susy searches at thetevatron peter ratoff lancaster university
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04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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SUSY Searches at theTevatronPeter Ratoff
Lancaster University
CDF, DØ and Tevatron Status New Run I SUSY Results First Glimpse of Run II Data
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Main Injector & Recycler
Tevatron
Chicago
p source
BoosterCDF
DØ
p
p
p p
1.96 TeV
CDFDØ
The Fermilab Tevatron Collider
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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4.82.32.5interactions/xing
1323963500bunch xing (ns)
10517.33.2 Ldt (pb-1/week)
5.2x10328.6x10311.6x1030typ L (cm-2s-1)
1.961.961.8s (TeV)
140x10336x366x6#bunches
Run 2bRun 2aRun 1b
The Tevatron Run 2
Tevatron upgrade: Increased energy
1.8 TeV 1.96 TeV Increased luminosity
0.1 fb-1 2 fb-1 15 fb-1
Detector upgrades: Higher event rates and
backgrounds (electronics, DAQ, trigger)
Considerable expansion of the physics capabilities(Run 1) (Run 2a) (Run 2b)
Physics opportunities: Top Higgs New Phenomena Electroweak Beauty QCD
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
4date
Inte
gra
ted
Lu
min
osi
ty (
pb
-1)
2002 Projected Integrated Luminosity
Considerable fraction (~25%) of collected luminosity devoted to detector commissioning.
Significant progress in identification of “physics objects”: e, , jets, electromagnetic and jet energy scales, etc.
Run 2 in 2001/2002
Currently: Finishing detector commissioning Completing triggers and improve DAQ Debugging, calibration, alignment Refining reconstruction algorithms … Also looking forward to more
integrated luminosity!!!
DØ roll-in
Run II start
First Collisions
Detector Commissioning;Timing in; Improve electronics, DAQ and offline
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The Upgraded DØ Detector
Builds on the strengths of DØ: Excellent calorimetry with faster readout Upgraded muon system for better -ID
Augments its tracker and trigger capabilities: Inner tracking (silicon tracker, fiber tracker)
with 2T superconducting solenoid Preshowers Pipelined 3-level trigger
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SUSY models
SUSY is the best motivated scenario today for physics beyond the Standard Modeldoesn’t contradict precise Electroweak datapredicts light Higgsunification of gauge couplings at GUT scaleessential element of String Theories… provides explanation of Cold Dark Matter in the Universe!
SUSY must be broken symmetry (otherwise MSUSY = MSM)variety of models proposed - differ mainly in the nature of the “messenger interactions”most experimental results obtained in the context of the SUGRA and GMSB models
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SUSY Phenomenology at Hadron Colliders
Physics environment and expected SUSY phenomenology are quite different at e+e- and Hadron collider machines
production expected to dominatesquarks and gluinos are quite heavy decay via multi-step
cascades 0
1
0
2
~~
Zqqqqqqg
~~~~~~
,, gggqqq
many high PT jets and leptons plus large missing transverse energy
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SUGRA models
SUSY breaking is communicated to the physical sector by gravitational interactions
GUT scale parameters + RGE’s low-scale phenomenologyM0 = common scalar massM1/2 = common gaugino massA0 = common trilinear coupling valuetanratio of the V.E.V. of the two Higgs doubletssign of = Higgsino mass parameter
LSP is lightest neutralino - a neutral WIMP excellent CDM candidate
Highly constrained
minimal SUGRA
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Single Electron Channel
g~
g~
q
q
g
q'q
q
01
~
01
~ee
1~
02
~
q
Sensitive to moderate m0
Complements dilepton and Jets+MET channels
Bckg: W+jets, qcd multijet, ttCuts: Et
e >20 GeV,Etj >14 GeV
( 4), no isolated muons, MET > 25 GeVL = 92.7 pb-1
Observed events = 72Expected background = 80 ± 10DØ
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Single Electron Channel
DØ
A0 = 0, < 0 , tan = 3
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Stop Search
Final state: 2 leptons+jets+MET
Drell-Yan, heavy quark pair prod.,QCD fakes, diboson production
Assume sneutrino is LSP...
