Search for Neutral Heavy Scalars in ttZ Events Using 13 TeV pp Collisions at CMS
thesis
posted on 2024-12-01, 00:00authored bySahithi 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