Drell-Yan cross section measurement

We present preliminary results of the measurement of the Drell-Yan muon pair production cross section in pp collisions with the first data collected by the CMS detector at the LHC. Dedicated methods to determine trigger and reconstruction efficiencies, using a data-driven approach, will be presented. Methods to correct for the limited detector resolution will be discussed. The Drell-Yan muon pair production cross section is reported relative to the $Z \to \mu\mu$ peak cross section to avoid large systematic uncertainties, and was also compared with NNLO theoretical predictions.