CDF Logo Search for R-Parity Violating SuperSymmetry
in the Multilepton Channel
Exotics Logo

We present a search for R-parity violating Supersymmetry in channels with 3 or more identified leptons. The search is performed under the assumption that supersymmetric particles are pair produced and decay under R-parity conservation while the lightest supersymmetric particle can decay into two charged leptons plus a neutrino via the λ121 or λ122 coupling. The analysis uses 346pb-1 of data collected by the CDF Run II detector at √s = 1.96 TeV. The results are consistent with the Standard Model and interpreted under the mSUGRA framework. Limits are set on the supersymmetric particle masses.

Plots and Tables:

Lepton Types:
TCE: Tight central electron, |η| < 1.1
LCE: Loose central electron, |η| < 1.1
Plug: Forward electron, 1.1 < |η| < 2.0
CMUP: Muon with track + stub in muon chamber, |η| < 0.6
CMX: Muon with track + stub in muon chamber, 0.6 < |η| < 1.0
CMIO: Muon with track only, not fiducial to CMUP and CMX chambers
TM: Triggered muon, CMUP or CMX only

Control Region plots and tables:
Control Region Cuts Failed MC Prediction Data
2 TCE Z 3rd lepton, Z Veto 5682 ± 612 5703
2 TCE No Z 3rd lepton 1117 ± 119 1041
TCE + LCE Z 3rd lepton, Z Veto 7318 ± 800 7483
TCE + LCE No Z 3rd lepton 1426 ± 154 1416
TCE + Plug Z 3rd lepton, Z Veto 6630 ± 735 6536
TCE + Plug No Z 3rd lepton 716 ± 80 709
TM + CMUP Z 3rd lepton, Z Veto 2388 ± 244 2425
TM + CMUP No Z 3rd lepton 453 ± 49 518
TM + CMX Z 3rd lepton, Z Veto 1809 ± 183 1845
TM + CMX No Z 3rd lepton 306 ± 33 325
TM + CMIO Z 3rd lepton, Z Veto 3277 ± 400 3229
TM + CMIO No Z 3rd lepton 505 ± 61 496
TM + TCE 3rd lepton 72.7 ± 7.3 76
TM + LCE 3rd lepton 137.2 ± 19.9 152
TM + PLUG 3rd lepton 51.6 ± 7.2 51
TCE + CMUP 3rd lepton 42.1 ± 4.7 45
TCE + CMX 3rd lepton 24.8 ± 2.8 25
TCE + CMIO 3rd lepton 50.7 ± 7.3 42
2 Ele + X Z Veto 8.8 ± 1.9 12
2 Muon + X Z Veto 5.1 ± 1.2 2
Ele + Muon + X Z Veto 0.55 ± 0.04 0
All trilepton Z Veto 14.4 ± 2.9 14
2 Ele + X Δφ 2.1 ± 0.3 2
2 Muon + X Δφ 1.2 ± 0.2 4
Ele + Muon + X Δφ 0.35 ± 0.04 0
All trilepton Δφ 3.7 ± 0.3 6
3 Lepton + X Z Veto 0.15 ± 0.02 0
3 Lepton + X Δφ 0.006 ± 0.003 0
Control Regions used in the validation of this analysis.

Agreement between data and MC in standard deviations per control region. EPS or GIF
Scatter plot of the MC prediction (y axis) and observed events in data (x axis) for each control region. Every point corresponds to one control region while the vertical error bar corresponds to the combined uncertainty on the data and MC. Horizontal error bars have no meaning and should be ignored. EPS or GIF
Trilepton Z Control Region
  2 Ele + X 2 Muon + X Ele + Muon + X Total
Z/γ* → ee + γ 4.6 ± 0.8 0 0 4.6 ± 0.8
Z/γ* → μμ + γ 0 2.6 ± 0.5 0.15 ± 0.02 2.8 ± 0.5
W + Z/γ* 0.80 ± 0.06 0.35 ± 0.03 0.36 ± 0.03 1.5 ± 0.1
Fakes 3.5 ± 1.7 2.1 ± 1.1 0.04 ± 0.02 5.6 ± 2.8
Total Background 8.8 ± 1.9 5.1 ± 1.2 0.55 ± 0.04 14.4 ± 2.9
Data 12 2 0 14
Trilepton control region with two opposite sign same flavor leptons with 66 < Mll < 106 GeV/c2
Trilepton Δφ Control Region
  2 Ele + X 2 Muon + X Ele + Muon + X Total
Z/γ* → ee + γ 1.9 ± 0.3 0 0 1.9 ± 0.3
Z/γ* → μμ + γ 0 1.0 ± 0.1 0.34 ± 0.05 1.4 ± 0.2
W + Z/γ* 0.030 ± 0.005 0.011 ± 0.002 0.008 ± 0.002 0.048 ± 0.006
Fakes 0.21 ± 0.11 0.14 ± 0.07 0 0.37 ± 0.19
Total Background 2.1 ± 0.3 1.2 ± 0.2 0.35 ± 0.04 3.7 ± 0.4
Data 2 4 0 6
Trilepton control region with two opposite sign same flavor leptons with Δφ > 160o

