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Search for Neutral Heavy Scalars in ttZ Events Using 13 TeV pp Collisions at CMS

thesis
posted on 2024-12-01, 00:00 authored by Sahithi Rudrabhatla
This thesis presents a search for a heavy pseudoscalar particle, A, which decays into a lighter scalar, H, and a Z boson within the Two-Higgs-Doublet Model (2HDM). We focus on Z boson decays to leptons, with H decays into a t t ̄ pair. The search uses the Asimov dataset– a theoretical dataset generated to predict the expected results for discovery and exclusion based on conditions from proton-proton collisions at the LHC, at integrated luminosity of 138f b−1, as recorded by the CMS detector. The analysis focuses on events with three charged leptons, two of which come from the Z boson decay and one from a top quark decay. The expected results suggest the search has high sensitivity, showing discovery potential across much of the 2HDM Type-II parameter space, with possible deviations from the Standard Model background exceeding 5σ significance. The search sets upper limits on the cross-section times branching ratio, assuming narrow particle widths, for A masses up to 2100 GeV and H masses up to 1900 GeV. The results are interpreted in the 2HDM Type-II framework to exclude certain regions of parameter space at the 95% confidence level as a function of particle masses and variables such as tanβ and cos(β−α). The findings highlight the potential reach implications of future search in this parameter region.

History

Advisor

Corrinne Mills

Department

Physics

Degree Grantor

University of Illinois Chicago

Degree Level

  • Doctoral

Degree name

PhD, Doctor of Philosophy

Committee Member

Cecilia Gerber Richard Cavanaugh James Unwin Carlos Wagner

Thesis type

application/pdf

Language

  • en

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