New Measurements from Fully Reconstructed Hadronic Final States of the $B^0_2$ Meson at CDF II Experiment PDF Download

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Languages : en
Pages : 164

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Book Description
This thesis reports the reconstruction and lifetime measurement of B+, B$0/atop{d}$ and B$0/atop{s}$ mesons, performed using fully reconstructed hadronic decays collected by a dedicated trigger at CDF II experiment. This dedicated trigger selects significantly displaced tracks from primary vertex of p$\bar{p}$ collisions generated at Tevatron collider, obtaining, in this way, huge data samples enriched of long-lived particles, and is therefore suitable for reconstruction of B meson in hadronic decay modes. Due to the trigger track impact parameter selections, the proper decay time distributions of the B mesons no longer follow a simply exponential decay law. This complicates the lifetime measurement and requires a correct understanding and treatment of all the involved effects to keep systematic uncertainties under control. This thesis presents a method to extract the lifetime of B mesons in "ct- biased" samples, based on a Monte Carlo approach, to correct for the effects of the trigger and analysis selections. We present the results of this method when applied on fully re- constructed decays of B collected by CDF II in the data taking runs up to August 2004, corresponding to an integrated luminosity of about 360 pb-1. The lifetimes are extracted using the decay modes B+ 2!$\bar{D}$0[pi]+, B$0\atop{d}$ 2!D-[pi]+, B$0\atop{d}$ 2!D-[pi]+[pi]-[pi]+, B$0\atop{s}$ 2!D$-\atop{s}$[pi]+ and B$0\atop{s}$ 2!D$-\atop{s}$ [pi]+[pi]-[pi]+(and c.c.) and performing combined mass-lifetime unbinned maximum likelihood fits.