A measurement of the Lambda-bottom lifetime using semileptonic decays and observation of the new state X(3872)

A preliminary study is presented of the semileptonic decay Λ b → Λcℓnu by searching for Λc-lepton pairs using the Run II ℓ + SVT(displaced track) sample collected by the CDF detector from Jan. 2002 to Jan. 2003. A total of 586 +/- 46 Λ c-lepton pairs are found. A parameterization method is used to correct for the SVT trigger bias and to understand the systematic uncertainty introduced by SVT in the lifetime measurement. Using an unbinned maximum-likelihood fit to the proper decay length distribution of 345 mu + Λ c pairs, a preliminary Λb lifetime of 399 +/- 38(stat) +/- 21(sys ) mum was obtained. The result is consistent with the Run I measurement of ctLb = 396 +/- 46(stat) +/- 21(sys) mu m.; Recently, the Belle Collaboration announced the observation of a new narrow state in exclusive B decays. They reported that the new state has a mass of 3872.0 +/- 0.6(stat) +/- 0.5(syst ) MeV/c2 and was observed via its decay to yp+p- . This state was immediately searched for and observed in the existing CDF data sample. CDF result uses inclusive production in pp¯ collision of this state instead of any exclusive channel. The CDF mass measurement of this new state has comparable errors to Belle. The mass is measured as 3871.3 +/- 0.7 +/- 0.4MeV/ c2 at CDF.