Searches For Supersymmetry with the DZero Detector at the Fermilab Tevatron
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Searches For Supersymmetry with the DZero Detector at
the Fermilab Tevatron
Mark S. Cooke (Columbia U.)
on behalf of the D0 collaboration
SUSY10Bonn, Germany23rd August, 2010
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2SUSY Searches at D0, M.S. Cooke (Columbia U.)
DZero and the TevatronTevatron: collisions at TeV
Over 9 fb-1 has been delivered in Run II !
DZero: well understood, multi-purpose detector
Designed with the flexibility to observe beyond SM signatures in a variety of final states
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Outline
Charginos & neutralinos in trileptons +
GMSB signature in
Hidden Valley SUSY, “lepton-jets” +
Bottom squarks in
Top squarks in
Sneutrinos as an resonance in R-parity violating SUSY
SUSY Searches at D0, M.S. Cooke (Columbia U.)
D0 has recently performed SUSY motivated searches in several interesting final states,
(also interpreted in a UED context)
(also interpreted in a leptoquark context)
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4SUSY Searches at D0, M.S. Cooke (Columbia U.)
Search for charginos and neutralinos in the trilepton final state
2.3 fb-1 [PLB 680 (2009) 34]
“Classic” SUSY signature:• 3 isolated leptons+MET
• Small SM backgrounds
Major challenge is to achieve high efficiency in 3 lepton selection:
3rd leading lepton can be quite soft
Search categories:• 2 leptons (e.g. ee, μμ, eμ) + isol. track (l)
• μτ + isol. track (l)
• μτ + τhad
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5SUSY Searches at D0, M.S. Cooke (Columbia U.)
Trileptons (cont’d)Results
(3) BR to τ increases with tan(β) (2) Scan mSUGRA model mass relations,2 and 3 body decays possible
Neutralino/chargino mass relations
generally
(2)
(3)
(1)
(1) 3 body decays: 2 cases shown, slepton masses “just” and “way” above chargino mass
“just above”
“way above”
No evidence for signal, limits
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Search for gauge mediated supersymmetryin the final state
SUSY Searches at D0, M.S. Cooke (Columbia U.)
New! 6.3 fb-1 [arXiv:1008.2133]
In GMSB, SUSY masses
Gravitino doesn’t carry SM gauge very light (LSP)
Chargino/Neutralinoproduction and cascade decays as in trilepton
analysis, but also
SM Backgrounds:
• No genuine
• Genuine
SM γγ, γ+jet, multi-jet
Estimated with data
missed ele track (W+γ,jet)
W/Z+γγ (MC)
NLSP (prompt decay)
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7SUSY Searches at D0, M.S. Cooke (Columbia U.)
(cont’d)GMSB Results
For ,
expect: 6.9 ± 1.0 eventsobserve: 4 eventsSPS8 GMSB: 5.2 ± 0.4 events @ Λ=120 TeV
Consistent w/ SM expectation,In SPS8 context, limit (95% C.L.)excludes:
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1st Level Kaluza-Klein (KK) Statesafter rad. corr.
SUSY Searches at D0, M.S. Cooke (Columbia U.)
(cont’d)UED interpretation
UED predicts a tower of KK states for each SM field, separated in
mass by If UED in higher dim. space, grav. decays are induced. Assume:
95% C.L. limit excludes:
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9SUSY Searches at D0, M.S. Cooke (Columbia U.)
Search for Hidden Valley SUSY in final stateswith “lepton-jets” and 5.8 fb-1 [D0 Note 6079-CONF]
• Hidden valley models predict a weakly
coupled sector with a “dark photon”
force carrier which decays to “lepton-jets”.
• Can appear in SUSY context in decay chains:
Previous search for
Here
PRL 103 081802 (2009)
Dark LSPs
Lept
on-je
t
D0 Preliminary
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10SUSY Searches at D0, M.S. Cooke (Columbia U.)
Search for bottom squark production in the final state
• Strong production of sbottom pairs
• assumed
• Decay kinematics set by
0
Challenging Final State!
5.2 fb-1 [arXiv:1005.2222]
After b-tagging and selections to reduce MET mismeasurements, major backgrounds are from:
• W/Z+cc/bb
• top processes
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(cont’d)
SUSY Searches at D0, M.S. Cooke (Columbia U.)
Leptoquark interpretation
SUSY Results
Exclude at 95% C.L.
Charge ⅓ 3rd Generation Leptoquark
for 100%
for equal couplings
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12SUSY Searches at D0, M.S. Cooke (Columbia U.)
Search for top squark production in the final state
After cut, sensitivity
assessed in 2D plane:depending on
diff. rejection of WW and top
vs.
• Strong production
of stop pairs
• Assume, 3-body
eμ sample
3.1 fb-1 [D0 Note 5937-CONF]
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13SUSY Searches at D0, M.S. Cooke (Columbia U.)
Search for R-parity violating (RPV) production of a sneutrino resonance in the final state 5.3 fb-1 [arXiv:1007.4835]
Process probes trilinearRPV couplings:
• Jet veto reduces top bkgd.
• Events with
rejected if
Remaining bkgd primarily DY(ττ) at low Meμ and diboson at high Meμ.
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Conclusions
Chargino and neutralino pair production (tri-lepton, GMSB diphoton)
Stop and bottom pair production
Some special scenarios - RPV and Hidden Valleys
+ new interpretations outside the SUSY context
See also talks by F. Couderc (SUSY Higgs), S. Banerjee (long-lived)
SUSY Searches at D0, M.S. Cooke (Columbia U.)
With a large dataset and a well understood detector,D0 continues the hunt for SUSY!
No signals so far, but... best limits to date in several channels.
Reported here today D0 searches for:
Tevatron to run through 2011, expected to deliver 12 fb-1
And new searches and further updates are also on the way!