di-bosons and anomalous couplings at d0
DESCRIPTION
Di-bosons and Anomalous Couplings aT D0. Heidi Schellman, Northwestern University. Slide on Tevatron context. D Ø Detector. Lepton ID in the D Ø Detector. muon system Coverage to h =2. shielding. electronics. Liquid argon active medium and uranium/copper absorber - PowerPoint PPT PresentationTRANSCRIPT
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DI-BOSONS AND ANOMALOUS COUPLINGS AT D0Heidi Schellman, Northwestern University
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Slide on Tevatron context
DØ Detector3
Lepton ID in the DØ Detector muon system
Coverage to h=2
shielding
electronics
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Liquid Argon Calorimeter5
Liquid argon active medium and uranium/copper absorber Hermetic with coverage for:|h| < 4.2 Longitudinal and Transverse segmentation h x x X0 =
0.1x0.1x ~1 (0.05x0.05 in third EM layer, near shower maximum)
h=1.1
h=1.5
ICR
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Lagrangian for neutral (ZZγ/Zγγ)
□□
CP conserving → h3,4V couplings (V = γ, Z)
: SM :Deviations SM
Allowed Anomalous
γ
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Lagrangian for charged (WWγ/WWZ)
EM gauge inv. (g1γ = 1), C and P conserving 5 couplings: κV, λV, g1
Z
W/γ/Z
W/γ/Z
Allowed Additional Anomalous
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Wγ and Zγ D0 has excellent
photon identification due to fine transverse and longitudinal segmentation in the calorimeter.
Neural network discriminant yields > 90% purity in Zγ
PRL 107, 241803 (2011)
(photon ET > 15 GeV, dR(lγ) > 0.7)
Wγ → lνγ Production
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pb0.27.6:SM@NLO σ
Radiation 0
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Anomalous Wγ couplings
95% CL limits on TGCs:
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Zγ vvγSelect interactions with large,
significant Missing transverse momentum
Zγ vvγ avoids radiation off of the Z!
Limits on the anomalous couplings of Z’s to photons.
Phys. Rev. Lett. 102, 201802 (2009)
Zγ → llγ Production12
Mllγ > 110 GeV (FSR removal):
( ) fb 65401089llZBR (syst)(stat) Zγσ
( ) fb 1115288llZBR (syst)(stat) Zγσ
unfolded
unfolded
fb341096 :SM@NLO σ
fb10294SM@NLO σ:
Phys. Rev. D 85, 052001 (2012)
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Zγ mmγ
Combine with ννγ
95% CL limits on TGCs
Fit the pt distribution to limit anomalous couplingsCombine with the ννγ channel for improved limits.
Three high pT (isolated) leptons (μμμ, eee, eeμ, μμe) +MET
SM@NLO: σ = 3.21 ± 0.19 pb (60 < Mll < 120 GeV)
WZ → lνll Production14
Phys. Rev. D 85, 112005 (2012)
ZZ → llll Production15
Cross section for the ZZ production using fully leptonic final states • Four high pT leptons (μμμμ, eeee, eeμμ)
SM@NLO: σ = 1.40 ± 0.10 pb
ZZ → llll10 events.37 background
Phys.Rev.D84:011103,2011
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ZZ → ννll Production16
Challenges in ννll final states: • MET reconstruction• WW background
ZZ → ννll
SM@NLO: σ = 1.40 ± 0.10 pb
Phys. Rev. D 85, 112005 (2012)
ZZ → vvll
Result: ννll (8.6 fb-1):
Optimal variable is a modified pT with negative corrections proportional to resolutions (ie. pT
d < 0)
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ZZ → ννll Production
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Challenges in ννll final states: • MET reconstruction• WW background
ZZ → ννll
SM@NLO: σ = 1.40 ± 0.10 pb
Phys. Rev. D 85, 112005 (2012)
ZZ → vvll
Optimal variable is a modified pT with negative corrections proportional to resolutions (ie. pT
d < 0)Combined: llll (6.4 fb-1)+ννll (8.6 fb-1):
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Tevatron WZ and ZZ cross sections
WZ ZZ
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Summary of Bosons at the Tevatron
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Summary Diboson cross sections have been
measured in many all-leptonic channels Future updates
Full statistics ZZ Full statistics WW Anomalous couplings using all channels
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BACKUP SLIDES
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Older D0 limits on anomalous couplingsfrom Wγ, WW, WZ
Can be interpreted as measurements of the magnetic dipole and quadrupole moments.
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Prospects for the future D0 and CDF are updating to
the full statistical sample. Done for WZ and ZZ channels
Combining channels and experiments will increase the TGC sensitivity by a factor of 3-5.
LHC experiments have 10 times the cross section 10 fb-1 of data factor of 10 in statistics and 3 in sensitivity.
Proving ground for analysis techniques and statistical treatment used in the Tevatron Higgs searchesComplementary to Higgs production(same final states/challenges)
Probe of the EWSB mechanism• Test of the SM• Indirect searches for New PhysicsCross sections, Kinematic distributions, Trilinear Gauge Boson Couplings (TGCs)
Important background to: • Top• Higgs • Beyond the SMGood understanding is highly valuable
mH < 135 GeV
mH > 135 GeV
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Motivation for Diboson Studies
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D0 – set charged TGC limits using pt in 4 channels
WZ→lvll
Wγ→lvγ
WW lvjjWW→lvlv
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Charged Triple Gauge CouplingsProbed by WW, WZ, and Wγ productionGeneral Lagrangian has 14 parametersAssume EM gauge invariance and C and P conservation⇒ 5 TGC parameters: g1
Z, kγ, kZ, λγ, λZ
g1 and k are 1 in the SM, the rest are zero
Neutral Triple Gauge CouplingsProbed by ZZ and Zγ productionGeneral Lagrangian has 8 TGC parametersAssume CP conservation⇒ 4 non-SM TGC parameters: h3
γ, h3Z, h4
γ, h4Z all
0 in SM
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ννγ candidate event
γ
MET
γ
1060204 %d0%bb%d0%b8%d1%81%d1%82%d0%be%d0%b2%d0%ba%d0%b0 %d0%bf%d0%be %d1%82%d0%b5%d0%bf%d0%bb%d0%be
%d0%92%d1%96%d0%b4%d0%bf%d0%be%d0%b2%d1%96%d0%b4%d1%8c %d0%9e%d0%b1%d1%83%d1%85%d1%96%d0%b2 %d0%bf%d