Measurement of the Lambda(b) Lifetime in the Exclusive Decay Lambda(b) ---] J


Book Description

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 =).




Measurement of the $\Lambda^0_b$ Lifetime in the Exclusive Decay $\Lambda^0_b \rightarrow J/\psi \Lambda^0$ with the \D0~detector


Book Description

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.










Measurement of Lifetime and Decay-Width Difference in B0s -] J/psi Phi Decays


Book Description

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.




B Lifetimes and X, Y, Z States at the Tevatron


Book Description

A measurement of b-hadron lifetimes in the fully reconstructed decay modes B 2!J/[psi]K+, B° 2!J/[psi]K*°, B° 2!J/[psi]K{sub S}°, and [Lambda]{sub b}° 2!J/[psi] [Lambda]° is reported using data corresponding to an integrated luminosity of 4.3 fb−1, collected by the CDF II detector at the Fermilab Tevatron. The measured values are [tau](B+) = 1.639 ± 0.009(stat) ± 0.009(syst) ps, [tau](B°) = 1.507 ± 0.010(stat) ± 0.008(syst) ps and [tau]([Lambda]{sub b}°) = 1.537 ± 0.045(stat) ± 0.014(syst) ps. The lifetime ratios are [tau](B+)/[tau](B°) - 1.088 ± 0.009(stat) ± 0.004(syst) and [tau]([Lambda]{sub b}°)/[tau](B°) = 1.020 ± 0.030(stat) ± 0.008(syst). These are the most precise measurements of these quantities from a single experiment. Observation is also reported for a structure near the J/[psi][phi] threshold, in B+ to J/[psi][phi]K+ decays with an integrated luminosity of 6.0 fb−1 and a statistical significance of 5 standard deviations. There are 19 ± 6 events observed for this structure at a mass of 4143.4{sub -3.0}{sup +2.9} ± 0.6 MeV/c2 and a width of 15.3{sub -6.1}{sup +10.4} ± 2.5 MeV/c2.