SUGRA Searches at the Tevatron

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SUGRA Searches at the Tevatron
Dan Claes University of Nebraska representing
the CDF and D0 Collaborations
The Conference on Higgs Supersymmetry
Laboratoire de l'Accélérateur Linéaire Orsay,
France March 19-22, 1999
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(No Transcript)
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am (g-2)/2 am (SM)11 659 159.6(6.7)?10-10(0.57
ppm) am (SM)-am (exp) 43(16)?10-10
Precise measurement of the positive muon
anomalous magnetic moment (submitted to PRL
February 23, 2001)
We are now 99 percent sure that the present
Standard Model calculations cannot describe
our data.
Many people believe that the discovery
of supersymmetry may be just around the corner.
We may have opened the first tiny window to that
world.
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Though just 5½ years ago...
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Fig. 2 Rb and Rc data 2 and the SM predictions
5.
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SUPERSYMMETRYNew symmetry
unifying particles of different spin within
multiplets -solves
fine-tuning provided MSUSY lt 1 TeV
-allows unification of the gauge
couplings -includes quantum gravity
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Particle Name Symbol Spartner Name
Symbol gluon
g gluino
g charged Higgs H
chargino
W1,2 charged weak boson light
Higgs h
neutralino Z1,2,3,4
heavy Higgs Hpseudoscalar Higgs
Aneutral weak boson Z
photon g
quark q
squark qR,L
lepton l
slepton lR,L





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Minimal Supersymmetric SM
Extension adding the fewest new particles

• 2 Higgs doublet h0 H0 A0 H
• and described by 4 parameters

M1 U(1) M2 U(2) gaugino mass parameter
at EW scale m higgsino mass
parameter tan b ratio of VEV of Higgs doublets

• scalar sector described by MANY mass parameters
• different SUSY breaking different class of
  models

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MSSM Assumptions

• SUSY particles are pair produced
• Lightest SUSY particle (LSP) is stable

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SUSY Symmetry BreakingSUGRA (L 10 11 GeV)

• 5 free parameters

mo common scalar mass m1/2 common squark
mass Ao trilinear coupling tanb sign(m)

• Lightest SUSY particle is

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Signal Cross Sections
Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Production has less dependence on
SUSY parameters than decays Squarks/gluinos
dominant if kinematically accessible Cross
sections for scalar leptons are small
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
? q
? q
g
? q
g
? q
q
g
? q
q
If light, squarks and gluinos should be
copiously produced at the Tevatron
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
? ? 01
Assuming R-partity is conserved, squarks and
gluinos can decay directly into the LSP (?01).
?
? ? 01
? q
? g
? q
q
q
q
or cascade down to the LSP
q
q
? q
q
? g
q
? q
? ? ?1
? q
? g
q
? ?02
? q
? q
q
q
? ? 01
? ? 01
q
q
?? ?? ??
So that the dominant signature for pp?qq, qg, gg
X is jetsET
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
The 1992-1994 Tevatron Run
Cross sections for new physics is small compared
to Standard Model processes
But CDF and D0 both recorded over 100 pb-1 of
data
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
The 1992-1994 Tevatron Run
Precision tracking vertexing, b-tagging, lepton
identification
Powerful calorimetry e, g, ET
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
D0 MET and Jets Analysis
? ?

• pp ? q,g ? jets ET
• large branching ratio, but suffers from enormous
  backgrounds
• QCD multijet events w/faked ET
• W/Zjets
• t t

• Used ET trigger, basic selection criteria
• ETj1gt115, ETj3gt25 GeV
• ETgt75 GeV
• jets and ET not aligned
  Reduce QCD
• HT(? i gt1EiT) gt 100 GeV Reduce W/Z
• veto isolated m with PT gt 15 GeV Reduce W/Z

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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Jet-ET Correlations
Low Et JET MIN Trigger with offline Met gt 10 GeV
cut
Jet1
3.0 2.5 2.0 1.5 1.0 0.5 0.0
??1
Jet3
??3
???
ET
Jet2
0 0.5 1.0
1.5 2.0 2.5
3.0
???MET, Jet1? vs ???MET, Jet2?
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Jet-ET Correlations
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
D0 MET and Jets Analysis
Final ET, HT cuts tuned to optimize S / ?B
across (m0, m1/2) plane 79 pb-1 of data
analyzed Expected 8.3?3.5 events Observed 15
Mq gt 250 GeV (95 C.L.) Mg gt 260 GeV (MgMq) Mg
gt 300 GeV (small mo)





