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Two Higgs doublets and a complex singlet: disentangling the decay topologies and associated phenomenology
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
Number of Authors: 22018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 12, article id 044Article in journal (Refereed) Published
Abstract [en]

We present a systematic study of an extension of the Standard Model (SM) with two Higgs doublets and one complex singlet (2HDM+S). In order to gain analytical understanding of the parameter space, we re-parameterize the 27 parameters in the Lagrangian by quantities more closely related to physical observables: physical masses, mixing angles, trilinear and quadratic couplings, and vacuum expectation values. Embedding the 125 GeV SM-like Higgs boson observed at the LHC places stringent constraints on the parameter space. In particular, the mixing of the SM-like interaction state with the remaining states is severely constrained, requiring approximate alignment without decoupling in the region of parameter space where the additional Higgs bosons are light enough to be accessible at the LHC. In contrast to 2HDM models, large branching ratios of the heavy Higgs bosons into two lighter Higgs bosons or a light Higgs and a Z boson, so-called Higgs cascade decays, are ubiquitous in the 2HDM+S. Using currently available limits, future projections, and our own collider simulations, we show that combining different final states arising from Higgs cascades would allow to probe most of the interesting region of parameter space with Higgs boson masses up to 1 TeV at the LHC with L = 3000 fb(-1) of data.

Place, publisher, year, edition, pages
2018. no 12, article id 044
Keywords [en]
Beyond Standard Model, Higgs Physics
National Category
Physical Sciences
Research subject
Theoretical Physics
Identifiers
URN: urn:nbn:se:su:diva-163533DOI: 10.1007/JHEP12(2018)044ISI: 000453294300007OAI: oai:DiVA.org:su-163533DiVA, id: diva2:1276377
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-04-25Bibliographically approved
In thesis
1. Dark Matter, Ancient Rocks, a Band of Higgs Bosons, and a Big Collider: or, Models of New Physics and Some Ways to Probe Them
Open this publication in new window or tab >>Dark Matter, Ancient Rocks, a Band of Higgs Bosons, and a Big Collider: or, Models of New Physics and Some Ways to Probe Them
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The past ~ 50 years have seen a remarkable success of particle physics. In the 1970s, the Standard Model was formulated and in 2012 its final ingredient, the Higgs boson, was discovered at the Large Hadron Collider (LHC). The Standard Model describes virtually all particle physics observable in the laboratory. However, despite this success, the Standard Model has a number of shortcomings. Some problems stem from its mathematical structure, most famously the hierarchy problem. Further, the Standard Model fails to describe the composition of our Universe, for example, it cannot explain the observed Dark Matter. Thus, the need for physics beyond the Standard Model is clear. A long series of experiments has been conducted to search for this new physics. Alas, these experiments came up empty handed.This thesis discusses two lines of work: 1) Arguably, the Higgs sector of the Standard Model is its least constrained part and simultaneously intimately related to many of the Standard Model's shortcomings. We discuss models extending the Higgs sector, both in a general and in a supersymmetric setting, and how they can be probed at the LHC. 2) A century after the first evidence for Dark Matter emerged, we still don't know what it is made up of. We discuss some models for Dark Matter, including axions and a particular model for Weakly Interacting Massive Particle (WIMP) Dark Matter. Then, we present some methods to search for WIMP Dark Matter, focusing on paleo-detectors, a proposed method where one would search for the traces of WIMP-nucleus interactions left in ancient minerals. 

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2019. p. 89
Keywords
particle phenomenology, supersymmetry, dark matter, higgs boson
National Category
Physical Sciences
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-167406 (URN)978-91-7797-713-1 (ISBN)978-91-7797-714-8 (ISBN)
Public defence
2019-06-12, sal FB52, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Accepted. Paper 8: Manuscript.

Available from: 2019-05-20 Created: 2019-03-28 Last updated: 2019-05-21Bibliographically approved

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