Exploring New Phenomena at CDF

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Exploring New Phenomena at CDF

• Jane Nachtman (Fermilab)
• for the CDF collaboration

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Objective

• This workshop is about bringing theorists and
  experimentalists together to focus on maximizing
  the Tevatrons discovery potential
• The experimental talks will briefly summarize
  searches for new physics at CDF and D0
• To help us think about what is possible and where
  we should go from here
• Looking for theorists input!
• We split the signatures
• CDF photons, jets MET, hi-pt dileptons
• D0 leptonsjets, multi-leptons, long-lived
  signatures

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Overview of my talk

• Brief CDF and Tevatron intro
• CDF searches
• Signature-based, then applied to models
• Photons
• Applied to GMSB, Extra Dimensions
• Hi-pt dileptons
• Z, G
• METjet(s)
• SUSY, LED
• Global, signature-based search of all CDF hi-pt
  data (VistaSleuth)

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CDF Detector
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Tevatron
The Tevatrons performance is better than ever!!
Almost 2 fb-1 delivered, 1.6 fb-1 recorded (
0.95 1.2 fb-1 for analysis, depending on which
subsystems are used) 4-8 fb-1 by 2009
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Signature-based searches at CDF

• Philosophy models come and go, but the data
  should stand on its own
• Design simple searches
• No optimization for models ? no sophisticated
  cuts
• Attempt to provide general result for theoretical
  input
• Basic result N expected from SM, N observed
• Study kinematic distributions
• Publish acceptance functions plug in your own
  model
• Drawback may not provide maximal sensitivity to
  a particular model
• But may point us in the right direction to look
  further

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Signature-based searches for photonX

• Inspired by Run I hints
• eeggMET event
• Excess in leptonphotonMET (16 obs, 7.6 /- 0.7
  exp)
• Theoretical models suggest these signatures (eg
  GMSB)
• Mix-n-match photons, leptons (e,m,t), MET,
  jets,b-jets

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Search for photonleptonX

• 2 channels
• Photon lepton(e,m) MET
• Photon lepton lepton X
• Look for high-pt leptons, photons, high MET
  (reduce fakes, SM backgrounds)
• In 930 pb-1 of data
• e?MET ??MET l?MET
• SM 94?8 54?7 148?13
• Data 96 67 163
• ee?X ???X ll?X
• SM 39?5 26?3 65?8
• Data 53 21 74

SM is W/Z gamma, Wfake No events with extra
photons, leptons observed
SM is W/Z gamma, Wfake No events with extra
photons, leptons,MET observed No em
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Check kinematics in lgammaMET
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Diphoton X searches

• X e,m,g,MET
• Backgrounds evaluated from data
• Use sidebands loose photons not passing signal
  photon selection
• Dataset 1 1.2 fb-1
• ggX, X SM Nobs
• e 3.8 /- 0.5 1
• m 0.7 /- 0.1 0
• MET 116 /- 24 126
• g 2.2 /- 0.7 4

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Kinematics in ??X channels
Control region
Signal region
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High-mass diphotons

• high ET (gt15) isolated diphoton resonance
• Background QCD diphotons (simulation), jets
  (from data)

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Long-lived Exotic particles

• D0 talk will cover more in detail, just one
  photon-based search here
• Several models predict long-lived particles
  charged or neutral, decaying inside or outside
  detector
• Charged look like slow muon (new CDF results
  soon) or delayed jet
• Neutral
• decay inside detector delayed photons ?CDF
  analysis
• decay outside detector photon MET ?planned
  analysis

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Delayed Photon Analysis

• Relies on EM calorimeter timing detector

Measure photon arrival time?
background
signal
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Search for Delayed Photons
Interpret in GMSB
No new physics found here, so far
signal region
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Signature-based searches for dileptons X at CDF

• Look for excess above SM prediction in dilepton
  X (X photon, lepton, b-jet, HT, Missing ET
  dileptons can be same-sign or opposite-sign)
• Set cuts on first 1/3rd of dataset,apply to
  larger dataset
• can be further applied to many models e.g. heavy
  quarks as first example

Dilepton (ee, mm, em) high HT
Good agreement in HTlt200 control region.
No excess, but one event at HT900!
HT scalar sum of electron and jet ET, muon pT,
missing ET
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High mass dileptons

• High ET electrons, optimized to look for
  high-mass resonances (150-950 GeV)
• Applied to spin-1 Z and spin-2 RS Graviton

19 pes have 2E-3
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Set limits on SM-like Z

• Combine limits with diphoton on coupling vs
  graviton mass in RS model

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Search for Massive Resonances Decaying to ZZ ?eeee

• Spectacular signature!!
• Model RS Gravitons can decay to ZZ, sxBr292fb
  (0.66 events expected in 2 fb-1 not yet
  sensitive)

Signal region M(eeee) 500-1000 GeV
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Like-Sign dileptons

• Signature-based search
• Currently chargino-neutralino production

Basic selection expect 34/-4, see 44 Tight
selection expect 8 /- 1, see 13
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MET Jets

• Signature monojet events
• Model LED (ADD)
• Graviton production leads to excess (not
  resonance)

Set limits on MD vs N extra dimensions
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MET jets in SUSY

• Search for squarks/gluinos in MET jets

Add flavor tagging for stop/sbottom
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Vista/Sleuth the ultimate signature-based search

• Algorithm to look at Tevatron data globally
• Because new physics will probably not show up
  where we are expecting it
• Look in hundreds of final states simultaneously
• Vista look at bulk distributions, find
  compatibility with SM (chi-square fit)
• Sleuth look in hi-pt tails
• Flag a final state as interesting
• Show us where to look in more detail
• Further steps Quaero and Bardto interpret new
  physics

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summary

• Tevatron searches are going at full steam
• Lots of analyses ongoing, new and interesting
  results coming out
• No new physics yet, but we remain hopeful
• Need to focus our efforts for the full Tevatron
  dataset
• What can we learn from what weve already done,
  to plan for the future?
• Weve tried to cover as much as possible, but are
  we overlooking important signatures, models?
• Theoretical guidance for our program of Searches
  for New Physics

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Backup Slides
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SM and Other Backgrounds
SM Collisions

• 4 sources, all estimated from data
• Collision photons from SM
• Right vertex
• Wrong vertex
• Non-collision look-like photons
• Beam Halo
• Cosmics

Beam Halo
Signal Monte Carlo
Cosmics
How do I know how each background looks like?
Can not use photons.
Signal (Blinded) Region
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Highest Mass Diphoton Event (604 GeV/c2)
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Highest Mass Diphoton Event
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Top dilepton event at HT900?
Jets 216 GeV (b-tag) 199 GeV 156 GeV 15 GeV

• Leptons
• e 28 GeV,
• m 159 GeV

MET 90 GeV