New measurements from fully reconstructed hadronic final states of the $B^0_2$ meson at CDF II experiment

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+ → $\bar{D}$0π+,B$0\atop{d}$ → D-π+, B$0\atop{d}$ → D-π+π-π+, B$0\atop{s}$ → D$-\atop{s}$π+ and B$0\atop{s}$ → D$-\atop{s}$ π+π-π+(and c.c.) and performing combined mass-lifetime unbinned maximum likelihood fits.