Measurement of Differential ${\rm t}\bar{\rm t}$ Cross Sections at 7 TeV

A measurement is presented of the normalized differential cross sections of top-quark pair production in pp collisions at a center of mass energy of 7 TeV, using 1.1 fb$^{-1}$ of data collected in 2011 by the CMS experiment. The measurement is performed using five different final states with one or two muons or electrons in the final state. The event selections yield high purity ${\rm t}\bar{\rm t}$ samples. Kinematic reconstructions are performed to obtain full information of the top quarks, the ${\rm t}\bar{\rm t}$ system and the final state leptons. The results are compared to several QCD predictions up to next-to-leading order.