Measurement of the average time-integrated mixing probability of
b-flavored mesons
Primary authors: Paolo Giromini, Fabio Happacher, Fotios Ptochos
We use a fit to the impact parameters of muon pairs reconstructed in the silicon tracker to estimate the number of like-sign (LS) and opposite-sign (OS)
muon pairs arising from double semileptonic decays of b and b
hadrons pair-produced at the Fermilab Tevatron collider.
The data sample was collected with the upgraded Collider Detector at Fermilab
(CDFII) by using a dedicated dimuon trigger. We repeat the measurement on event samples selected with
different silicon-track quality requirements and obtain consistent results.
The observed ratio of LS to OS dimuons leads to a measurement of the average time-integrated
mixing probability of the mixture of b-flavored hadrons which decay semileptonically,
χbar= 0.126 ± 0.008, that is consistent with the average LEP value
χbar = 0.1259 ± 0.0042.
A more detailed summary of the results can be found in
CDFNOTE 10335 :
Measurement of the average time-integrated mixing probability of
b-flavored hadrons produced at the Tevatron
Below are the eps and gif versions of all figures meant for downloads.
Figure 1:
Normalized impact parameter distribution of muons produced in
semileptonic B decays for all simulated events (points).
The distributions for opposite-sign (line) and
like-sign (dotted line) B-Bbar events are shown.
Figure 2:
The projection of the two-dimensional impact parameter
distribution of OS muon pairs onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with tight silicon-quality requirements. The B-Bbar, C-Cbar,
and Prompt-Prompt components are also shown separately on top of the remaining
contributions. The BB and CC contributions include that of fake muons from heavy flavor production.
Figure 3:
The projection of the two-dimensional impact parameter
distribution of ++ muon pairs onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with tight silicon-quality requirements.
Figure 4:
The projection of the two-dimensional impact parameter
distribution of -- muon pairs onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with tight silicon-quality requirements.
Figure 5:
The projection of the two-dimensional impact parameter
distribution of OS dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standard silicon-quality requirements.
Figure 6:
The projection of the two-dimensional impact parameter
distribution of ++ dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standard silicon-quality requirements. The BP, CC,
and PP components are also shown separately on top of the remaining
contributions.
Figure 7:
The projection of the two-dimensional impact parameter
distribution of -- dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standard silicon-quality requirements.
Figure 8:
The projection of the two-dimensional impact parameter
distribution of OS dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standars silicon-quality requirements.
The B-Bbar+B-Bbar_{fake}, C-Cbar+C-Cbar_{fake}$,
PP, and "ghost" components are also shown separately on top of the remaining
contributions.
Figure 9:
The projection of the two-dimensional impact parameter
distribution of ++ dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standard silicon-quality requirements.
Figure 9:
The projection of the two-dimensional impact parameter
distribution of -- dimuons onto one of the two axes is
compared to the fit result (histogram).
Muons are selected with standard silicon-quality requirements.
