  The CMS experiment uses missing E_T to both measure processes in the Standard
Model and test models of physics beyond the Standard Model. These proceedings
show the performance of the missing E_T reconstruction evaluated by using 4.6
fb-1 of proton-proton collision data at the center-of-mass energy 7 TeV
collected in 2011 with the CMS detector at the Large Hadron Collider. Missing
E_T was reconstructed based on a particle-flow technique. Jet energy
corrections were propagated to missing E_T. After anomalous signals and events
were addressed, the missing E_T spectrum was well reproduced by MC simulation.
The multiple proton-proton interactions in a single bunch crossing, pile-up
events, degraded the performance of the missing E_T reconstruction. Mitigations
of this degradation have been developed.
