Ricardo Eusebi Ricardo Eusebi Fermi National Accelerator Laboratory Fermi National Accelerator Laboratory (on behalf of the CDF and D0 collaborations) (on behalf of the CDF and D0 collaborations) Top Quark Properties Top Quark Properties results and ongoing analyses at the Tevatron results and ongoing analyses at the Tevatron Rencontres de Moriond Rencontres de Moriond QCD and High Energy Interactions QCD and High Energy Interactions March - 2008 March - 2008
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Top Quark Properties results and ongoing analyses at the Tevatron
Top Quark Properties results and ongoing analyses at the Tevatron. Ricardo Eusebi Fermi National Accelerator Laboratory (on behalf of the CDF and D0 collaborations). Rencontres de Moriond QCD and High Energy Interactions March - 2008. Top Pair Production at the Tevatron. - PowerPoint PPT Presentation
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Ricardo EusebiRicardo EusebiFermi National Accelerator LaboratoryFermi National Accelerator Laboratory
(on behalf of the CDF and D0 collaborations)(on behalf of the CDF and D0 collaborations)
Top Quark PropertiesTop Quark Properties results and ongoing analyses at the Tevatronresults and ongoing analyses at the Tevatron
Rencontres de Moriond Rencontres de Moriond QCD and High Energy InteractionsQCD and High Energy Interactions
Beyond SM models predict branching ratios up to O(10–2)…
Transverse mass:
Allowed at higher orders, but heavily
suppressed (GIM, small CKM elements)
March 11th, 2008 Ricardo Eusebi - Rencontres de Moriond 9
Top FCNC Search: ResultsTop FCNC Search: Results Events separated in three categories:
Tagged, anti-tagged and control region
World’s best limit. Improved previous limit (13.7% @ L3) by a factor of 3.5
B(tZq) < 3.7% @ 95% C.L.
March 11th, 2008 Ricardo Eusebi - Rencontres de Moriond 10
Forward-Backward Charge asymmetryForward-Backward Charge asymmetry Reconstruct the tt decay chain and get the top rapidities yt and yt
Using 0.9 fb-1, Lepton+jets channel
Theory : NLO not a good approx to SM. NLO: 3.8% to 4-5% (Rodrigo & kuhn, Bpowen, Ellis & Rainwater) NNLO: 0 to -3%( Dittmaier, Uwer, Weinzierl) Shape of asymmetry unknown!
Solution: For a model’s prediction of |y| distribution
dilution function is used to go to the particle level
Probe for new physics Example: limits on Z’ based on charge asymmetry
bf
bffb NN
NNA
Nf (NB) = # of tt events with positive (negative) tt yyy
)( 01.0)( 08.012.0 syststatAobsfb
)()(
ttppttZppf
March 11th, 2008 Ricardo Eusebi - Rencontres de Moriond 11
Search for 4Search for 4thth generation top (t’) generation top (t’) Appear in some SUSY models
Beautiful mirrors, Little Higgs Room in EWK data:
could accommodate a heavy Higgs (~500 GeV) without any other new particles
Search for generic t’Wq in lepton+jets channel
2D likelihood fit to the event HT and the reconstructed mass of ttbar-like system
Exclude t’ below 284 GeV @ 95% C.L.
March 11th, 2008 Ricardo Eusebi - Rencontres de Moriond 12
Is the Top Is the Top really the really the Standard Standard
Model Top?Model Top?
Top Properties: Other MeasurementsTop Properties: Other MeasurementsDifferential cross section
d i
dM tt
N i N i
bkg
A i LM tt
i
Top spin correlations
Top quark Width%CL 95 @ GeV 7.12top
Top pair resonancesTop-pair Production
)()(
ttppttggFGG
March 11th, 2008 Ricardo Eusebi - Rencontres de Moriond 13
Conclusions Conclusions CDF and D0 are seriously focused on exhaustive
measurements of top properties
Many more analyses ongoing B(tH+b), with H+ decaying to specific channels Top quark width Top spin correlations and more…
Exciting times : Analyses are very mature Much more data on tape
Uncertainties are beginning to shrink and more and more we are putting the SM to the test.