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Searching for Physics Beyond the Standard Model: From Neutrinos to the Higgs Bosons

Qin, Han (2022) Searching for Physics Beyond the Standard Model: From Neutrinos to the Higgs Bosons. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This thesis consists of several projects of particle physics phenomenology in two major directions: (1) search for new physics effects on Higgs couplings at high energy scales; (2) realization of a UV-complete model of neutrino mass and non-standard interactions, accompanied by its phenomenological signatures at hadron colliders.

In the search of the ``Beyond the Standard Model'' (BSM) effects on Higgs couplings, we first explore the off-shell Higgs boson $(h)$ measurement in the ${pp \to h^* \to Z(\ell^{+}\ell^{-})Z(\nu\bar{\nu})}$
channel at the high-luminosity (HL) LHC. The new physics sensitivity is parametrized in terms of the Higgs boson width, dimension-6 operators in the effective field theory, and a non-local Higgs-top coupling form factor. In another project along the same direction, we explore the sensitivity to new physics for the coupling of Higgs boson and top quark ($t$) at high energy scales with the process $pp\to t\bar{t}h$ which probes the coupling in both space-like and time-like domains at a high scale, complementary to the off-shell Higgs processes in time-like domain. Both channels present strong sensitivities to the new physics scale and will be studied by the ATLAS and CMS collaborations.

In the aspect of BSM effects on neutrino physics, we study the non-standard interactions of neutrinos with light leptonic scalars ($\phi$) in a global $(B-L)$-conserved ultraviolet (UV)-complete model. The model utilizes Type-II seesaw motivated interactions with an $SU(2)_L$-triplet scalar and an additional singlet scalar. The UV-completion leads to an enriched spectrum and new observable signatures. We examine the low-energy lepton flavor violation constraints, as well as the perturbativity and unitarity constraints on model parameters. Then we lay out a search strategy for unique signatures of the model. We present the mass reach of the doubly-charged scalar at HL-LHC and future 100 TeV hadron collider, we also demonstrate that the mass of $\phi$ can be determined at about 10\% accuracy at HL-LHC for the large Yukawa coupling scenario even it escapes as missing momentum from detectors.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Qin, Hanhaq10@pitt.eduhaq100000-0001-5611-9463
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairHan,
Committee MemberFreitas,
Committee MemberLevy,
Committee MemberPaolone,
Committee MemberPenco,
Date: 12 October 2022
Date Type: Publication
Defense Date: 28 April 2022
Approval Date: 12 October 2022
Submission Date: 18 May 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 122
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Higgs boson, Large Hadron Collider, New Physics Search, High Pt, Off-shell, Neutrino self-interaction, Leptonic scalars
Date Deposited: 12 Oct 2022 16:11
Last Modified: 12 Oct 2022 16:11


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