We present a measurement of the CP-violating parameter _J/ _s
using approximately 6500B0s ! J/ _ decays reconstructed with the CDF II
detector in a sample of p¯p collisions at ps = 1.96 TeV corresponding
to 5.2 fb−1 integrated luminosity produced by the Tevatron Collider
at Fermilab. We find the CP-violating phase to be within the range
_J/ _s 2 [0.02, 0.52] [ [1.08, 1.55] at 68% confidence level where
the coverage property of the quoted interval is guaranteed using a
frequentist statistical analysis. This result is in agreement with the
standard model expectation at the level of about one Gaussian standard
deviation. We consider the inclusion of a potential S-wave contribution
to the B0s ! J/ K+K− final state which is found to be negligible over
the mass interval 1.009 < m(K+K−) < 1.028 GeV/c2. Assuming the
standard model prediction for the CP-violating phase _J/ _s , we find
the B0s decay width difference to be _s = 0.075 ± 0.035 (stat)
± 0.006(syst) ps−1. We also present the most precise measurements of
the B0s mean lifetime _ (B0s ) = 1.529 ± 0.025 (stat) ± 0.012 (syst)
ps, the polarization fractions|A0(0)|2 = 0.524±0.013 (stat)±0.015
(syst) and |Ak(0)|2 = 0.231±0.014(stat)±0.015 (syst), as well as the
strong phase _? = 2.95 ± 0.64(stat) ± 0.07 (syst) rad. In addition,
we report an alternative Bayesian analysis that gives results consistent
with the frequentist approach.
Thank You,
Stephanie A. Schuler
Fermi National Accelerator Laboratory (Fermilab)
PPD/Support Services/Administrative Support/CDF
MS 318 (CDF PTKMPS 171-I)
Office: 1-630-840-4136 Fax: 1-630-840-6315
<mailto:steph@fnal.gov> steph@fnal.gov