Phys.Rev.Lett. 83 4937 (1999) hep-ex/990213
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
D0 MET and Jets Analysis
Mq gt 250 GeV (95 C.L.) Mg gt 260 GeV (MgMq) Mg
gt 300 GeV (small mo)





Phys.Rev.Lett. 83 4937 (1999) hep-ex/990213
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
CDF MET and Jets Analysis
starting with basic cuts similar to DO

• Missing ET trigger
• cleanup jets projected to calorimeter gaps
• Blind Box method defines signal region by
• ETgt70 GeV
• HT(? i gt1EiT) gt 150 GeV
• Ntrkiso (isolated tracks)0
• indirect lepton veto

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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
ET predominantly from mis-measured QCD events
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
QCD ET comparisondata(JET20JET50)
predictions(Herwig)
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
CDF MET and Jets Analysis
Main backgrounds QCD, W/Zjets, tt
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
CDF MET and Jets Analysis
Expected 76.0212.8 events Observed 74
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
CDF MET and Jets Analysis
Expected 76.0212.8 events Observed 74
For mq ? mg mg gt 300 GeV/c2 For mq ltlt mg
mg gt 570 GeV/c2 For mq gtgt mg mg gt 195 GeV/c2






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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton Jets Search
Squark gluino cascade decays can also lead to
dilepton final states

?01
q q
? ?


g
?02 ??1 q
pp ? q, g ? ??1?02jj ? ??jj ET
Z W

q q

?01
Selection cuts on CDFs dilepton trigger 2
isolated leptons, PT gt 11, 5 GeV 2 central
jets ET gt 15 GeV, ? lt 2.4 ET gt 15 GeV
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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton Backgrounds
Heavy quark and di-boson production
Require LS leptons. Final M?? cut rejects
Z-production.
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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton Jets Search
Expect 0.55?0.25?0.08 events Observe
0 events
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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
Dilepton mSUGRA Search

Squark and gluino search through dilepton final
states
?01
q q
? ?

g
?02 ??1 q
pp ? SUSY ? ??jj ET
Z W

q q

?01
Selection, optimized for different regions of
mSUGRA parameter space,
made by (52 different) combinations of ETjet 1,2
gt 20 GeV or 45 GeV (optionally, also require
ETjet3 gt 20 GeV) ee signatures ETe1 gt 17 GeV,
ETe2 gt 15 GeV em signatures ETe gt 17 GeV,
ETm gt 4 GeV, 7 GeV or 10 GeV mm
signatures ETm1 gt 20 GeV, ETm2 gt 10 GeV ET gt
20, 30, or 40 GeV
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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
Dilepton mSUGRA Search

• Background sources
• QCD Multijet, Wjets
• estimated from data
• t t , Z jets
• SPYTHIA-based Monte Carlo
• (FMC0)
• 108 pb-1 of data analyzed

Mg Mq gt 255 GeV 95 C.L. for tan b 2

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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
Charginos and Neutralinos

Production of ??1 ?02 will lead to trilepton
final states with ET perhaps the cleanest
signature of supersymmetry.

?01
? ?
q q?

??1 ?02

W
W Z
pp ? q, g ? ??1?02 ? ??? ET

? ?

?01

?01


q q?
??1 ?02

?01


?? ??

?? ?
?02
??1

??
q
??

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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
Trilepton Jets Search

• Very low background
• Drell-Yan fakes
• heavy flavor production
• ZZ, WZ

Both CDF and DO searched for trileptons (e,m) in
Run I PRL 80, 1591 (1998) PRL
80, 5275 (1998)
Selection cuts ? 3? (e,m) with PT gt 5 - 22
GeV require Opposite Sign Leptons (CDF)
ET gt 10 - 15 GeV ?? mass and topological cuts
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Daniel Claes, University of Nebraska
Lincoln Higgs SUSY Conference 2001 Orsay, France
Trilepton Jets Search
CDF Expected 1.2?0.2 Observed 0
DO Expected 1.3?0.4 Observed 0
100ltm0lt2500 GeV/c2 a) m½50 GeV/c2 b) m½75
GeV/c2 c) m½100 GeV/c2 d) m½120 GeV/c2
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Run II Upgrades

• Run II has begun with
• Fermilabs Main Injector
• (commissioned June 1999)
• New anti-proton storage ring

