We report an updated direct measurement of the Standard Model CP
violation parameter using the CDF Detector at Fermilab.
We use the entire Run-I data sample of 110 pb of proton anti-proton
collisions. Our previous published result used a sample
of events ( events) in which
the and tracks were fully contained within the
silicon vertex detector (SVX) and therefore had precision lifetime
information. The SVX
provides precision vertex information for about 50% of the luminous region.
The same-side tagging method was used to identify
the flavor of the B meson at the time of production.
In this analysis,
we have combined three tagging methods: a same-side tag, a
soft-lepton tag, and a jet-charge tag, and also added events
less precise lifetime information due to the fact they are
not fully contained within the acceptance of the SVX.
The signal sample consists of
events. A maximum likelihood fitting method is used to measure (stat+syst). We find the probability that is 95%, using a Bayesian method, or alternatively, we calculate a 93% confidence interval of using the Feldman-Cousins method. This direct measurement is the best evidence for CP violation in the neutral B meson system to date and favors the Standard Model prediction of a large CP symmetry violation in the b quark system. This result supersedes our recent published result and should be considered preliminary.
Here is a conference style summary of the analysis.
Layperson summary of the sin(2beta) ananlysis.
Figure 1: Combined J/Psi K0s Mass
Figure 2: J/Psi K0s Mass (SVX muons)
Figure 3: J/Psi K0s Mass (non-SVX muons)
Figure 4: J/Psi K+ Mass (calibration sample)
Figure 5: CP Asymmetry vs. proper time
Figure 6: Sin(2beta) vs. dMd (dMd floated)
Figure 7: Sin(2beta) vs. Ln(L)
Figure 8: Rho-eta summary