Performance of muon identification in pp collisions at s**0.5 = 7 TeV

The performance of muon identification in CMS has been studied on a sample of muons corresponding to an integrated luminosity of up to 84 nb$^{-1}$ collected in pp collisions at $\sqrt{s}$ = 7 TeV at the LHC. Measured distributions of basic muon-track quantities are well reproduced by the Monte Carlo simulation. Efficiencies of various high-level trigger, identification, and reconstruction algorithms have been measured in the muon momentum range up to about 15 GeV/$c$, and found to agree typically within 5-10\% of expectations. The probability to mis-identify kaons or pions as muons due to their decay in-flight agrees with predictions from simulation. The punch-through probability for protons with momentum between 3 and 10 GeV/$c$ was measured to be (5.3 $\pm$ 0.8 (stat.))$\cdot 10^{-4}$, in agreement with expectations.