % C.L. The theoretical uncertanties on the mSUGRA NLO cross sections are included in the limit calculation . The red area denotes the region excluded by this analysis. The green dashed area is the exclusion region after ISR/FSR uncertainties in the signal and top background are included. The black dashed line is the expected limit.

    • Exclusion Plane (Gluino Mass vs Squark Mass) (a la D0) gif & eps
      Exclusion Plane for squark and gluino masses at 95 % C.L. The theoretical uncertanties on the mSUGRA NLO cross sections are NOT included in the limit calculation . The red area denotes the region excluded by this analysis. The yellow band denotes the exclusion limit taking into account 1 &sigma variations in the mSUGRA NLO cross sections. The green dashed area is the exclusion region after ISR/FSR uncertainties in the signal and top background are included. The black dashed line is the expected limit.

  • PROSPINO CROSS SECTIONS VS OBSERVED/EXPECTED 95% C.L. LIMITS

    • Cross section as a function of Gluino Mass (Squark Mass about 460 GeV/c2) gif & eps
      PROSPINO NLO Cross section as a function of the gluino mass for a squark mass about 460 GeV/c2. The yellow band denotes the systematic uncertainty on the theoretical predictions. Solid and dashes lines denote the observed and expected 95 % C.L. The theoretical predictions ARE INCLUDED in the limit calculation. The exclusion limit is therefore determined by the cross point between the observed/expected curve and the NOMINAL NLO prediction.

    • Cross section as a function of Gluino Mass (Squark Mass ~ Gluino Mass) gif & eps
      PROSPINO NLO Cross section as a function of the gluino mass. The yellow band denotes the systematic uncertainty on the theoretical predictions. Solid and dashes lines denote the observed and expected 95 % C.L. The theoretical predictions ARE INCLUDED in the limit calculation. The exclusion limit is therefore determined by the cross point between the observed/expected curve and the NOMINAL NLO prediction.

    • Cross section as a function of Squark Mass (Gluino Mass about 200 GeV/c2) gif & eps
      PROSPINO NLO Cross section as a function of the squark mass for a gluino mass about 200 GeV/c2. The yellow band denotes the systematic uncertainty on the theoretical predictions. Solid and dashes lines denote the observed and expected 95 % C.L. The theoretical predictions ARE INCLUDED in the limit calculation. The exclusion limit is therefore determined by the cross point between the observed/expected curve and the NOMINAL NLO prediction.



  • MISSING ET AND HT DISTRIBUTIONS WITH FINAL CUTS (N-1 plots)

    • Missing ET distribution for analysis cuts type A gif & eps and stack plot gif & eps
      Missing Et Distribution after final cuts type A (but the one of the MET). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on MET placed. The stack plot gives additional details on the contribution from the different SM processes.

    • Missing ET distribution for analysis cuts type B gif & eps and stack plot gif & eps
      Missing Et Distribution after final cuts type B (but the one of the MET). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on MET placed. The stack plot gives additional details on the contribution from the different SM processes.

    • Missing ET distribution for analysis cuts type C gif & eps and stack plot gif & eps
      Missing Et Distribution after final cuts type C (but the one of the MET). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on MET placed. The stack plot gives additional details on the contribution from the different SM processes.

    • HT distribution for analysis cuts type A gif & eps and stack plot gif & eps
      HT Distribution after final cuts type A (but the one of HT). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on HT placed. The stack plot gives additional details on the contribution from the different SM processes.

    • HT distribution for analysis cuts type B gif & eps and stack plot gif & eps
      HT Distribution after final cuts type B (but the one of HT). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on HT placed. The stack plot gives additional details on the contribution from the different SM processes.

    • HT distribution for analysis cuts type C gif & eps and stack plot gif & eps
      HT Distribution after final cuts type C (but the one of HT). The data is compared to SM predictions (separated also in QCD and non-QCD backgrounds). The band presents the total systematic uncertainty on the background prediction. For illustrations, the signal for a typical mSUGRA point is shown. The arrow indicates where is the cut on HT placed. The stack plot gives additional details on the contribution from the different SM processes.

  • CONTROL REGIONS DEFINED USING REVERSED CUTS

    • MET Distribution when Δφ (MET-jet) < 0.7 (at least for one of the jets)
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps)
      Events are required to have at least one jet with azimuthal direction aligned to the direction of the MET (QCD dominated region)

    • HT Distribution when Δφ (MET-jet) < 0.7 (at least for one of the jets)
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps) ;
      Events are required to have at least one jet with azimuthal direction aligned to the direction of the MET (QCD dominated region)

    • MET Distribution when Jet EM Fraction is > 0.9 (at least for one of the jets)
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps)
      Events are required to have at least one jet with electromagnetic fraction larger than 0.9 (selects electrons, EWK/TOP dominated region)

    • HT Distribution when Jet EM Fraction is > 0.9 (at least for one of the jets)
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps) ;
      Events are required to have at least one jet with electromagnetic fraction larger than 0.9 (selects electrons, EWK/TOP dominated region)

    • MET Distribution when there is at least one isolated track with Δφ (track-MET) < 0.7
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps)
      Events are required to have at least one isolated track pointing in the direction of the MET (selects electrons and muons, EWK/TOP dominated region)

    • HT Distribution when there is at least one isolated track with Δφ (track-MET) < 0.7
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps) ;
      Events are required to have at least one isolated track pointing in the direction of the MET (selects electrons and muons, EWK/TOP dominated region)

  • DETAILS ON SIGNAL-to-BACKGROUND OPTIMIZATION AND EFFICIENCIES

    • S/sqrt(B) in the MET and HT plane for
      Type A cuts (gif & eps) ; Type B cuts (gif & eps) ; Type C cuts (gif & eps) ;
      For a significant mSUGRA point the profile of s/sqrt(B) values is presented as a function of MET and HT. The lines indicate the selected thresholds.

    • Efficiency of the selection criteria gif & eps (along the diagonal)
      The efficiency of the different selection criteria are presented along the diagonal in the squark/gluino mass plane. The lines indicate the thresholds.

    • S/sqrt(B) for the selection criteria gif & eps (along the diagonal)
      S/sqrt(B) for the different selection criteria are presented along the diagonal in the squark/gluino mass plane.

            Mario Martinez (mmp@fnal.gov)