Measurement of the $b$-tagging efficiency using events with jets containing muons

We present a measurement of the b-tagging efficiency using $32\;\rm pb^{-1}$ of data collected in 2010 with the CMS detector operating at the proton-proton LHC with $\sqrt{s} =$ 7 TeV. The measurement is based on data samples that have at least two reconstructed jets and a non-isolated muon close to one of the jets. The measurements are made as a function of the jet $p_T$ and $\eta$. Results are presented for different $b$-tagging algorithms that identify $b$-jets based on the track's impact parameters or by fully reconstructing the secondary decay vertex.