Measurement of the mass and natural width of the Higgs boson in the H to ZZ to 4l decay channel with the ATLAS detector

• Main Author: Spearman, William R
• Other Authors: Guimaraes da Costa, Joao
• Language: en_US
• Published: Harvard University 2014
• Subjects: Physics; Particle physics; ATLAS; CERN; Higgs boson; Higgs mass; Higgs width
• Online Access: http://dissertations.umi.com/gsas.harvard.inactive:11773; http://nrs.harvard.edu/urn-3:HUL.InstRepos:13070058

This thesis presents a measurement of the mass, natural width, and signal strength, defined as the yield normalized to the Standard Model prediction, of the Higgs boson in the \(H \rightarrow ZZ^{(*)} \rightarrow 4l\) decay channel using an approach which utilizes event-by-event detector response information. The measurement is performed on p-p collision data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The data corresponds to an integrated luminosity of \(25 fb^{-1}\) with center-of-mass energies of 7 TeV and 8 TeV. The measured mass of the Higgs boson is \(m_H = 124.57_{-0.43}^{+0.48} GeV\). The signal strength was estimated at \(\mu = 1.76_{-0.37}^{+0.46}\). Finally, the natural width of the Higgs was determined to be < 2.6 GeV with 95% confidence. The event-by-event approach used in this analysis involves the parameterization of the behavior of single leptons in the ATLAS detector and the convolution of a mass response with the Higgs truth distribution to derive the reconstruction level signal model. === Physics