Search for heavy quarks in same-sign dileptons

Summer 2009: 2.7 fb-1

M. Hickman1, D. Whiteson1, M. Wilson2, D. Berge3

1 University of California, Irvine
2 SLAC
3 CERN

CDF Collaboration

E-mail authors

This analysis has been updated and submitted to PRL: 0912.1057.


We report a search for a heavy fourth-generation down-type quark ($b'$) which decays with 100\% branching ratio $b' \rightarrow tW$, giving a significant number of same-charge dilepton events. In addition, we search for exotic top partners $(B,T_{5/3})$ which have similar decays. We select events with two same-charge leptons, missing transverse energy, at least two jets and a positive $b$-tag.

In 2.7 fb-1 of Run II data, we exclude a b' (or B) with mass less than 338 GeV, and a T5/3 with mass less than 365 GeV at 95% confidence level.

Documentation

Tables and Plots

Description jpg pdf/eps
(Paper version)
Best fit in jet multiplicity
pdf
(Paper version)
MET in same-sign leptons
pdf
(Paper version)
Sensitivity
pdf
Validation of Z in opposite sign-leptons pdf /eps
Validation of top quark pairs in opposite-sign leptons, missing energy and a btag pdf /eps
Dilepton invariant mass in same-charge dilepton events with two electrons pdf /eps
Dilepton invariant mass in same-charge dilepton events with an electron and a muon pdf /eps
Dilepton invariant mass in same-charge dilepton events with two muons pdf /eps
Dilepton invariant mass in all same-charge dilepton events pdf /eps
Missing transverse energy in same-charge dileptons pdf /eps
View of tracker for electron-muon 5-jet event pdf /eps
LEGO view of calorimeter for electron-muon 5-jet event pdf /eps
Selected objects in electron-muon 5-jet event
ObjectPtEtaPhi
Electron73.1 GeV0.99-1.02
Muon20.6 GeV0.98-2.63
Jet59.5 GeV1.272.71
bJet42.3 GeV0.87-2.63
Jet38.5 GeV1.360.44
Jet33.4 GeV1.670.02
Jet24.1 GeV0.801.96
MET26.5 GeV---1.44
Invariant mass of object pairs in electron-muon 5-jet event
Object 1Object 2Mass(1,2) [GeV/c^2]
ElectronMuon55.9
Jet 1Jet 249.9
Jet 1Jet 383.1
Jet 1Jet 479.2
Jet 1Jet 547.9
Jet 2Jet 386.9
Jet 2Jet 488.7
Jet 2Jet 533.0
Jet 3Jet 418.7
Jet 3Jet 545.4
Jet 4Jet 553.3
View of tracker for muon-muon 3-jet event pdf /eps
LEGO view of calorimeter for muon-muon 3-jet event pdf /eps
Selected objets in muon-muon 3-jet event
ObjectPtEtaPhi
Muon79.7 GeV0.33-0.85
Muon30.6 GeV-0.572.85
Jet77.5 GeV-0.932.44
Jet40.1 GeV-0.662.92
bJet25.2 GeV-0.312.41
MET86.6 GeV----0.21
Invariant mass of object pairs in muon-muon 3-jet event
Object 1Object 2Mass(1,2) [GeV/c^2]
Muon 1Muon 2105.5
Jet 1Jet 230.5
Jet 1Jet 327.8
Jet 2Jet 319.6
Daniel Whiteson
Last modified: April 2009