Recent Results on New Phenomena from CDF PASCOS

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Recent Results on New Phenomena from CDFPASCOS
04, August 16-22Boston, MA

• Dmitri Tsybychev on behalf of CDF Collaboration
• U. Florida/SUNY at Stony Brook

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Outline

• Introduction
• SM and BSM Higgs searches
• Supersymmetry searches
• Di-Lepton and Di-Photon searches
• Other searches
• Summary

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Major Challenges

• Predicted new physics cross-sections are within
  the reach of the Tevatron
• Cross-sections are strongly dependent on particle
  masses, less so on model parameters
• Backgrounds can be orders of magnitude larger
  than the signal

• Challenge for the experimentalists HOW !
• Production rates, luminosity,
• Trigger (keep 1 out of 24000 collisions)
• Detection efficiency
• Suppress background
• Differentiate signal and background

Higgs LQ LED
Use combination of data/simulation to devise
cuts, predict backgrounds/estimate acceptances
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Searches for New Phenomena

• Models
• Higgs
• MSSM
• Extra Dimensions
• Leptoquarks
• Compositeness
• W, Z

• Experimental signatures
• g
• e, m (generically lepton)
• t
• Jets (quarks and gluons)
• Heavy Flavor tagging (b,c)
• Missing transverse energy

• Use both
  signature/model based searches
  
• Sensitivity to many models
  Best sensitivity for given model
• Unbiased
• Investigate all possible
  signatures
• Report results on searches with Run II
  data (L200 pb-1)
• Coming soon first results in 500 pb-1 dataset

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SM Higgs

• Higgs boson is crucial to our understanding of
  EWSB
• For mh lt 135 GeV/c2
• h?bb dominates
• gg?h suffers from large SM background

• For mh gt 135 GeV/c2
• h?WW dominates
• Can look for gg?h ?WW,ZZ
• Low SM background
• Many additional Higgs bosons in models beyond SM,
  some of them have higher sensitivity

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SM Higgs

• For Mh gt 135 GeV/c2 h?WW?l?l? (e?)
• Require 2 isolated opposite sign leptons (pTgt20
  GeV/c)
• Missing ET gt 25 GeV
• No jets
• Z removal
• Dilepton ivariant Mass Mlllt ½Mh

• Mh 160 170 180
  
• WW 4.5 0.5 5.4 0.6 6.5 0.8
  
• Other 1.3 0.4 1.9 0.5 2.4 0.7
• Data 3 7
  8
• Expected signal 0.2
• Extract 95 CL limit using likelihood fit
• To angular distribution

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SM Higgs

• Golden mode hW?bbl? (e?)
• Require exactly 1 lepton (pTgt20 GeV/c)
• Missing ETgt20 GeV
• Excatly 2 jets ( 1 or more SVX b-tag)
• Need highly efficient, pure b-tagging
• ?b 53 (in t-tbar events)
• ?c 3 ?uds,g lt 1
• Need excellent di-jet resolution
• currently 17 ? 10 achievable

• Expect 60.5 4.4 background events
• 25.2 3.2 W hf
• Observe 62
• Signal 0.7 for Mh 115 GeV/c2
• Use di-jet mass spectrum to exctract 95 CL

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SM Higgs

• Still order of magnitude higher than SM
  prediction
• Combine with other channels
• hZ?bb??
• Need more data

• Interesting for other EWSB mechanisms
• Technicolor
• Results depend on m(?T) and m(?T)

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MSSM Higgs

• SUSY new type of symmetry
• Fermions ? Bosons
• Many models
• In MSSM 5 Higgs particles
• CP-even h,H
• CP-odd A
• Charged H
• tan? - ratio of VEV of scalar fields
• For neutral Higgs couplings to third generation
  can be enhanced at high tan?
• A?bb is tough - consider A???

• Narrow jet of track/energy for hadronic ?-id
• Isolated from nearby tracks/energy
• Add reconstructed ?0

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MSSM Higgs

• Select events with one ??l (e?) and one hadronic
  ? deacy
• HT gt 50 GeV (scalar sum of ? momenta and missing
  ET)
• Missing ET should not point in opposite direction
  to ? decay products

• Mass resolution worse at higher masses
• Use binned likelihood fit to mass spectrum set
  95 CL limit
• Limit is order of magnitude higher than
  prediction (tan?)

