Measurement of the Forward Backward Asymmetry in Top Pair Production in the Dilepton Decay Channel using 5.1 fb-1

Authors

Yuji Takeuchi Yen-Chu Chen Jaroslav Antos
University of Tsukuba Academia Sinica Slovak Academy of Science

Chang-Seong Moon Youngdo Oh Hyunsoo Kim Thomas Schwarz
Seoul National University, Korea Kyungpook National University, Korea Chonbuk National University University of California, Davis


Send email to authors

Conference Note


ABSTRACT
We report on a measurement of the inclusive forward-backward asymmetry in tt production in the dilepton channel using 334 dilepton candidates collected in 5.1 fb-1 of collected data. The production angle of top is measured using the rapidity difference between top and anti-top quarks (Δyt). For the reconstructed asymmetry, without corrections:
Afb (data) = 0.14 ± 0.05stat

The measurement is corrected for backgrounds, detector acceptance, and resolution effects, which serve to bias and/or dilute the measurement. After subtracting the predicted background contribution, the and the asymmetry of the background subtracted Δyt is found to be:

Afb (data) = 0.21 ± 0.07stat ± 0.02bkg-shape

Finally, detector and acceptance effects are corrected by a fit, assuming a linear dependence of the production angle on the underlying asymmetry. The fully corrected measured asymmetry is:

Afb (corrected) = 0.42 ± 0.15stat ± 0.05syst

which is to be compared to the standard model prediction, Afb (theory) = 0.06 ± 0.01.


Figures

Δyt v.s. Δηl at parton level
Reconstructed Δηl
Reconstructed Δηl for e-e
Reconstructed Δηl for e-μ

eps

eps

eps

eps
Reconstructed Δηl for μ-μ
Reconstructed Mll Distribution
Δηl for 0 jet
Δηl for 1 jet

eps

eps

eps

eps
Δyt Resolution in MC
Δyt Distribution for Z(→ee)+2jets
Δyt Distribution for Z(→μμ)+2jets
Δyt Signal Templates

eps

eps

eps

eps
Δyt True Asym. v.s. bkg subtracted Δyt Asym.
Δyt True Asym. v.s. bkg subtracted Δ&etal Asym.
Δ&etal and Δyt Background Template
Reconstructed Δyt

eps

eps

eps

eps
Reconstructed Δyt for e-e
Reconstructed Δyt for e-μ
Reconstructed Δyt for μ-μ
Reconstructed Δyt for Mtt<450GeV

eps

eps

eps

eps
Reconstructed Δyt for Mtt>450GeV
Reconstructed Mtt
Bkg. subtracted Δyt Distribution
Bkg. subtracted Δ&etal Distribution

eps

eps

eps

eps
Reconstructed Δ&etal with Best fit ttbar Prediction
Reconstructed Δyt with Best fit ttbar Prediction
Uncertainties on Δyt True Asym.
Results

eps

eps

eps

eps


Last modified: Tue Mar 1 20:03:26 EST 2011