A Study Of Observability Of Higgs Boson Decay In Higgs Boson Decays To Two Z Mesons Decays To Four Leptons At Cms

The Standard Model (SM) of particle physics has been the most successful theory about fundamental particles and how they interact. In SM, the originally massless fundamental particles acquire masses in a process called the Higgs mechanism. This mechanism involves an additional particle, called the Higgs boson, whose responsibility is to break the electroweak symmetry and help those massless particles acquire masses. With the discovery of the top quark at Tevatron in 1995, the Higgs boson remains to be the only unfound fundamental particle in the Standard Model. The discovery of the Higgs boson would greatly increase our understanding of the origin of the mass. One of the most important objectives of the LHC experiment is to discover the Higgs boson. At LHC, the CMS experiment is optimized for the search of the Higgs boson over a mass range up to 1 TeV. Among all Higgs decay channels, <italic> H</italic> &rarr; <italic>ZZ</italic> &rarr; 4<italic>l</italic> is one of the most promising channels to search the SM Higgs boson at CMS. This study concentrates on the observability of the SM Higgs boson in <italic> H</italic> &rarr; <italic>ZZ</italic> &rarr; 4<italic>l</italic> channel at CMS. The <italic>H</italic> &rarr; <italic>ZZ</italic> &rarr; 4<italic>l</italic> signal has been investigated against its main background processes <italic> ZZ</italic>(*) &rarr; 4<italic>l</italic>, <italic>Zbb&macr;</italic> &rarr; 4<italic>l</italic> + <italic>X</italic> and <italic>tt&macr;</italic> &rarr; 4<italic>l</italic> + <italic>X</italic> by applying various selections and cuts. The event generation and preselection have been done with CMKIN interfaced with PYTHIA and COMPHEP, the simulation of the preselection and reconstruction has been done with the fast simulation software CMSJET. The result presented in this work shows that after 1-year of LHC running at it design luminosity phase, it is inevitable to claim the discovery of the SM Higgs boson in this <italic>H</italic> &rarr; <italic>ZZ</italic> &rarr; 4<italic> l</italic> channel, if the Higgs boson has a mass of 200&ndash;600 GeV. For very heavy Higgs boson (<italic>m_H</italic> &sim; 700 <italic> GeV</italic> or above), the Higgs boson signal may be observed, but the statistics is too low. The observability for low luminosity phase is also studied.