Top Quark Pair Cross Section Measurements at CMS

Measurements of inclusive and differential top-quark pair production cross sections at a center of mass energy of 8 and 7 TeV are presented. The total cross section is measured in the lepton+jets and the dileptonic decay modes. Differential cross sections are obtained as a function of various kinematic observables, including the transverse momentum and rapidity of the (anti)top quark, kinematics of the top-antitop system, and jet multiplicity in the event. The precise results are used to extract the strong coupling constant from inclusive top-pair production cross sections. All measurements use LHC data collected by the CMS experiment in 2011 and 2012.