We present the measurement of the \ttbar\ cross section in the
lepton plus jets channel with $\ge 1$ and $\ge 2$ secondary vertex tags. 
We use the scalar sum of transverse energies of the event ($H_T$) to
discriminate \ttbar\ from the other backgrounds. We also use the
transverse mass of the leptonic $W$-boson ($M_T^W$) to further reduce
the Non-W backgrounds.
We use a combination of data and Monte Carlo to estimate the
backgrounds from electroweak processes, single top, fake leptons, $W$+ Light Flavor fake tags,
and real $W$+ Heavy Flavor production.

We obtain a value of $\sigma_{\ge 1}  =  8.7 ^{+0.9}_{-0.9} (stat) ^{+1.2}_{-0.9} (sys)$ pb
for the $\ge 1$ tag cross section, and $\sigma_{\ge 2}  = 8.7 ^{+1.8}_{-1.6} (stat) ^{+1.9}_{-1.3} (sys)$ pb
for the $\ge 2$ tag cross section.

%For the unoptimized measurement, we measure a $\ttbar$ cross section of
%$\sigma_{\ge 1} =  8.9 ^{+1.0}_{-0.9} (stat) ^{+1.3}_{-1.0} (sys)$ pb
%for the $\ge 1$ tag cross section and 
%$\sigma_{\ge 2} =  8.2 ^{+1.7}_{-1.5} (stat) ^{+2.1}_{-1.5} (sys)$ pb
%for the $\ge 2$ tag cross section.

We also present a measurement of the $\ttbar$ cross section by fitting
the $N_{jet}$ spectrum. 
We combine the $=1$ and $\ge 2$ tag cross sections to obtain
$\sigma_{t\bar{t}}= 8.9^{+0.9}_{-0.9} (stat) ^{+1.4}_{-1.3} (syst) pb$.



Posted to /cdf/pub/thesis/cdf7894_rappoccio_thesis.pdf
    http://www-cdf.fnal.gov/thesis/cdf7894_rappoccio_thesis.pdf

Posted by rappocc