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Mirror Color Symmetry Breaking in Twin Higgs Model

Hu, Wei (2021) Mirror Color Symmetry Breaking in Twin Higgs Model. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Many conventional approaches to the hierarchy problem necessitate colored top partners around the TeV scale, in tension with bounds from direct searches. The Mirror Twin Higgs (MTH) model address this by positing top partners that are neutral under the Standard Model (SM) gauge group. The SM Higgs emerges as a pseudo Nambu Goldstone boson (pNGB) from a spontaneously broken accidental global symmetry. A crucial ingredient is a $\ztwo$ mirror symmetry that exchanges SM fields with partner fields with equal couplings, removing the quadratic UV sensitivity. However, an exact mirror symmetry is in conflict with Higgs coupling measurements, the $\ztwo$ must be broken to achieve a viable model.

In this thesis, we describe a new dynamical approach. Starting from an exact $\ztwo$, we introduce an additional colored scalar field in the visible sector along with its twin partner field. Given a suitable potential, the mirror sector color scalar field obtains a vacuum expectation value and spontaneously breaks both the twin color gauge and $\ztwo$ symmetries.

Meanwhile, dramatic differences between the twin and visible sectors occur, in terms of the residual unbroken gauge symmetries, strong confinement scales, and particle spectra. Assuming a single colored scalar of triplet, sextet, or octet we describe five minimal possibilities. In several cases there is a residual color symmetry, either $SU(2)_c$ or $SO(3)_c$, featuring a low confinement scale relative to $\Lambda_{\rm QCD}$. Furthermore, there can be one or more unbroken abelian gauge symmetries. Couplings between the colored scalar and matter are also allowed, providing a new source of twin fermion masses. It implies a fraternal-like scenario by lifting the first and second generation twin fermions. A variety of correlated visible sector effects can be probed through precision measurements and collider searches, coming from baryon and lepton number violation, flavor changing processes, CP-violation, electroweak measurements, Higgs couplings, and direct searches at the LHC. This opens up new possibilities for a viable twin Higgs cosmology with interesting implications for the dark sector physics.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Hu, Weiweh40@pitt.eduweh40
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBatell,
Committee MemberFreitas,
Committee MemberWood-Vasey,
Committee MemberMueller,
Committee MemberMorningstar,
Date: 20 January 2021
Date Type: Publication
Defense Date: 29 July 2020
Approval Date: 20 January 2021
Submission Date: 17 November 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 140
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: Beyond Standard Model, Spontaneous Symmetry Breaking
Date Deposited: 20 Jan 2021 18:45
Last Modified: 20 Jan 2021 18:45


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