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Tevatron SUSY Results
E. Nagy Centre de Physique des Particules de
Marseille
On behalf of the CDF and D0 Collaborations

• Introduction
• Chargino-Neutralino searches
• Slepton searches
• Gluino-squark searches
• Conclusion

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Introduction
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SUper SYmmetry
Symmetry of Nature for Bosonlt-gtFermion
interchange Basic ingredient for unification
with gravity (SuperString/M-theory) The only
nontrivial extension of the Lorentz-Poincaré
group Provides elegant solution to evade the
fine tuning problem Minimal extension of the SM
MSSM every SM particle has ?S ?1/2 partner
R (-1)3BL2S 1 (SM) -1 (SUSY) 2nd
Higgs doublet is needed (treated in the Tevatron
Higgs talk)
R -1
R 1
If SUSY were exact only 1 additional parameter
(µ) needed
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SUSY is a broken symmetry since nobody has seen
the partners many more parameters describe
breaking with additional hypotheses they are
reduced in models treated here, e.g.
gravitation mediated (mSUGRA) model to 5 (m0,
m1/2, tanß, sgnµ, A0) gauge mediated (mGMSB)
model to 6 (?, Mm, N5, tanß, sgnµ, Cgrav)
parameters In most cases R-parity is assumed to
be conserved since there are severe limits on
B- and L-violating processes Then SUSY
partners are pair produced LSP is
stable (neutral and weakly interacting) dark
matter candidate Basic signature is MET (LSP),
multiple jets or leptons from cascade decays
of the heavy R-1 partners Main bg is t tb,
gauge boson production in pair or with
jets Violation of R-parity is not excluded. This
would allow single resonant formation of SUSY
particles produce many more jets/leptons in
final state in B- and L-violating processes
add additional parameters (48 Yukawa
couplings) At the Tevatron both RPC and RPV have
been studied
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Tevatron
Run IIa ended in March 2006 full dataset 1.3
fb-1 (10x Run I) Run IIb started in June 2006
hoping to reach 4-8 fb-1 by 2009
Analyses with Lint gt 0.3 fb-1 are reported here
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D0
CDF
Electron ID hlt2.4 (w/ track) ID eff. 80-90
Electron ID hlt3.6 (hlt2 w/ track) ID eff.
80-90
Photon ID hlt2.4 (hlt1.1 w/ CPS) ID eff.
85
Photon ID hlt2.8 ID eff. 80
Jet ID cone alg. hlt4.0
Jet ID cone alg. hlt3.6
HF tag lepton-tag hlt2.0 vertex-tag hlt2.4
HF tag lepton-tag hlt1.0 vertex-tag hlt1.5
Muon ID hlt2 ID eff. 90-100
Muon ID hlt1 ID eff. 90-100
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Chargino-Neutralino searches
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Chargino (?1) and Neutralino (?20) RPC pair
production
Production also via sq (t-channel) Decay
can be also 2-body msl lt m?20, m?1
signature 3l (isolated e,µ,t or track (3rd l))
MET or 2l (SS e,µ) MET (if 3rd
lepton is too soft)
Both CDF and D0 has searched for this signal on
1fb-1 dataset
Data are well described at the preselection
stage and in control regions Ex. D0 eel
analysis pTe1 gt12 GeV pTe2 gt 8
GeV
Main backgrounds Z/?jets QCD
(multijets) WW,WZ ttbar
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Since s x BR are small several channels are
combined
After cuts to supress the background and enhance
the signal data are compatible with the expected
background in all analyses
DØ Analysis channels Luminosity (fb-1) Total predicted Background Observed data
eetrack 1.2 0.82?0.66 0
??track 0.3 1.75?0.57 2
e?track 0.3 0.31?0.13 0
??/ ?-?- 0.9 1.1 ? 0.4 1
e?track 0.3 0.58?0.14 0
??track 0.3 0.36?0.13 1
Chargino mass limit in mSUGRA inspired models
considerably improved
3l-max Msl slightly above M?20 and Msl
degenerate M? gt 140 GeV heavy-sq destructive
t-channel contribution minimal M? gt 155 GeV
For large m0 sls are heavy and small BR into
leptons
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CDF Analysis channels Luminosity (pb-1) Total predicted Background Observed data
e?e?,e???, ???? 710 6.80?1.00 9
?? e/? (low-pT) 310 0.13?0.03 0
eetrack 610 0.48?0.07 1
ee e/? 350 0.17?0.05 0
?? e/? 750 0.64?0.18 1
?e e/? 750 0.78?0.15 0
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Chargino (?1) and Neutralino (?20) pair
production
Lightest neutralino (?10) is allowed to decay via
RPV ?ijkLiLjEck
More leptons (less MET) than in RPC case ?
better sensitivity
One assumes 1 non-zero coupling at a time ?121,
?122 (CDF,D0), ?133 (D0) sufficiently large that
decay w/o displaced vertex
CDF has searched events with 4 leptons has found
0 with expected bg 0.0080.004
D0 has found 0 events in channels eel
µµl (l e, µ) eet with bg 0.9 0.4
0.4 0.1 1.3 1.8
mSUGRA limits by D0 (L 0.36 fb-1) CDF has
