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SUGRA SUGRA Searches Searches
at the Tevatronat the Tevatron
Dan ClaesUniversity of Nebraska
representing theCDF and D0 Collaborations
The Conference on Higgs & Supersymmetry Laboratoire de l'Accélérateur Linéaire
Orsay, FranceMarch 19-22, 1999
“Precise measurement of the positive muon anomalous magnetic moment”(submitted to PRL February 23, 2001)
“Many people believethat the discovery ofsupersymmetry may be just around thecorner. We may haveopened the first tinywindow to that world.”
“We are now 99 percent sure that the present Standard Modelcalculations cannot describe our data.”
= (g2)/2 (SM)=11 659 159.6(6.7)10-10(0.57 ppm) (SM) (exp)= 43(16)10-10
Though just 5½ years ago...
Fig. 2 Rb and Rc data [2] and theSM predictions [5].
M
SUPERSYMMETRYNew symmetry unifying particles of different spin within multiplets -solves “fine-tuning” provided MSUSY < 1 TeV -allows unification of the gauge couplings
-includes quantum gravity
Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs Hchargino W1,2
charged weak boson light Higgs h neutralino Z1,2,3,4 heavy Higgs Hpseudoscalar Higgs Aneutral weak boson Z photon quark q squark qR,L
lepton l slepton lR,L
~
~
~~
~
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
higgsino mass parametertan ratio of VEV of Higgs doublets
• scalar sector described by MANY mass parameters• different SUSY breaking different class of models
01
~ 1
~
MSSM Assumptions:
•SUSY particles are pair produced•Lightest SUSY particle (LSP) is stable
SLBparityR 23)1(
SUSY Symmetry BreakingSUGRA GeV)
•Lightest SUSY particle is
•5 free parametersmo common scalar massm1/2 common squark massAo trilinear couplingtansign(
01
~
pp e e X ~~
pp q g X ~ / ~
m mq g~ ~
m me eR L~ ~
Production has less dependence on SUSYparameters than decays
Squarks/gluinos dominant if kinematically accessible
Cross sections for scalarleptons are small
s 18. TeV
~q
~q
~*q
g
g
g
~q
~q
q
q
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Signal Cross SectionsSignal Cross Sections
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
If light, squarks and gluinos should be copiously produced at the Tevatron
g
g
q*
q
q
g
q
q
q
q
pp q g X ~ / ~
m mq g~ ~
s 18. TeV
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
q
g
0
1q
0
1q
q
Assuming R-partity is conserved, squarks and gluinos can decaydirectly into the LSP (0
1).
or cascade down to the LSP
q
g
q
So that the dominant signature for ppqq, qg, gg + X is jets+ET
q
q
q
q0
2
q
0
1
q
g q
q
1
q
q
0
1
q
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
The 1992-1994 Tevatron RunThe 1992-1994 Tevatron Run
TeV 8.1s
Cross sections for new physics is smallcompared to Standard Model processes
But CDF and D0 both recorded over 100 pb-1 of data
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
The 1992-1994 Tevatron RunThe 1992-1994 Tevatron Run
DØ
Precision tracking: vertexing,b-tagging, lepton identification
Powerful calorimetry: e, , ET
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
D0 MET and Jets AnalysisD0 MET and Jets Analysis
pp q,g jets + ET
•large branching ratio, but suffers from enormous backgrounds•QCD multijet events w/faked ET
• W/Z+jets• t t
Used ET trigger, basic selection criteria:•ET
j1>115, ETj3>25 GeV
•ET>75 GeV •jets and ET not aligned Reduce QCD•HT( i >1Ei
T) > 100 GeV Reduce W/Z•veto isolated with PT > 15 GeV Reduce W/Z
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Jet-EJet-ETT Correlations Correlations
Jet1
Jet2
Jet3
ET
3
1
3.0
2.5
2.0
1.5
1.0
0.5
0.00 0.5 1.0 1.5 2.0 2.5 3.0
MET, Jet1 vs MET, Jet2
Low Et JET MIN Trigger with offline Met > 10 GeV cut
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Jet-EJet-ETT Correlations Correlations
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
D0 MET and Jets AnalysisD0 MET and Jets Analysis Final ET, HT cuts tuned to optimize S / B
across (m0, m1/2) plane79 pb-1 of data analyzed
Expected: 8.33.5 events Observed: 15
Mq > 250 GeV (95% C.L.)
Mg > 260 GeV (Mg=Mq)
Mg > 300 GeV (small mo)
~
~
~
~ ~
Phys.Rev.Lett. 83 4937 (1999); hep-ex/990213
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
D0 MET and Jets AnalysisD0 MET and Jets Analysis
Phys.Rev.Lett. 83 4937 (1999); hep-ex/990213
~
~
~
~ ~
Mq > 250 GeV (95% C.L.)
