Measurement of the t t cross section in the lepton-plus-jets Channel in CMS

The Large Hadron Collider will produce top quark pairs copiously, which will permit to perform a rich top quark physics program. We describe plans for the measurement of the top quark pair cross section in the lepton-plus-jets channel at a center-of-mass energy of 10 TeV using an integrated luminosity of about 20 inverse pico barn. The selected events contain one muon or one electron and at least four jets in the final state. We present methods to select the top quark pair events, to measure the t t cross section and to estimate the W/Z production and QCD multijet background in a data-driven way. The statistical and the main systematical uncertainties are also estimated.