U(1) extensions to the standard model and phenomenological applications

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Georgilas, George
Γεωργιλάς, Γεώργιος

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Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Φυσικής

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In this thesis, I study a particular extension to the Standard Model of Particle Physics, namely the Beyond Standard Model Scenario of an additional U(1)’ symmetry to the SM symmetry group, which through Spontaneous Symmetry Breaking gives rise to a massive Z’ gauge boson. The phenomenology that is analyzed and studied is around the muon's anomalous magnetic moment and the origins of the Yukawa couplings. The models presented here, and which attempt to explain these phenomena, require a clear understanding of one-loop radiative contributions, the seesaw mechanism, and effective field theory, which are presented analytically and in great detail. Both models introduce a vector-like lepton. In the first model, the existence of a vector-like lepton explains the small muon mass by a seesaw mechanism, based on lepton-specific two Higgs doublet models with a local U(1)’ symmetry. The physical muon mass is generated due to the mixing between the vector-like lepton and the muon after the leptophilic Higgs doublet and the dark Higgs acquire VEVs. The non-decoupling effects of the vector-like lepton give rise to leading contributions to the muon g-2, thanks to the light Z’ and the light dark Higgs boson. In the second model, the ideas of inducing flavourful Z’ couplings via mixing with a vector-like fourth family, which carries gauged U(1)’ charges, and furthermore generate fermion mass hierarchies and mixing patterns without introducing any family symmetry, are fused to provide a connection between RK(*) and the origin of Yukawa couplings in the quark sector. In the last chapter, I suggest a different approach to the Origins of the Yukawa couplings, by introducing a modified form of the symmetry breaking mechanism, namely modifying the covariant derivative to include spinor fields. This mechanism generates in a natural way the Yukawa coupling terms to the theory, with the cost of introducing a scalar source and a tree-level Higgs-fermion scattering term. Despite this accomplishment, this mechanism needs to be modified in order to respect the observable measurements and the phenomenology of the SM.
IΣε αυτή την εργασία, μελετήθηκε ένα συγκεκριμένο είδος επέκτασης του Καθιερωμένου Προτύπου των Στοιχειωδών Σωματιδίων: η προσθήκη μιας επιπλέον Αβελιανής ομάδας στην ομάδα συμμετρίας του Καθιερωμένου Προτύπου. Ύστερα από το αυθόρμητο σπάσιμο συμμετρίας, η θεωρία αποκτά ένα επιπλέον έμμαζο διανυσματικό μποζόνιο, το ηλεκτρικά ουδέτερο Ζ’. Η φαινομενολογία που μελετήθηκε και αναλύθηκε σε αυτό το θεωρητικό πλαίσιο αφορά δύο μοντέλα, στα οποία εισάγοντας vector-like φερμιόνια στη θεωρία επιδιώκεται η εξήγηση της ασυνέπειας θεωρίας-πειράματος της ανώμαλης μαγνητικής ροπής του μιονίου, καθώς και της φυσικής προέλευσης των Yukawa συζεύξεων των φερμιονίων με το πεδίο Higgs.

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Quantum electrodynamics

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Quantum electrodynamics

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en

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Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Φυσικής

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Καντή, Παναγιώτα

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Καντή, Παναγιώτα
Λεοντάρης, Γεώργιος Κ.
Δέδες, Αθανάσιος

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Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών

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75 σ.

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Except where otherwised noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 United States