Truth and Lies about Beauty and Charm, Using top quark pair events as a spectroscope

This report describes the analysis of bottom quark fragmentation and hadronization in top-quark events. In both di- and semi-leptonic decay channels, we study the invariant mass distributions of $J/\Psi$-, $D^0$- and $D^{\pm}$- mesons, reconstructed in the two most probable b-jets. We study the kinematic properties of the events in the peak of the invariant mass distribution. For the latter study we use a statistical approach to disentangle background and signal contributions to the observed spectra with data, for different kinematic properties of the meson candidates. Different tunings of Monte Carlo simulations are compared. Our conclusion is that the default Monte Carlo simulation used by the CMS Collaboratio, Madgraph + Pythia + Z2*, performs reasonably well.