CMS reconstruction improvement for the muon tracking by the RPC chambers

The contribution of Resistive Plate Chamber (RPC) to muon reconstruction and identification in CMS has been studied on a sample of muons collected in proton-proton collisions at sqrt(s) = 7 TeV at the LHC in 2011. Muon tracks are reconstructed using the Drift Tubes in the central barrel region, Cathode Strip Chambers in the endcap region and RPC chambers in both the barrel and endcaps. Measured distributions of reconstructed hits in the RPCs crossed by muons from Z decays with a transverse momentum pT above 20 GeV/c are well reproduced by the Monte Carlo simulation. From the samples of J/psi and Z events, the muon reconstruction and identification efficiencies with and without the inclusion of the RPC hits in the track fitting are measured and compared with the simulation. Using RPC information in track reconstruction improves up to about 3% of offline reconstruction efficiency for the muons in the region of pT above 7 GeV/c, in good agreement with simulation.