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Combination of \(\afbtt\) at CDF
Authors
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
FNAL
Joey Huston
Michigan State University
Dilepton Final State
Ziqing Hong, Dave Toback, and Jon S. Wilson
Texas A&M University
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 |
\[\afbtt = \frac{N(\dy > 0) - N(\dy < 0)}{N(\dy > 0) + N(\dy < 0)}\]
\[\dy=y_{t}-y_{\bar{t}}\]
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\(\ttbar\rightarrow\ell\nu+jets\):
\(\ttbar\rightarrow\ell^{+}\ell^{-}+jets+\MET\):
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Inclusive \(\afbtt\)
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| 2 |
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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.
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| 3 |
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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%.
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Differential \(\afbtt\) vs. \(|\dy|\)
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| 4 |
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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.
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| 5 |
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The best fit result is
\[\alpha = 0.227\pm0.057\]
This result is \(2\sigma\) larger than the NNLO SM calculation
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| 6 |
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Comparison of the slope \(\alpha\) of \(\afbtt\) vs. \(|\dy|\) from various measurements.
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![\[\afbtt = \frac{N(\dy > 0) - N(\dy < 0)}{N(\dy > 0) + N(\dy < 0)}\] \[\dy=y_{t}-y_{\bar{t}}\]](images/AFBtt.png){kind=link}