Search For A Z Boson In The Dimuon Channel In Pp Collisions At Square Root Symbols

The Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN) in Geneva, Switzerland has great physics potential in discovering many possible new particles beyond the standard model (SM) over a mass range around the TeV scale. Many extensions of the SM predict the existence of new heavy gauge bosons. Among these a simplest extension is the one that involves an additional U(1) gauge group with an associated neutral gauge boson, usually labeled as Z'. One of such extensions is called Sequential Standard Model (SSM) which includes a neutral gauge boson, Z'[subscript SSM] with the same couplings to quarks and leptons as the SM Z boson. Although this model is not gauge invariant but it has been traditionally considered by experiments studying high mass resonances. Other models, such as the superstring inspired E6 model, have a more complex gauge group structure with a corresponding neutral gauge boson denoted as Z'[subscrit psi]. In this dissertation, we report the results from the search of new heavy neutral gauge bosons, Z', using pp collision data at center-of-mass energies [square root symbol]s = 7 TeV and 8 TeV collected with the CMS detector during the LHC Runs in 2011 and 2012 corresponding to an integrated luminosity of 5.3 fb−1 and 20.6 fb−1, respectively. This dissertation describes a search for such a new heavy particles decaying into muon pairs. The search is performed by comparing the reconstructed dimuon invariant mass spectrum to that of the SM expectations. Since no significant excess is found, we set upper limit on the ratio of the cross section times branching ratio for the decay of a new boson (Z') to the Z boson at the 95% confidence level (CL) using a Bayesian approach. For the dimoun channel, Z'[subscript SSM] can be excluded below 2.77 TeV and Z'[subscript psi] below 2.43 TeV. This limit is combined with the limit obtained in the dielectron channel and used as a combined (dilepton) limit, so that Z'[subscript SSM] can be excluded below 2.96 TeV and Z'[subscript psi] below 2.6 TeV and converted into lower limit on the masses of SSM Z' boson and E6 Z' boson. The task of the Muon Endcap Alignment is to provide absolute positions of Cathode Strip Chambers (CSCs) in r[subscript phi] and Z coordinates of CMS. The Muon endcap hardware alignment system is designed to continuously monitor the actual positions of the CSCs relative to the tracking system. The Muon endcap alignment system is required to monitor chamber positions with 75-200 [subscript mu]m accuracy in r[subscript phi], 400 [subscript mu]m in the radial direction and ~1 mm in Z direction. In this dissertation, we also study the alignment performance for the r[subscript phi] coordinates in terms of resolution and precision achieved with full optical sensor systems.