A Measurement of tex2html_wrap_inline34 from tex2html_wrap_inline36 with the CDF Detector

Abstract:

We report an updated direct measurement of the Standard Model CP violation parameter tex2html_wrap_inline40 using the CDF Detector at Fermilab. We use the entire Run-I data sample of 110 pbtex2html_wrap_inline42 of proton anti-proton collisions. Our previous published result used a sample of tex2html_wrap_inline44 events (tex2html_wrap_inline46 events) in which the tex2html_wrap_inline48 and tex2html_wrap_inline50 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 that have less precise lifetime information due to the fact they are not fully contained within the acceptance of the SVX. The signal sample consists of
tex2html_wrap_inline54 tex2html_wrap_inline56 events. A maximum likelihood fitting method is used to measure tex2html_wrap_inline58(stat+syst). We find the probability that tex2html_wrap_inline60 is 95%, using a Bayesian method, or alternatively, we calculate a 93% confidence interval of tex2html_wrap_inline62 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.

Documentation

Here is a conference style summary of the analysis.

Layperson summary of the sin(2beta) ananlysis.

Plots

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



CDF B Physics Group