Measurement of $b$-quark jet production at $\sqrt{s}=7$~TeV with the CMS experiment

We describe a measurement of the inclusive $b$-jet production in pp collisions at $\sqrt{s}=$7 TeV. The analysis has been done on the first physics data collected by the CMS experiment at the Large Hadron Collider at CERN. We are using a simple secondary vertex high purity tagger, which is one of the most reliable $b$-taggers for this early measurement, for selecting a jet sample with high $b$-jet purity.\\ To measure the $b$-fractions in the tagged jet data sample, we make a template fit to the secondary vertex mass. Our estimation of the $b$-tagging efficiency is taken from Monte Carlo simulation. We find an overall good agreement between data and Pythia in the jet transverse momentum range 30~$< p_T <$~150 GeV and rapidity $\lvert y\rvert<$~2.0. We also observe a reasonable agreement between the MC@NLO calculation and the measured overall $b$-jet fraction, but observe significant shape differences in $p_T$ and $y$.