\(\newcommand{\ttbar}{\rm{t\bar{t}}}\) \(\newcommand{\DYtt }{\rm{DY\rightarrow\tau\tau}}\) \(\newcommand{\DYeemm }{\rm{DY\rightarrow ee/\mu\mu}}\) \(\newcommand{\gev}{\rm{GeV}}\) \(\newcommand{\pt}{p_{T}}\) \(\newcommand{\mt}{m_{T}}\) \(\newcommand{\Ht}{H_T}\) \(\newcommand{\MET}{\mbox{$E\kern-0.50em\raise0.10ex\hbox{/}_{T}$}}\) \(\newcommand{\met}{\mbox{$E\kern-0.50em\raise0.10ex\hbox{/}_{T}$}}\) \(\newcommand{\sys}{\text{syst.}}\) \(\newcommand{\syst}{\text{syst.}}\) \(\newcommand{\stat}{\text{stat.}}\) \(\newcommand{\et}{E_{\text{T}}}\) \(\newcommand{\Et}{E_{\text{T}}}\) \(\newcommand{\mll}{\rm{m_{ll}}}\) \(\newcommand{\mtt}{m_{\ttbar}}\) \(\newcommand{\afb}{A_{\text{FB}}}\) \(\newcommand{\AFB}{A_{\text{FB}}}\) \(\newcommand{\qeta}{q_{\ell}\eta_{\ell}}\) \(\newcommand{\deta}{\Delta\eta_{\ell}}\) \(\newcommand{\afblep}{A_{\text{FB}}^{\ell}}\) \(\newcommand{\afbdeta}{A_{\text{FB}}^{\ell\ell}}\) \(\newcommand{\afbtt}{A_{\text{FB}}^{\ttbar}}\) \(\newcommand{\fbm}{\rm{fb}^{-1}}\) \(\newcommand{\atanh}{a\cdot\tanh(\frac{1}{2}\qeta)}\) \(\newcommand{\atanhdeta}{a\cdot\tanh(\frac{1}{2}\deta)}\) \(\newcommand{\dy}{\Delta y_{t}}\) \(\newcommand{\pztt}{p_{z, \ttbar}}\) \(\newcommand{\pttt}{p_{T, \ttbar}}\) \(\newcommand{\Mtt}{m_{\ttbar}}\)

Combination of \(\afbtt\) at CDF


Lepton+Jets Final State

Dan Amidei, Myron Campbell, Ryan Edgar, Dave Mietlicki, Monica Tecchio, Jon S. Wilson, and Tom Wright

University of Michigan

Thomas A Schwarz


Joey Huston

Michigan State University

Dilepton Final State

Ziqing Hong, Dave Toback, and Jon S. Wilson

Texas A&M University

Public note: CDF11161

We present a combination of the measurements of the \(\afbtt\) from CDF with lepton+jets and dilepton final states using the full dataset collected by the CDF II detector. The improved measurement is \(\afbtt = 0.160\pm0.045\). The combined result is consistent with the NNLO SM calculation at \(\afbtt = 0.095 \pm 0.007\). The differential \(\afbtt\) as a function of \(|\dy|\) in the two final states are also combined with a simultaneous fit, yielding a result of \(\alpha=0.227\pm0.057\), which is \(2\sigma\) higher than the NNLO SM calculation.

1 \[\afbtt = \frac{N(\dy > 0) - N(\dy < 0)}{N(\dy > 0) + N(\dy < 0)}\] \[\dy=y_{t}-y_{\bar{t}}\]



Inclusive \(\afbtt\)
2 Uncertainty correlations

Table of uncertainties of \(\afbtt\) measurement with the lepton+jets and the dilepton final states.

In the column of correlation, "0" indicates no correlation and "1" indicates fully positive correlation.

3 Figure of comparison

The combined \(\afbtt\):

\[\afbtt = 0.160\pm0.045\]

The weight of the lepton+jets result is 91%, and the weight of the dilepton result is 9%.

The correlation between the two results is 10%.

Differential \(\afbtt\) vs. \(|\dy|\)
4 Figure of slope comparison

The best fit of \(\afbtt=\alpha\cdot|\dy|\) with measurements from both lepton+jets and dilepton final states. All correlations are taken into account. The bin centroids, differential \(\afbtt\), as well as eigenvalues and eigenvectors of the covariance matrix is shown.

5 Figure of slope comparison

The best fit result is

\[\alpha = 0.227\pm0.057\]

This result is \(2\sigma\) larger than the NNLO SM calculation

6 Figure of slope comparison

Comparison of the slope \(\alpha\) of \(\afbtt\) vs. \(|\dy|\) from various measurements.

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