Dear colleagues,

in order to facilitate easy access to my thesis for anyone interested I'm
making it available as a CDF note. The abstract reads:

This thesis presents a search for top quark pair production via the process 
p pbar -> t tbar + X -> W+W- b bbar + X -> (l+ nu_l)(l- nubar_l) b bbar + X, 
where l is either e, mu, or tau. Using a sample of 109+-7 pb of ppbar collisons
at sqrt{s}=1.8 TeV collected by the CDF detector at the Fermilab Tevatron we
find a clear signal for ttbar production in the ee, mumu, and emu dilepton
channels. We observe 9 events where we expect 3.9+-0.7 ttbar events (based on
the theoretical production cross section)  and 2.1+-0.4 background events. The
ttbar production cross section measured from this channel is 
sigma_{ttbar}=8.5^{+4.1}_{-3.3}(stat)^{+1.6}_{-0.8} (syst) pb. Using a method
developed in this thesis to identify hadronically decaying tau leptons we also
search for etau and mutau dilepton events from t tbar production and decay. We
observe 4 events and expect 2.5+-0.4 background events. In 3 of the 4 events at
least one jet is tagged as due to a b quark decay. We expect 0.28+-0.02 tagged
events from background processes. Based on the 4 tau dilepton events we
calculate the  ttbar production cross section to be 
sigma_{t tbar } = 10.2^{+16.3}_{-10.2}(stat)+-1.6(syst) pb. The kinematics 
and topology of the candidate events are generally consistent with the
expectations, with two exceptions. Five of the 14 candidate events have
unusually large missing transverse energy. One emu event contains an electron
with very high Et (182 GeV) and an additional high--Et (23 GeV) isolated
positron. In 109 pb we expect (2.4+-0.9)x10^{-6} such  ``trilepton" events from
t tbar production and decay.

Enjoy,

Marcus 


Posted to $CDF_PUB/cdf4280_thesis_dil_e_mu_tau.ps
    http://www-cdf.fnal.gov/cdfnotes/cdf4280_thesis_dil_e_mu_tau.ps

Posted by hohlmann@fnald