Following plots: Backgrounds and RpV SUSY MC are stacked unless stated otherwise.
Invariant mass distribution of the leading leptons. Includes Z and Δφ trilepton control regions. EPS or GIF
pT distribution of the first lepton. Includes Z and Δφ trilepton control regions. EPS or GIF
pT distribution of the second lepton. Includes Z and Δφ trilepton control regions. EPS or GIF
pT distribution of the third lepton. Includes Z and Δφ trilepton control regions. EPS or GIF
Δφ distribution of the leading leptons. Includes Z and Δφ trilepton control regions. EPS or GIF
Trilepton invariant mass distribution. Includes Z and Δφ trilepton control regions. EPS or GIF
Missing transverse energy. Includes Z and Δφ trilepton control regions. RpV SUSY MC is not stacked. EPS or GIF
Signal Region plots and tables:
In the plots the backgrounds and RpV SUSY MC are stacked.
Trilepton Events
  λ121 (no μμ+x) λ122 (no ee+x) All
Z/γ* + γ 2.1 ± 0.7 1.2 ± 1.0 2.7 ± 1.0
W+Z/γ* 0.17 ± 0.01 0.14 ± 0.01 0.20 ± 0.1
Z/γ*+Z/γ* 0.066 ± 0.008 0.063 ± 0.008 0.09 ± 0.01
Fakes 0.71 ± 0.35 0.49 ± 0.25 1.0 ± 0.5
Total Background 3.1 ± 0.9 1.9 ± 1.0 4.1 ± 1.1
RpV SUSY Point (λ121) 4.3 ± 0.4 --- 6.1 ± 0.6
RpV SUSY Point (λ122) --- 3.8 ± 0.4 5.5 ± 0.5
Data 5 1 6
Expected and observed events in the trilepton signal region.
RpV SUSY Point: M0 = 250 GeV/c2, M1/2 = 260 GeV/c2, tan&beta = 5, μ > 0, A0 = 0, Mtop = 175 GeV/c2, M0 1 = 99.4 GeV/c2
Invariant mass distribution of the leading leptons. Includes all trilepton signal events. EPS or GIF
pT distribution of the first lepton. Includes all trilepton signal events. EPS or GIF
pT distribution of the second lepton. Includes all trilepton signal events. EPS or GIF
pT distribution of the third lepton. Includes all trilepton signal events. EPS or GIF
Δφ distribution of the leading leptons. Includes all trilepton signal events. EPS or GIF
Trilepton invariant mass distribution. Includes all trilepton signal events. EPS or GIF
4+ Lepton Events
Z/γ* + 2γ 0.0001 ± 0.0001
Z/γ*+Z/γ* 0.004 ± 0.002
Fakes 0.004 ± 0.003
Total Background 0.008 ± 0.004
RpV SUSY Point (λ121) 1.3 ± 0.2
RpV SUSY Point (λ122) 1.3 ± 0.2
Data 0
Expected and observed events in the ≥4 lepton signal region
RpV SUSY Point: M0 = 250 GeV/c2, M1/2 = 260 GeV/c2, tan&beta = 5, μ > 0, A0 = 0, Mtop = 175 GeV/c2, M0 1 = 99.4 GeV/c2

Results:
Mass Limits
  M0 1 (GeV/c2)M± 1 (GeV/c2)
SUSY Scenario Expected Observed Expected Observed
λ121 and μ > 0 105.0 101.5 191.9 185.3
λ121 and μ < 0 101.1 97.7 192.2 185.6
λ122 and μ > 0 107.7 110.4 197.5 202.7
λ122 and μ < 0 102.7 106.3 195.3 201.9
Expected and observed mass lower limits for M1/2 = 260 GeV/c2, tan&beta = 5, μ > 0, A0 = 0, Mtop = 175 GeV/c2
Neutralino mass limit for λ121 and μ > 0. EPS or GIF
Chargino mass limit for λ121 and μ > 0. EPS or GIF
Neutralino mass limit for λ121 and μ < 0. EPS or GIF
Chargino mass limit for λ121 and μ < 0. EPS or GIF
Neutralino mass limit for λ122 and μ > 0. EPS or GIF
Chargino mass limit for λ122 and μ > 0. EPS or GIF
Neutralino mass limit for λ122 and μ < 0. EPS or GIF
Chargino mass limit for λ122 and μ < 0. EPS or GIF


Event Displays:
Tracking view of a trilepton signal region event, Run 50820 Event 3985548. EPS or GIF
Calorimeter η,φ view of a trilepton signal region event, Run 50820 Event 3985548. EPS or GIF
R-Z view of a trilepton signal region event, Run 50820 Event 3985548. EPS or GIF
Tracking view of a trilepton signal region event, Run 163009 Event 110391. EPS or GIF
Calorimeter η,φ view of a trilepton signal region event, Run 163009 Event 110391. EPS or GIF
R-Z view of a trilepton signal region event, Run 163009 Event 110391. EPS or GIF

Page was last updated August 4th, 2006 by Alon Attal.
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