Title: How Wide is the Higgs Boson: Off-shell Constraints from CMS


The recently discovered Higgs boson is a completely new form of matter-energy and is believed to be a manifestation of the all-penetrating Higgs field responsible for generating mass of all elementary particles. It has been observed as a resonance in the decay to a pair of two vector bosons on ATLAS and CMS experiments at LHC. The width of this resonance is expected to be just about 4 MeV, yet experimental resolution allowed us to set an upper limit on the width of about 3400 MeV. However, an interplay between the off-shell suppression of either the Higgs boson production or the vector bosons in its decay allows a new technique for a measurement of the Higgs boson width. Using the data collected by the CMS experiment at the LHC in 2011 and 2012, we perform a simultaneous maximum likelihood fit to the measured kinematic distributions of four leptons near the resonance peak and above the Z-boson pair production threshold, including the final states with neutrinos. This leads to an upper limit on the Higgs boson width of 22 MeV. Theoretical assumptions and experimental techniques leading to this measurement will be discussed.