supersymmetry at the tevatron
DESCRIPTION
CDF. D0. Supersymmetry at the Tevatron. R. Demina University of Rochester. 20 years of SUSY. And still, no one is prettier… “We like the way she walks, We like the way she talks” but… God damn it, where is she?. Outline. Data sets Tri-leptons Jets and missing energy Straight up - PowerPoint PPT PresentationTRANSCRIPT
CDF
D0
Supersymmetry at the Tevatron
R. DeminaUniversity of Rochester
2
20 years of SUSY
And still, no one is prettier…“We like the way she walks, We like the way
she talks” but…God damn it, where is she?
3
Outline
• Data sets• Tri-leptons• Jets and missing energy
– Straight up– With heavy flavor
• Gauge Mediated SUSY Breaking – photons with missing energy
• Long-lived particles• Conclusions
4
Run II data taking
Presented analyses are based on pre-shutdown data<200pb-1
5
SUSY production at Tevatron
• 200 pb-1
– 1013collisions– 80 chargino/ neutralino
(3l) events produced– 800 squark/gluino events
produced
• To control backgrounds searches based on “signatures”: 3 or more physics objects
TEl 3~~1
02
TEjetsqqgg ~~,~~
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Tri-leptons
• Chargino/neutralino production – three leptons and missing energy signature
• Main challenge - weak production low cross sections– LEP limits are very restrictive
• Need extremely well controlled backgrounds
3e 2e
3 2e
ee(l) e(l)
• Leptonic branching are enhanced if sleptons are lighter than gauginos
(l ) – isolated track = e,
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ee+lepton
2 Electrons: EM cluster+track match• PT>12 (8) GeV• ||<1.1 (3.0)
1. Anti-Z– 15<Mee<60 GeV (ee)<2.8
2. Anti-W(e)+– >=1hit in silicon or tighter
electron likelihood
3. Anti tt– Veto jets with ET>80GeV
4. Anti-Drell Yan– Missing ET>20GeV (eMET)>0.4
Potential signal
175pb-1
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ee+lepton
5. Lepton = isolated track:– PT>3GeV
6. Etmiss x PT(track)>250GeV
(signal)=2-3%
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Tri-leptons
• Summary after all cuts:
Channel
Data Total SM background
e e l 1 0.270.42 0.02
e 1 2.490.37 0.18
e l 0 0.540.24 0.04
1 0.130.06 0.02
Add isolated track with PT>3 GeV
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Combined tri-leptons
• Run 1 cross section limit much improved• Soon will reach MSugra prediction (in the best scenario
with low slepton masses)
11
Jets and missing energy
• Squarks and gluions: • Strong production
– larger cross section, – but really large instrumental
backgrounds (2 orders of magnitude over SM processes)
•4 events left 2.67 expected from SM sources (Z/W production)•17.1 event expected for M0=25,M1/2=100GeV
85 pb-1
2 jets ET>60 (50) GeV30<(jet,MET)<165o
Final cuts:Missing ET>175 GeV
HT>275 GeV
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Squarks and gluinos
• M0=25GeV; A0=0; tan=3; <0
M(gluino)>333GeVRun 1 – 310 GeV
M(squark)>292GeV
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B-jets and missing energy
• High tan() scenario under study: sbottom is lighter than other squarks and gluino
•4b-jets+missing energy
•>=3jets (ET>10 GeV)•Missing ET>35 GeV
•1 b-tag– 5.6+-1.4 events SM predicted - 4 observed
•2 b-tags –0.5+-0.1 events SM predicted - 1 observed
01~~
;~~~~ bbbbbbgg
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Met
• Gauge mediated SUSY breaking at scale
• Gravitino – LSP• NLSP (neutralino) LSP• Dominant SUSY mode:
185 pb-1
Signature – 2 photons, missing energyPT(photon)>20 GeV in ||<1.1
1 event survived 2.5±0.5 expected from SM
Missing ET>40 GeV
GeVm
GeVm
TeV
180)(
105)(
8.78
1
01
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Long Live Particles!
• LSP – charged particle, or• NLSP – charged particle (e.g. stop) with long decay time• Signature – isolated track of a rather slow particle• Use TOF system (CDF)• BG prediction of 2.9 +/- 0.7 (stat) +/- 3.1 (sys), with 7 observed
d
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Conclusions
• Tevatron detectors produce solid physics results based on datasets of up to 185 pb-1
• SUSY limits extended beyond run 1:– In trilepton signature – Missing energy and jets– Missing energy and b-jets– GMSB in diphoton final state
• New system (TOF) used to search for long lived particles