obtained somewhat smaller limits
t identification validated in Z? t t
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Longlived neutralino (?10) pair production
If ?122 sufficiently small ?10 may live
long producing a displaced vertex in 5-20 cm from
the interaction points by the µµ pair NuTeV has
reported 3 events of µµ pairs
D0 has adequate vertex reconstruction
acceptance x efficiency determined with KS
Observed 0 events 2 muons pTgt10 GeV, cosmic
veto, good vertex in 5 lt rT lt 20 cm DCA gt 0.01
from any other vertex Background 0.751.6 (w/
syst) estimated from data extrapolating from 0.3
lt rT lt 5 cm and inverting the DCA
cut Systematics estimated by changing the
selection criteria
The obtained 95(99) xsection upper
limit excludes the interpretation of the
NuTeV events as being longlived neutralinos
M?105GeV
L0.38 fb-1
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GMSB
Expected signal vs M2? messenger mass
scale (N51, tanß15, µgt0, Cgrav?short lifetime)
Select 2 photons pT gt 25 GeV (1 w/ PS hit)
Signal is at high MET MET gt 45 GeV Data 4 Bg
2.10.7
Previous CDF-D0 combined limit improved by
D0 m?10 gt 120 GeV m?1 gt 220 GeV
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GMSB
N51, tanß15, µgt0, M2?
CDF searches for longlived NLSP ? 10
by looking for a  late  photon of pTgt30 GeV in
the calorimeter accompanied with MET (G) ( gt 50
GeV) and with a jet (from the other SUSY
particle) of pTgt30 GeV
t0 is the arrival time of prompt particles in the
calorimeter time resolution 0.6 ns
With an optimal timing cut of 1.5 ns one observes
10 data events expecting 7.6 1.9 background
events
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AMSB
D0 has studied chargino pair production if M? -
M?10 lt 150 MeV
These charginos live long (CMSP) appear as
muons in the detector, but they are slower
vp/E ?arrive later in the muon
detector Speed significance (sps) (1-v)/sv
(st2-3ns)
Select 2 muons pTgt15 GeV at least 1
muon isolated cosmic ray veto
sps gt 0 for both muon cut
optimized in the Mµµ vs sps1sps2 plane
depending on the CMSP mass
Background are muons of missmeasured time
estimated from data Z? µ µ
Data is compatible with expectation of the SM No
event observed beyond MCMSPgt100 GeV typical
background 0.600.05 (depending slightly on the
mass)
Exclude M? lt 174 GeV (gaugino-like)
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Slepton searches
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GMSB
D0 limits for CMSP is applied to long lived stau
(NLSP) pair production
With the parameters ? 19?100 TeV, Mm 2 ?,
N53, tanß15, µgt0, Cgrav1
95 upper limits of stau pair production no mass
limit yet
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Resonant smu/snuµ search in RPV production and
LSP (?10) decay via non-zero ?211L2Q1Dc1 term
Max. excluded sl mass GeV For min. ?211 coupling strength
210 0.04
340 0.06
363 0.10
Select 2 isolated muons pT1gt15, pT2gt8 GeV gt1
jet pTgt15 GeV Reconstruct ?10 (leading µ
2j) sl (2 µall jet) No signal observed
good agreement with SM Exclusion for mass
and coupling derived
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Resonant snut search in RPV production
(?311L3Q1Dc1) and decay (?132L1L3Ec2 )
Select Isolated muon pTgt20 GeV
electron pTgt20 GeV Reconstruct snut (e-mu) No
signal observed good agreement with
SM Exclusion for mass and coupling derived
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Gluino-squark searches
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Search for generic Squarks and Gluinos in the
multi-jet -- MET topology (D0)
Search for high MET and HTSjetET events in 3
regions of mSUGRA
Small m0 Msq lt Mgl 2 acoplanar jets (gt60,50
GeV) HTgt275, METgt175 GeV Msq Mgl
3 jets (gt60,40,30 GeV) HTgt350,
METgt100 GeV Large m0 Mgl lt Msq 4 jets
(gt60,40,30,20 GeV) HTgt225, METgt 75 GeV
Calculate limits
Data and SM bg are in agreement 2jet
6 4.84.5-2.1 3jet 4
3.91.5-1.3 4jet 10 10.32.4-2.9
Theoretical cross section reduced by its
uncertainties
3-jet
4-jet
Mgl gt 241 GeV/c2 Msq gt 325 GeV/c2
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1st and 2nd generation Squarks and Gluinos in
the jet-MET topology (CDF) optimized for 3 jets
A  ET1 gt 95 GeV  ET2 gt 55 GeV  ET3 gt 25
GeV MET gt 75 GeV  HT gt 230 GeV B  ET1 gt
120 GeV ET2 gt 70 GeV  ET3 gt 25 GeV MET gt
90 GeV  HT gt 280 GeV C  ET1 gt 140 GeV ET2
gt 100 GeV ET3 gt 25 GeV MET gt 120 GeV HT gt
330 GeV
Data and MC agrees in all 3 zones
ZONE C
Mgl gt 387 GeV/c2 (when MglMsq)
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Stopping gluinos
In Split-SUSY s-scalars are heavy gluinos are
light, copiousely produced longlived fragment
into (charged) R-hadrons loose energy - stop in
the detector and decay

