Search for SUSY at the Tevatron

Vishnu V. Zutshi

Northern Illinois University

for the

CDF and D Collaborations

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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

qq

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 …….