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Search for H

• H predicted in models that contain Higgs
  triplets
• Left-Right (LR) symmetric models
• SUSY LR models low mass (100 GeV 1 TeV)
• Partial decay width
• hll Yukawa coupling, free parameter, determines
  
• H stable or prompt

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Search for H

• Stable H
• Two heavily ionized tracks in tracking chamber
• Muon-like in muon chambers
• MIP-like in calorimeter
• Require a muon with pTgt20 GeV/c and another
  track with pTgt20 GeV/c
• 0 events observed

• Prompt H
• Two same sign leptons (ee,e?,??)
• Very small SM background
• Search for a lepton pair in mass window of
  ?10M(H) (3s detector resolution)
• 0 events observed

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Sbottom from Gluino Decay

• 3rd generation squarks could be light
• Large top mass ? light stop
• At large tan? ? light sbottom
• If gluino is light enough the pair production at
  Tevatron is large
• Assume R-parity conservation
• LSP stable
• Good candidate for dark matter
• Branching ratio strongly depends on sparticle
  masses
• Assume
• Assume m(gluino) gt m(b1) gt m(?10), m(t) m(?1
  ) gt m(b1)
• BR (b1 ? b?10) 100

4 b-jets Missing ET
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Sbottom from Gluino Decay

• Event selection
• Missing ET gt 80 GeV
• 3 jets ( 1 or 2 SVX b-tags)
• Missing ET direction is not
• collinear with jets
• No isolated leptons

• No excess observed in data
• Large exclusion in sbottom-gluino plane

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Searches in Di-Leptons

• Looked at di-lepton invariant mass and angular
  distributions to search for new phenomena
• Select events with 2 high pT leptons
• Many model predict enhancement at higher mass
• Extra Dimensions, Z, Technicolor
• Expect mass peaks, enhancement in the spectra
• Data in good agreement with SM predictions
• Extract limits on many new models from the spectra

ee
??
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Search for Z in ?? channel

• Look in high mass region for
• new physics
• M (Missing-ET,?,?) gt 120 GeV
• Missing-ET gt 15 GeV
• ?f(Missing-ET, ?) gt 30º

• Expect 2.830.39 events, see 4
• Exclude Zlt394 GeV/c2 95 CL
• (Z with SM couplings)

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Extra Dimensions
d?/dM (pb/GeV)

• The large gap between EW and Planck scales is
  assumed to be due to the extra dimensions
• Models predict different geometry, number of
  extra dimensions
• Only Graviton propagates in the ED, SM particles
  are trapped in
• 3-D brane
• The gap is narrowed by reducing the effective
  fundamental scale to 1 TeV
• In the compactified ED, gravity expands into a
  series of Kaluza-Klein (KK) states
• For example
• Randall-Sundrum ED Model
• 1 highly curved extra dimension
• Gravity localized in the ED
• Scale of physical phenomena on the TeV-brane is
  specified by the exponential warp factor
• ?? MPle-kRc?
• New parameters
• First graviton excitation mass m1
• Ratio k/MPl

10-2 10-4 10-6 10-8
K/MPl
1 0.7 0.5 0.3 0.2 0.1
Tevatron 700 GeV KK graviton
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Di-Photon

• Search for high mass ?? events in 345 pb-1
• 2 isolated ?
• ETgt15 GeV
• In addition to ee, ?? channels

• Can combine ??, ee, ?? channels to set a more
  stringent limit
• qq channel in progress

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Leptoquarks at the Tevatron

• Pair produced at the Tevatron
• Assumed to couple to leptons and quarks within
  the same generation
• b branching ratio to charged lepton
• Decay
• Experimental signatures
• Missing ET 2 jets
• 1 isolated lepton
• Missing ET 2 jets
• 2 isolated leptons 2 jets

• Remarkable symmetry between quarks and leptons in
  SM ? new symmetry
• Leptoquarks are predicted in GUT models, SUSY
  (with RPV), Technicolor and Compositeness
• Connect leptons and quarks in the SM
• Leptoquarks are color triplet bosons (scalar or
  vector) with lepton number
• and fractional electric charge

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1st and 2nd Generation Leptoquarks

• Generation ? Mass Limit(GeV/C2)
• 1 1 gt230
• 0.5 gt176 (182
  Run I)
• 0 gt117
• 2 1 gt241
• 0.5 in progress
• 0 gt124 (Run
  I)

LQ1LQ1 ? eejj
LQ2LQ2 ? ??jj
m(LQ) gt 230 GeV/c2 95 CL
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Magnetic Monopole

• Produced in pairs in Drell-Yan like processes
• Search for highly ionizing tracks in
  Time-of-Flight system and tracking chamber
• Dedicated monopole trigger based on TOF
• 0 events observed

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Summary

• Good sensitivity beyond existing limits for new
  physics at Tevatron
• Have now 5x more data than in Run I
• Many more analyses in progress
• Stay tuned
• Visit CDF physics result web page for new results
• http//www-cdf.fnal.gov/physics/physics.html
• Can address key SM question before LHC
• Much excitement at both Tevatron experiments for
  physics beyond SM
• Will be more exciting if see some evidence for
  new physics