# 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

FNAL

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 $\afbtt = \frac{N(\dy > 0) - N(\dy < 0)}{N(\dy > 0) + N(\dy < 0)}$ $\dy=y_{t}-y_{\bar{t}}$ $$\ttbar\rightarrow\ell\nu+jets$$: $$\ttbar\rightarrow\ell^{+}\ell^{-}+jets+\MET$$: Inclusive $$\afbtt$$ 2 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 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 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 The best fit result is $\alpha = 0.227\pm0.057$ This result is $$2\sigma$$ larger than the NNLO SM calculation 6 Comparison of the slope $$\alpha$$ of $$\afbtt$$ vs. $$|\dy|$$ from various measurements.

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