TeVatron SUSY searches in final states leptons and photons

1
TeVatron SUSY searchesinfinal states leptons
and photons

• mSUGRA chargino and neutralino trilepton
• GMSB inclusive search in diphoton plus missing ET

• Vu Anh Tuan
• Laboratoire de lAccélérateur Linéaire, Orsay,
  France
• for
• CDF and D? collaborations

2
SUSY_at_TeVatron (1/2)

• Analysis in this talk interpreted within mSUGRA
  or GMSB frameworks

• R-parity conservation ? missing energy

3
SUSY_at_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

4
D? trilepton searches
5
Chargino-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, ? gt 0, A0 0
• m0 72, 88 GeV, m1/2 165, 185 GeV
• mass ??1 ? ?02 ? 97, 114 GeV
• mass slepton ? ??1 ? enhance leptonic decay
• ??BR ? 0.2-0.4 pb
• Integrated luminosity 150-175 pb-1

6
eel (1/2)

• Backgrounds Z/DY, W?, diboson, Z/DY ? ??, top
  pair
• 2 electrons isolated, ET gt 12(8) GeV, ? lt
  1.1(3.0)
• Z veto keep M(ee) in 15, 60 GeV

• DY reduction
• ??(ee) lt 2.8
• MET gt 20 GeV
• Top pair veto jet veto
• W ? (??ee)
• Require hits in the tracker innermost layers
• Third lepton an isolated track present , pT gt 3
  GeV
• Include e, ? and ? (even ?-hadronic decays)

Signal
7
eel (2/2)

• Remaining DY background has low MET and track pT

• To optimize signal selection
• Use the product of MET and track pT
• Final cut
• MET?pT(track) gt 250 GeV2
• Observed 1 event
• Expect
• 0.27 background event
• 0.8-1.6 events from SUSY

8
e?l

• Background
• Z/DY ? ?? dominant
• WW, WZ, ZZ, top pair
• Wj/?, QCD
• e? isolated, ET gt 12 GeV, pT gt 8 GeV
• MET gt 15 GeV
• Similar Z, W? and top pair vetoes as in eel
  analysis
• Same isolated track (pT gt 3 GeV) requirement
• Observed 0 event
• Expect
• 0.54 background events
• 0.63-0.93 events from SUSY

Before track pT gt 3 GeV cut
9
Like-sign dimuon

• Backgrounds
• b/c pairs (dominant)
• Wjets, top pair
• Charge sign-flip Z/DY
• ?? ?? isolated, pT gt 5 GeV
• bb/cc estimated from data
• Calibrated from QCD-dominated region (one µ
  nearly isolated, ??(µµ) gt 2.7)
• Charge sign-flip from MC and cross-checked w/
  data
• Cuts
• µ pT gt 11(5) GeV, both isolated, ??(µµ) lt 2.7
• Z veto, MET gt 15 GeV
• LS mass (µ?µ?) lt 80 GeV

• Observed 1 events
• Expect
• 0.13 background events
• 0.2-0.4 events from SUSY

10
Combined 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

11
CDF and D? inclusive diphoton search
12
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

13
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 (lt20(15) GeV) ?
  normalized to predict contribution at high MET
• e? from data
• using identified e? and scaled by (e??) fake rate

14
Diphoton search (3/3)

• Two photons ET gt 13(20) GeV, ? lt 1.0(1.1)
• MET gt 45(40) GeV
• CDF 202 pb-1, D? 185 pb-1

• Parameters
• N 1, Mmessenger 2?
• µ gt 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!)
15
Conclusion

• 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!

1.00E32