Measurements of the properties of the Higgs-like Boson in the four lepton decay channel with the ATLAS detector.

摘要

On July 4, 2012, experimental physicists from both the A Toroidal LHC Apparatus (ATLAS), and the Compact Muon Solenoid (CMS) experiments at the Large Hadron Collider(LHC), reported evidence for the existence of a particle consistent with the Higgs boson at the level of 5 standard deviations, with a mass around 125 GeV. In March 2013, in the light of the updated ATLAS and CMS results, CERN announced that the new particle was indeed a Higgs boson. Having analyzed two-and-a-half times more data than was available for the discovery announcement in July, the confidence of observation has risen to 10 standard deviations. The experiments were also able to show that the properties of the particle as well as the ways it interacts with other particles were well-matched with those of a Higgs boson, which is expected to have spin 0 and even(+) parity.;This dissertation presents Higgs property measurements using the "golden" channel Higgs decay to four leptons. My key contribution has been the analysis of the spin-parity quantum numbers, one of the essential measurements to establishing the new boson as the Higgs boson. This analysis is performed on events that are most consistent with decays of the new boson. The Higgs-like boson is found to be compatible with the SM expectation of JP = 0+ when compared pairwise with other hypothesis.