• Accelerator upgrade
• Run I Run II
• total integrated luminosity
• 120 pb-1 2 fb-1 /2 years
• (20 fb-1 extended run)
• instantaneous luminosity
• 4 - 201030/cm2sec 21032/cm2sec
• bunch crossing intervals
• 3.8 ?sec 132 nsec
• beam energy
• 1.8 TeV 2.0 TeV
• complemented by major detector upgrades

DØ
CDF
Tevatron
Main injector
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
The DO Detector Upgrade

• retain the uranium/liquid-argon calorimeter
• retain most of its full-coverage muon system
• But the entire tracking volume is being
  replaced
• shorter bunch spacing,
• higher radiation levels
• New Detector Elements
• inner silicon vertex detector
• 8 layers of scintillating fiber tracking
• 2 Tesla superconducting solenoid
• scintillator-based preshower detecto

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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
DO Upgraded Triggering

• LEVEL 1 (trigger decisions within few ?sec)
• calorimeter trigger unchanged
• new fiber tracker trigger
• adds new preshower detector
• LEVEL 2 (trigger decisions within 100 ?sec)
• global processors run algorithsm
• correlating info from different subdetectors
• e.g., calorimeter-preshower-track matches
• E/p and invariant mass cuts
• Event buffering between each trigger stage
• deadtime due to pileup decreased
• event transfer rates into LEVEL 3 1 kHz
• LEVEL 3
• rejection of 50
• average processing time lt 100msec)

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The number of anti-protons in the ring has been
one of the major limiting factors in Tevatron
luminosity. The anti-proton stacking rate will
be increased to 2x1011/hr from 7x1010/hr The
machine will operate with 36x36 bunches (396 ns
spacing) initially and (132 ns) eventually.
Run II machine goals 1) Run IIa to achieve a
luminosity of 5x1031 cm-2s-1 and an
integrated luminosity of 2 fb-1 2) Run IIb to
achieve a luminosity of 2x1032 cm-2s-1 and
an integrated luminosity of 20 fb-1
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COT replaces CTC
Time-of- flight added
SVX replaced, Si layer added to beampipe,
Intermed. Si Layers added
End Plug extended to larger h
Forward calorimeter eliminated
Shower max edded
New Trigger, DAQ

• a new massive silicon vertex detector
• 7 layers extending to 28 cm in radius
• deadtime-less SVX3 readout electronics
• a new central outer tracker (COT)
• hermetic scintillator tile plug forward
  calorimeter
• large trigger bandwidth

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Central Scintillator
Forward Mini- drift chambers
Forward Scintillator
Shielding
New Solenoid Tracking Silicon, SciFi,
Preshowers
New Electronics, Trigger, DAQ

• entirely new tracking
• improved muon spectrometer
• new trigger and DAQ system

2T super conducting solenoid disk/barrel
silicon detector 8 layers of scintillating
fiber tracker preshower detectors
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
RunII Squark and Gluino Prospects

• Multijets with ET remains the dominant signature
  of qs gs
• Critical
• Understanding the tail of the ET distribution in
  multijet events
• Methods to accurately estimate multijet
  backgrounds
• Large tan? enhanced g /??i /? 0i decays to 3rd
  generation particles
• Critical
• ?-lepton and b-quark trigger and
• identification capabilities.

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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
RunII Squark and Gluino Prospects

• Run II improvements
• improved ET resolution
• more hermetic calorimeter (CDF)
• better vertexing (DØ)
• Advanced analysis methods, improved tools

With 2 fb-1, DØ and CDF will probe m1/2 up to
150 GeV corresponding to Mgluino ? 400 GeV
(for m0lt200 GeV)
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Chargino and Neutralino Prospects
Trilepton signatures with large ?
content Major backgrounds Wjets, Zjets,
WZ, Critical large acceptances and high
efficiencies for high low pT leptons
including ?
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Daniel Claes, University of Nebraska-Lincoln
Higgs SUSY Conference 2001, Orsay
Chargino and Neutralino Prospects
Run II improvements
1) extended coverage improves lepton acceptances
2) lepton charge and better ? momentum
measurements reducing backgrounds (DØ) 3) new
preshower detectors 4) major effort on ?
identification built upon Run I
experiences
Mchargino reach gt150 GeV for most of parameter
space Mchargino reach 200 GeV for small to
medium values of tan?