Veme Rencontres du Vietnam, 2004 1

TeVatron SUSY searchesTeVatron SUSY searchesinin

final states leptons and photonsfinal states leptons and photons

Vu Anh TuanLaboratoire de l’Accélérateur Linéaire, Orsay, France

forCDF and D collaborations

mSUGRA chargino and neutralino trilepton GMSB inclusive search in diphoton plus

missing ET

Veme Rencontres du Vietnam, 2004 2

SUSY@TeVatron (1/2)SUSY@TeVatron (1/2)

• R-parity conservation missing energy

mSUGRAo SUSY breaking mediated

by gravityo LSP is most likely

neutralino 01

o Mass: 1 0

2 201

GMSBo Mediated by gauge fieldso LSP is gravitinoo Phenomenology is entirely

determined by NLSP (slepton or neutralino)

• Analysis in this talk interpreted within mSUGRA or GMSB frameworks

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SUSY@TeVatron (2/2)SUSY@TeVatron (2/2)

• Squarks and gluinos– large cross-section– decay most of the time into jets plus MET– huge QCD multijets background

• Processes w/ lepton(s) and/or photon(s) in final state (e.g., chargino/neutralino production)– smaller cross-section (BR)– much lower QCD background Subject of this talk

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DD trilepton searches trilepton searches

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Chargino-neutralino searchesChargino-neutralino searches

• Very clean decay mode: trilepton plus MET

• Searches at DØ– Di-electron plus (any) lepton (e, ou )– Electron-muon plus (any) lepton– Like-sign dimuon ( )

• Optimized for mSUGRA parameters (near LEP II limit)– tan = 3, > 0, A0 = 0

– m0 = [72, 88] GeV, m1/2 = [165, 185] GeV

mass 1 0

2 [97, 114] GeV

mass slepton 1 enhance leptonic

decay BR 0.2-0.4 pb

• Integrated luminosity 150-175 pb-1

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eel (1/2)eel (1/2)

Signal

• DY reduction (ee) < 2.8– MET > 20 GeV

• Top pair veto: jet veto• W+ (ee)

– Require hits in the tracker innermost layers

• Third lepton: an isolated track present , pT > 3 GeV– Include e, and

(even -hadronic decays)

• Backgrounds: Z/DY, W+, diboson, Z/DY , top pair• 2 electrons: isolated, ET > 12(8) GeV, || < 1.1(3.0)• Z veto: keep M(ee) in [15, 60] GeV

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eel (2/2)eel (2/2)

• To optimize signal selection– Use the product of MET

and track pT Final cut

METpT(track) > 250 GeV2

• Observed: 1 event• Expect:

– 0.27 background event– 0.8-1.6 events from SUSY

• Remaining DY background has low MET and track pT

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eel l

Before track pT > 3 GeV cut

• Background:– Z/DY : dominant– WW, WZ, ZZ, top pair– W+j/, QCD

• e: isolated, ET > 12 GeV, pT > 8 GeV

• MET > 15 GeV Similar Z, W+ and top pair

vetoes as in eel analysis• Same isolated track (pT > 3

GeV) requirement• Observed: 0 event• Expect:

– 0.54 background events– 0.63-0.93 events from SUSY

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Like-sign dimuonLike-sign dimuon

• Backgrounds– b/c pairs (dominant)– W+jets, top pair– Charge sign-flip: Z/DY

isolated, pT > 5 GeV• bb/cc estimated from data

– Calibrated from QCD-dominated region (one µ nearly “isolated”, (µµ) > 2.7)

• Charge sign-flip: from MC and cross-checked w/ data

• Cuts– µ pT > 11(5) GeV, both

isolated, (µµ) < 2.7– Z veto, MET > 15 GeV– LS mass (µµ) < 80 GeV

• Observed: 1 events• Expect:

• 0.13 background events• 0.2-0.4 events from SUSY

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Combined trileptonCombined trilepton

• Gain better sensitivity• See 3 events from data,

expect 3.4 from SM background

• Set a 95% CL limit on trilepton cross-section– Significant improvement

over Run I– Approaching mSUGRA

sensitivity region• Result interpreted within

mSUGRA framework– Can be used to constrain

other models with similar mass hierarchy

Channel Data Background

e + e + l 1 0.27 0.42 0.02

e + 1 2.49 0.37 0.18

e + + l 0 0.54 0.24 0.04

+ 1 0.13 0.06 0.02

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CDF and DCDF and D inclusive diphoton search inclusive diphoton search

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Inclusive diphoton search (1/3)Inclusive diphoton search (1/3)

• In GMSB, neutralino could be NLSP– Assume short lifetime decays well inside detector

• SUSY particles decay down to neutralino into gravitino and photon

quark

Signature: two photons plus MET in final state

quark

SUSY production

neutralino

gravitino

gamma

neutralino

gravitino

gamma

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Diphoton search (2/3)Diphoton search (2/3)

• Background– QCD plus photon or jet fake photon (dominant)– Electron fake photon: Z/DY, W+ e+

• QCD: estimated from data– at least one EM cluster fails

standard ID cut– QCD dominated at low MET

(<20(15) GeV) normalized to predict contribution at high MET

• e: from data using identified e and

scaled by (e) fake rate

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Diphoton search (3/3)Diphoton search (3/3)

• Two photons ET > 13(20) GeV, || < 1.0(1.1)• MET > 45(40) GeV• CDF: 202 pb-1, D: 185 pb-1

• Parameters- N = 1, Mmessenger = 2

- µ > 0

- tan = 15 (CDF), 5 (D - Snowmass slope)

• Signal dominated by chargino-neutralino production

• Observed: 0 (CDF), 1 (D) events

• SM background: 0.6 (CDF), 2.5 (D) events

Lower limit on neutralino mass

CDF: 93 GeV D: 105 GeV (beyond LEP!)

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ConclusionConclusion

• CDF and DØ produce solid physics results based on up to 200 pb-1 of luminosity

• Limits exceed Run I– mSUGRA: Trilepton

analysis of chargino and neutralino

– GMSB: inclusive diphoton

• TeVatron luminosity increases steadily

• New results coming out soon!

1.00E+32