• Data selection
• Trigger on jet
• No signal in luminosity monitors
• No reconstructed vertex
• No reconstructed cosmic muons
• Jet in ?lt0.9, 90 GeV lt E lt 900 GeV
• and ? widths of the jet gt0.08 (wide jets)
• Background mainly due to cosmic muons w/o
• reconstructed muons
• Estimated from narrow jet events P(nomu) 0.1

No excess in data over expected
background Determine cross section and mass
limit vs M?1050,90,200 GeV
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Search for s-bottom quarks from gluino
pair-production
4 b-jets and MET
Require 3 jets with ETgt15 GeV, ?lt2
at least 2 jets with b-tag
METgt80 GeV
Data agrees with SM background Verified in 3
control regions, dominated by W/Zjet, QCD and
top production
Published limit is based only on inclusive
double b-tag events
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Search for pair-production of s-bottom quarks
2 acoplanar b-jets and MET
Require 2 jets with acoplanarity ?flt 165o
ET1gt40 GeV, ET2gt15 GeV,
?1lt0.9 at least 1 jet with
b-tag METgt80 GeV
Isolated lepton veto
Data agrees with SM background w/ and
w/o b-tagging
Final ETj and MET cuts are increased as
function of the s-bottom mass
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• CDF selection for the same channel
• 2 or 3 jets
• Et cuts on 1st and 2nd leading jets vary
  depending on Msb
• METgt50 GeV or higher depending Msb
• 1st and 2nd leading jets not back-to-back
• Jets not pointing along direction of MET
• ?1 jet tagged JetProbability lt 1

Low Msb Medium Msb High Msb
SM (Total) 55.07.24 17.82.31 4.670.67
Data 60 18 3
MET145 GeV
Et55 GeV
JP8.2 10-6
Et100 GeV
JP6.6 10-3
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Search for pair-production of stop
quarks decaying into blsnu (le,µ)
Stop may be the lightest squark due to large
mixing thanks to large top mass Its 3-body decay
into blsnu through virtual chargino dominates
for light snu D0 has studied bbeµMET and
bbµµMET final states in MSSM framework
Main selection for µµ 2 isolated OS muons
cosmic veto pT1gt8GeV, pT2gt6GeV At least 1 jet
pTgt15 GeV leading jet b-tagged METgtMinMET(?F(µ1,
MET)) Mµµ outside the Z mass region Data is
compatible with SM
Main selection for eµ gt1 isolated electron
pTegt12 GeV gt1 isolated muon pTµgt8 GeV MET gt
15 GeV not in the direction of the
leptons MT(e,MET) gt 15 GeV
Combined limit extends significantly regions
excluded earlier
Exclusion limit determined on STpTepTµMET and
Non Isolated Tracks
Exclusion limit determined on HTSpTj
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Search for pair-production of stop
quarks decaying into c?10
This decay mode dominates for mcm?10 lt mst lt mb
MW m?10
Basic event topology 2 acoplanar c-tagged jets
pT1gt40 GeV, pT2gt20 GeV optimized ?f(j1,j2) lt
165o MET gt 40 GeV optimized for mst-m?10 pairs
get minimal ltCLsgt, expected signal confidence
in absence of signal QCD background is small
extrapolated from low MET
In general data agrees with the SM prediction A
visual scan of the high MET events did not reveal
any anomaly
Obtained limit on mst _at_ 95 improves
significantly domains excluded earlier
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• CDF selection for the same channel
• 2 or 3 jets
• Et cuts on 1st and 2nd leading jets vary
  depending on Mst
• METgt50 GeV or higher depending Mst
• 1st and 2nd leading jets not back-to-back
• Jets not pointing along direction of MET
• ?1 jet tagged JetProbability lt 5

Low Mst Medium Mst High Mst
SM (Total) 13715.8 94.911.1 42.75.28
Data 151 108 43
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Search for pair-production of stop
quarks decaying into bt via RPV (?333)
Basic event topology 1 t decays leptonically
isolated e or µ 1 t decays hadronically track
em cluster Njet gt 1 ST pTlpTtMET gt 110 GeV
against QCD and Z? t t background MT(l,MET) lt
35 GeV against Wjet background Mll outside
Z mass region 2 events seen 2.260.460.22
expected from SM
L0.32 fb-1
Upper limit of cross section x BR(100)
derived Mass limit Mst gt 155 GeV obtained also
valid for 3rd generation LQ3
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Conclusions
Thanks to the Tevatron the regions where there
is no need to look for SUSY have increased
considerably
The former LEP and Run I mass limits have been
significantly extended
The searches continue with increasing
luminosity, with better performing detectors,
exploring event topologies with ever increasing
sophistication in a friendly competition between
the two experiments