Improved Search for Heavy Neutral Scalars A and H Using ttZ Events from 13 TeV pp Collisions at CMS

This thesis presents a search for heavy neutral scalars A and H via the cascade decay A->ZH with H->tt and semileptonic decays of the top quarks. The search is performed using proton-proton collision data recorded by the CMS experiment at sqrt(s) = 13 TeV during LHC Run 2, corresponding to an integrated luminosity of 138 fb^-1. The analysis targets events with three charged leptons, missing transverse momentum, and four or more jets, at least one of which is b-tagged. From these, a Z boson candidate and two top quark candidates are reconstructed, allowing reconstruction of the heavy resonances. No evidence for a signal is observed. Model-independent upper limits on the product of cross section and branching fraction are set for A masses from 430 to 2100 GeV and H masses from 330 to 2000 GeV, assuming narrow resonances. The results are used to constrain the parameter space of the type-II two-Higgs-doublet model, excluding regions relevant to electroweak baryogenesis. A statistical combination is performed with a complementary CMS search in the two-lepton final state, where the top quark pair decays entirely to hadrons. The combination improves the expected sensitivity and extends the excluded regions.

Author dc:creator

• Michelle Hawksworth (24400280)

• Physics
• Elementary Particles and High Energy

Statement dc:rights

• In Copyright
• Open Access after 2028-05-01

DOI dc:identifier

https://doi.org/10.25417/uic.32995328.v1

OAI identifier oai:identifier

oai:figshare.com:article/32995328