Mg > 260 GeV (Mg=Mq)
Mg > 300 GeV (small mo)
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
CDF MET and Jets AnalysisCDF 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:•ET>70 GeV
•HT( i >1EiT) > 150 GeV
•Ntrkiso (isolated tracks)=0
•indirect lepton veto
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
ET predominantly from mis-measured QCD events
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
QCD ET comparison:data(JET20+JET50) & predictions(Herwig)
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
CDF MET and Jets AnalysisCDF MET and Jets Analysis
Main backgroundsQCD, W/Z+jets, tt
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
CDF MET and Jets AnalysisCDF MET and Jets Analysis Expected: 76.02±12.8 events Observed 74
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
CDF MET and Jets AnalysisCDF MET and Jets Analysis
Expected: 76.02±12.8 events Observed 74
For mq mg mg > 300 GeV/c2
For mq << mg mg > 570 GeV/c2
For mq >> mg mg > 195 GeV/c2
~ ~
~ ~
~ ~
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton + Jets SearchCDF Dilepton + Jets Search
Squark & gluino cascade decays can also lead to dilepton final states
pp q, g 102+jj
jj + ET
Selection cuts on CDF’s dilepton trigger: 2 isolated leptons, PT > 11, 5 GeV 2 central jets ET > 15 GeV, | | < 2.4 ET > 15 GeV
q
q
~ ~ ~ ~~q
~q
02
1
q
~~
01
~
01
~
Z*W*
g
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton BackgroundsCDF Dilepton BackgroundsHeavy quark and di-boson production
Require LS leptons. Final M cut rejects Z-production.
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
CDF Dilepton + Jets SearchCDF Dilepton + Jets Search
Expect: 0.550.250.08 events
Observe: 0 events
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
Dilepton mSUGRA SearchDilepton mSUGRA SearchSquark and gluino search through dilepton final states
pp SUSY jj + ET
Selection, optimized for different regions of mSUGRA parameter space, made by (52 different) combinations ofET
jet 1,2 > 20 GeV or 45 GeV (optionally, also require ETjet3 > 20 GeV)
ee signatures: ETe1 > 17 GeV, ET
e2 > 15 GeVe signatures: ET
e > 17 GeV, ET > 4 GeV, 7 GeV or 10 GeV
signatures: ET1 > 20 GeV, ET
2 > 10 GeVET > 20, 30, or 40 GeV
q
q
~q
~q
02
1
q
~~
01
~
01
~
Z*W*
g
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
Dilepton mSUGRA SearchDilepton mSUGRA SearchBackground sources• QCD Multijet, W+jets
• estimated from data
• t t , Z + jets SPYTHIA-based Monte Carlo
(FMC0)
108 pb-1 of data analyzed
Mg = Mq > 255 GeV95% C.L. for tan = 2
~ ~
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
Charginos and NeutralinosCharginos and NeutralinosProduction of 1 0
2 will lead to trilepton final states with ET
perhaps the cleanest signature of supersymmetry.
pp q, g 102
+ ET
~ ~ ~ ~1
02
~
~
01
~
01
~
W*Z*
W*
q
q
q
q
1
02
~
~
1~ 0
2~
~0
1~
*
~
01
~
~ ~
q*~
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
Trilepton + Jets SearchTrilepton + Jets Search
Selection cuts : 3 (e,) with PT > 5 22 GeV require Opposite Sign Leptons (CDF) ET > 10 - 15 GeV mass and topological cuts
Both CDF and DO searched for trileptons (e,) in Run I PRL 80, 1591 (1998); PRL 80, 5275 (1998)
Very low background•Drell-Yan + fakes•heavy flavor production•ZZ, WZ
Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France
Trilepton + Jets SearchTrilepton + Jets Search
CDFExpected: 1.20.2Observed: 0
DOExpected: 1.30.4Observed: 0
mm
100<m0<2500 GeV/c2
a) m½=50 GeV/c2
b) m½=75 GeV/c2
c) m½=100 GeV/c2
d) m½=120 GeV/c2
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Run II UpgradesRun II Upgrades
Main injector
Tevatron
DØCDF
Accelerator upgrade
Run I Run IItotal integrated luminosity
120 pb-1 2 fb-1 /2 years (20 fb-1 extended run)
instantaneous luminosity
4 - 20×1030/cm2sec 2×1032/cm2sec
bunch crossing intervals
3.8 sec 132 nsecbeam energy
1.8 TeV 2.0 TeV•complemented by major detector upgrades
Run II has begun with•Fermilab’s Main Injector(commissioned June 1999)•New anti-proton storage ring
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
The DO Detector UpgradeThe 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
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
DO Upgraded TriggeringDO 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 < 100msec)
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
The number of anti-protons in the ring hasbeen 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.
• 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
Time-of-flight added
End Plugextendedto larger
COT replaces CTC
SVX replaced, Si layer added to beampipe, Intermed. Si Layers added
Shower max eddedForward calorimetereliminated
+ New 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
Forward Mini-drift chambers
Shielding
New Solenoid & Tracking:Silicon, SciFi, Preshowers + New Electronics, Trigger, DAQ
Forward ScintillatorCentral Scintillator
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
RunII Squark and Gluino ProspectsRunII Squark and Gluino Prospects
•Multijets with ET remains the dominant signature of q’s & g’s
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.
~ ~
~ ~ ~
With 2 fb-1, DØ and CDF will probe m1/2 up to ~150 GeV
corresponding to Mgluino 400 GeV (for m0<200 GeV)
Run II improvements:1) improved ET resolution
– more hermetic calorimeter (CDF)– better vertexing (DØ)
2) Advanced analysis methods, improved tools
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
RunII Squark and Gluino ProspectsRunII Squark and Gluino Prospects
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Chargino and Neutralino ProspectsChargino and Neutralino Prospects
At large , the lighter tau slepton is lighter than . Then, and
can dominantly decay into final states with via
tan~ ~ , ~ ~ ~
~
1 20
1 20
1
1
Trilepton signatures with
large content
Major backgrounds:W+jets, Z+jets, WZ,…
Critical: large acceptances and high efficiencies for high & low pT leptons including
Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay
Chargino and Neutralino ProspectsChargino 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 >150 GeVfor most of parameter space
Mchargino reach ~200 GeVfor small to medium values of tan