The authors measure the mean lifetime, [tau] = 2/([Lambda]{sub L} + [Lambda]{sub H}), and the decay-width difference, [Delta][Lambda] = [Lambda]{sub L} - [Lambda]{sub H}, of the light and heavy mass eigenstates of the B{sub s}° meson, B{sub sL}° and B{sub sH}°, in B{sub s}° → J/[psi][phi] decays using 1.7 fb−1 of data collected with the CDF II detector at the Fermilab Tevatron p{bar p} collider. Assuming CP conservation, a good approximation for the B{sub s}° system in the standard model, they obtain [Delta][Lambda] = 0.076{sub -0.063}{sup +0.059}(stat.) ± 0.006(syst.) ps−1 and [tau] = 1.52 ± 0.04(stat.) ± 0.02(syst.) ps, the most precise measurements to date. The constraints on the weak phase and [Delta][Lambda] are consistent with CP conservation.
Over the past decades the current theoretical description, the Standard Model of elementary particle physics, was solidified by many measurements as the basic theory describing fundamental particles and their interactions. It is extremely successful in explaining the high-precision data collected by experiments so far. The Standard Model includes several intrinsic parameters which have to be measured in experiments. Independent analyses of different physical processes can constrain those parameters. By combining those measurements physicists might be sensitive to physics beyond the Standard Model. If they are inconsistent it allows to get a hint on the theory that might supersede the Standard Model. The goal of the analysis presented in this thesis is to measure some of these parameters in the B{sub s} meson system. The B{sub s} meson, consisting of an anti-b and s quark, is not a pure mass eigenstate, thus allowing a B{sub s} meson to oscillate into its antiparticle via weak interacting processes. This is a general feature of any neutral meson. The history of meson mixing measurements is more then 50 years old. It was first observed in the kaon system. The oscillation in the B{sub d} system was measured very precisely by the B factories, whereas the oscillation frequency of the B{sub s} was measured with more than 5[sigma] significance last year by CDF and first evidence for mixing in the D0 system was presented only this year.
The CP violating phase [beta] j/[Psi][Phi]s is measured in decays of B0s → J/[Psi][Phi]. This measurement uses 5.2 fb-1 of data collected in √s = 1.96 TeV p$\bar{p}$ collisions at the Fermilab Tevatron with the CDF Run-II detector. CP violation in the Bs0-$\bar{B}$s0 system is predicted to be very small in the Standard Model. However, several theories beyond the Standard Model allow enhancements to this quantity by heavier, New Physics particles entering second order weak mixing box diagrams. Previous measurements have hinted at a deviation from the Standard Model expectation value for [beta]sJ/[Psi][Phi] with a significance of approximately 2[sigma]. The measurement described in this thesis uses the highest statistics sample available to date in the Bs0 → J/[Psi][Phi] decay channel, where J/[Psi] → [mu]+[mu]- and [Phi] → K+K-. Furthermore, it contains several improvements over previous analyses, such as enhanced signal selection, fully calibrated particle ID and flavour tagging, and the inclusion of an additional decay component in the likelihood function. The added decay component considers S-wave states of KK pairs in the Bs0 → J/[Psi] K+K- channel. The results are presented as 2-dimensional frequentist confidence regions for [beta]sJ/[Psi][Phi] and [Delta][Gamma] (the width difference between the Bs0 mass eigenstates), and as a confidence interval for [beta]sJ/[Psi][Phi] of [0.02,0.52] U [1.08, 1.55] at the 68% confidence level. The measurement of the CP violating phase obtained in this thesis is complemented by the world's most precise measurement of the lifetime [tau]s = 1.53 ± 0.025 (stat.) ± 0.012 (syst.) ps and decay width difference [Delta][Gamma] = 0.075 ± 0.035 (stat.) ± 0.01 (syst.) ps-1 of the Bs0 meson, with the assumption of no CP violation.
The B{sub s} meson is an interesting particle to study because a sizable mixing induced CP violation in the B{sub s} -- {bar B}{sub s} system would be an indication for physics beyond the Standard Model. In this paper we present a measurement of the lifetime difference [Delta][Gamma] between the B{sub s} mass eigenstates and the CP violating phase in the decay B{sub s} → J/[psi][phi]. In 1.7 fb−1 of data collected with the CDF II detector at the Tevatron p{bar p} collider we measure [Delta][Gamma] = 0.076{sup +0.059}{sub -0.063} (stat.) ±0.006 (syst.) ps−1, well consistent with the Standard Model prediction, and a mean B{sub s} lifetime of c{sub tau}{sub s} = 456 ± 13 (stat.) ± (syst.) [mu]m. We find no evidence for CP violation.
This thesis describes a measurement of the B{sub d}{sup 0} lifetime in the decay to (J/{psi}K{sub S}{sup 0}), using 114 pb{sup -1} of data collected by the D0 experiment at the Tevatron from October 15, 2002, to June 10, 2003. The measurement is motivated by the tests of the Standard Model that it makes possible. These include tests of Heavy Quark Effective Theory predicting B-meson lifetimes, and of the complex phase in the CKM-matrix as the source of CP-violation in B{sub d}{sup 0} decays to (J/{psi}K{sub S}{sup 0}).
