search for susy at the tevatron
DESCRIPTION
Search for SUSY at the Tevatron. Vishnu V. Zutshi Northern Illinois University for the CDF and D Collaborations. Outline. MSSM Stop search (CDF) mSUGRA Single electron channel search (D ) RPV Decays of stop pair (CDF) di-muon channel, pair & resonant prod. (D ) - PowerPoint PPT PresentationTRANSCRIPT
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Search for SUSY at the Tevatron
Vishnu V. Zutshi
Northern Illinois University
for the
CDF and D Collaborations
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ICHEP02, 25th July 2002 V. Zutshi, Northern Illinois University 2
Outline
• MSSM Stop search (CDF)
• mSUGRA Single electron channel search (D)
• RPV Decays of stop pair (CDF) di-muon channel, pair & resonant prod. (D)
• GMSB Light gravitino search (CDF) di-photon channel search (D)
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Run1 CDF and D Detectors
DØ
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Run 2 CDF and D Detectors
silicon detector, c.o.t., tile plugand forward calorimeters……
sci-fi central tracker,silicon detector2T magnet, preshower detectors…..
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Stop Search
Final state: 2 leptons+jets+MET
Drell-Yan, heavy quark pair prod.,QCD fakes, diboson production
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Stop Search (II)
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(m)SUGRA models
• SUSY breaking is communicated to the physical sector by gravitational interactions
• GUT scale parameters + RGE’s low-scale phenomenology
M0 = 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
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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,t tCuts: Et
e >20 GeV,Etj >14 GeV
( 4), no isolated muons, MET > 25 GeVL = 92.7 pb-1
Observed events = 72Expected background = 80 ± 10
DØ
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Single Electron Channel
DØ
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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
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Decays of Stop Pair
CDF Run IIa proj. ~ mt
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Pair Production: di-muon channel
01
~~
c
s
'222
Final state: 2 + 4jets
•Bckg: Drell-Yan, t t, 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
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Pair Production: di-muon channel
DØ
Run IIa projection
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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: t t, Z+2jets, WW+jetsCuts: pT
>20 GeV, pTjets >20 GeV,
ST >50 GeV, R(-jet) > 0.5L = 94 ± 5 pb-1 Observed events = 5
Expected bckg = 5.34 ± 0.07D
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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
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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
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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
CDFRun IIa proj. ~ 270 GeV
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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
)~
)(~
(X~~ 0 GGpp ii
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Di-photon Channel (II)
DRun IIa proj. ~ 300 GeV
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Di-photon Channel (III)
Run II
MET
D Run IIpreliminary
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Summary
• Comprehensive searches for SUSY have been carried out at the Tevatron exploiting the Run 1 data to the fullest.
• A new era is beginning …….