Mixing between SUSY partners of tL and tR is
proportional to mtop large mixing lighter SUSY
state experimentally accessible
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Stop Search (II)
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R-parity and its violation
Discrete quantum number R = (-1)3B+2S+L ; is 1 for SM particle,-1 for
sparticles
R-parity violation can be introduced by WL=1 = (1/2)ijkLiLjēk+' ijkLiQjđk+' iLiHu
WB=1 = (1/2)'' ijkūiđjđk
Decay of the LSPSignatures maybe very differentSingle sparticle production possibleWhither dark matter candidate
mSUGRA with RPVOne RPV coupling dominatesIf coupling large enough, resonant prod.Otherwise pair production
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Decays of Stop Pair
Assuming RPV only in 3rd gen.tt+X = l + b + h + b + XFinal state: lepton + hadronic + 2 jets
Bckg: W/Z + jets, multijet, dibosonCuts: pT
lepton >10 GeV,h cluster>15, MT
(lepton,Met)<35GeV/c2,HT>70, 2jets (ET >15 GeV)L = 106 pb-1
Bilinear RPV (“BRPV”) stop + b
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Decays of Stop Pair
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Pair Production: di-muon channel
01
~~
c
s
'222
Final state: 2 + 4jets
•Bckg: Drell-Yan, tt, Z+jets, Z•Cuts: pt
>15(10) GeV,ptjets >15 GeV,
•St > 150 GeV,M >5 GeV,Acoplanarity>0.03•Run1 L = 77.5 ± 4 pb-1
Events observed = 0Expected bckg. = 0.18 ± 0.03 ±0.02
DØ
No missing ET
LSP
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Pair Production: di-muon channel
DØ
Run IIa projection
2 fb-1
< 0 , A0 = 0 , tan = 2
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Resonant Production:di-muon channel
u 1o~
L
~
d_
u d
'211
u d
d 1-~
+
~
d_
l -
l
W -
1o~
_
_
Resonant prod. and decayof LSP via RPVFinal state: 2+ 2jets
Bckg: tt, Z+2jets, WW+jetsCuts: pT
>20 GeV, pTjets >20 GeV,
ST >50 GeV, R(-jet) > 0.5L = 94 ± 5 pb-1
Observed events = 5Expected bckg = 5.34 ± 0.07
D
Large RPV coupling
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Resonant Production:di-muon channel
Run IIa projection
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GMSB models
‘Messenger’ sector couples to source of SUSY-breaking and physical sector of MSSM (through gauge interactions)
The identity of the NLSP and its lifetime determine the phenomenology
~ ~ GSMT CFT CAL
Tracks as we know Kinks Large dE/dx
Hot cell c
Photons as we know Impact
parameter
~ ~ 10 G
slepton
llG
c
NLSP
neutralino
G
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Light Gravitino Search
Final state: MET+jet
Bckg: mismeasured multi-jets W/Z + jets, tt, dibosonCuts: MET >50 GeV, removalof events w/ isolated tracks, (MET,jet) >90o, Et
lead-jet >80GeV, 0.1 < EMFlead-jet < 0.95L = 87 pb-1
CDF
qq GGg
qg GGq
gg GGg
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Light Gravitino Search (II)
For MET >175 GeV:Events observed = 19Expected bckg = 21.6
(PTĞĞ >100GeV) < 3.1pb
F > 217 GeVmĞ > 1.1 x 10-5 eV/c2
CDF
04/09/02 SUSY at the Tevatron IDM2002 Peter Ratoff
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Di-photon Channel
Final state: 2 photons + MET
Bckg: multijet, direct photons,W, W+jets, ZeeCuts: ET
>20 GeV,ET >12 GeV,
recon. Vertex, MET>25 GeVL = 106.3 ± 5.6 pb-1
Events observed = 2Expected bckg = 2.3 ± 0.9
D
Neutralino pair production
G 0
1
Publ. 1998
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Di-photon Channel (II)
D
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Di-photon Channel (III)
Run II
MET
D Run IIpreliminary
~ 10 pb-1
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Summary
Comprehensive searches for SUSY have been carried out at the Tevatron exploiting the Run I data to the fullest.
A new era is beginning ...First preliminary Run II Results …
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