Measurement of the top quark pair production cross section in pp collisions at 7 TeV center of mass energy using secondary vertex b-tagging

We present a measurement of top quark pair production cross section using 36 pb$^{-1}$ of data collected by the CMS detector in $pp$ collisions at a center-of-mass energy of 7 TeV. We select events containing one isolated muon, high missing transverse energy and at least three energetic jets. After using a data driven method to estimate the amount of QCD in our preselected data, further separation of the signal from the W boson background was attained through the identification of the $b$-jets in the events by reconstructing secondary vertices. The cross section is extracted from the excess of tagged events with at least three jets over the background prediction.