We have measured the?{sub b} lifetime using the exclusive decay?{sub b}→J/??, based on 1.2 fb−1 of data collected with the D0 detector during 2002-2006. From 171 reconstructed?{sub b} decays, where the J/? and? are identified via the decays J/??????????− and????????p?, we measured the?{sub b} lifetime to be?(?{sub b})=1.218{sub -0.115}{sup +0.130}(stat)±0.042(syst) ps. We also measured the B° lifetime in the decay B°→J/?(?+?−)K{sub S}°(?+?−) to be?(B°)=1.501{sub -0.074}{sup +0.078}(stat)±0.050(syst) ps, yielding a lifetime ratio of?(?{sub b})/?(B°)=0.811{sub -0.087}{sup +0.096}(stat)±0.034(syst =).
In this work we report a measurement of the [Lambda]0b baryon lifetime using the exclusive decay [Lambda]0b→ J/ [Psi][Lambda]0. The B0 meson lifetime is also measured in the topologically similar channel B0→ J/ K0S , which provides a crosscheck of the measurement procedure, and allows a direct determination of the ratio of the [Lambda]0b and the B0 lifetimes. The data used in this analysis were collected with the DØ detector during the complete Run II of the Fermilab Tevatron Collider, from 2002 to 2011, and correspond to an integrated luminosity of 10.4 fb-1 of proton-antiproton collisions at a center of mass energy √s = 1.96 TeV. We obtain [tau] ([Lambda]0b ) = 1.303 ± 0.075 (stat.) ± 0.035 (syst.) ps, [tau] (B0) = 1.508±0.025 (stat.)±0.043 (syst.) ps and [tau] ([Lambda]0b )/[tau] (B0) = 0.864± 0.052 (stat.)±0.033 (syst.). These measurements supersede previous results of the DØ Collaboration using the same decay channels. Our measurement of the lifetime ratio is in excellent agreement with theoretical predictions and compatible with the current world-average, but differs with the latest measurement of the CDF Collaboration in more than 2 standard deviations.
The authors report a measurement of the [Lambda]{sub b}° lifetime in the exclusive decay [Lambda]{sub b}° → J/[psi][Lambda]° in p{bar p} collisions at √s = 1.96 TeV using an integrated luminosity of 1.0 fb−1 of data collected by the CDF II detector at the Fermilab Tevatron. Using fully reconstructed decays, they measure [tau]([Lambda]{sub b}°) = 1.593{sub -0.078}{sup +0.083}(stat.) ± 0.033(syst.) ps. This is the single most precise measurement of [tau]([Lambda]{sub b}°) and is 3.2 [sigma] higher than the current world average.
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.
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The lifetime of the [Lambda]0b baryon (consisting of u, d and b quarks) is the theoretically most interesting of all b-hadron lifetimes. The lifetime of [Lambda]0b probes our understanding of how baryons with one heavy quark are put together and how they decay. Experimentally however, measurements of the [Lambda]0b lifetime have either lacked precision or have been inconsistent with one another. This thesis describes the measurement of [Lambda]0b lifetime in proton-antiproton collisions with center of mass energy of 1.96 TeV at Fermilab's Tevatron collider. Using 1070 ± 60pb-1 of data collected by the Collider Detector at Fermilab (CDF), a clean sample of about 3,000 fully-reconstructed [Lambda]0b →[Lambda]c+[pi]- decays (with [Lambda]+c subsequently decaying via [Lambda]+c → p+ K- [pi]+) is used to extract the lifetime of the [Lambda]0b baryon, which is found to be c[tau]([Lambda]0b) = 422.8 ± 13.8(stat) ± 8.8(syst)[mu]m. This is the most precise measurement of its kind, and is even better than the current world average. It also settles the recent controversy regarding the apparent inconsistency between CDF's other measurement and the rest of the world.
