Date of Award

Spring 1-1-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

John P. Cumalat

Second Advisor

Kevin Stenson

Third Advisor

Stephen Wagner

Fourth Advisor

Oliver DeWolfe

Fifth Advisor

Webster Cash

Abstract

Two searches for heavy neutral resonances, known as Z′, decaying to back-to-back tau pairs are completed using the Compact Muon Solenoid detector at the Large Hadron Collider. The first, based on data accumulated during the 2012 data-taking run at √s = 8 TeV, focuses on the fully-leptonic τeτμ channel, in which one tau decays to an electron and the other to a muon. The second, performed during the 2015 run at √s = 13 TeV, includes four major decay channels: the τeτμ channel, the τeτh channel (in which one tau decays to an electron and the other decays hadronically into a jet), the τμτh channel (in which one tau decays to a muon and the other decays hadronically), and the τhτh channel (in which both taus decay into jets). Each search employs a hybrid of background estimation strategies using both Monte Carlo simulation and data-driven methods. The presence of neutrinos in the decays necessitates the use of missing energy in the final mass calculation. In both searches, observed data are found to be in agreement with Standard Model expectation and no excesses are observed. Limits are placed on the Z′ mass at 95 % confidence level such that, if the Z′ exists, its mass must be greater than 2.1 TeV.

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