Fermion mass splitting in the technicolor coupled scenario
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Regular Article - Theoretical Physics
Fermion mass splitting in the technicolor coupled scenario A. Doff1,a , A. A. Natale2,b 1 2
Universidade Tecnológica Federal do Paraná - UTFPR - DAFIS, Av. Monteiro Lobato Km 04, Ponta Grossa, PR 84016-210, Brazil Instituto de Física Teórica, UNESP, Rua Dr. Bento T. Ferraz, 271, Bloco II, São Paulo, SP 01140-070, Brazil
Received: 2 March 2020 / Accepted: 20 July 2020 © The Author(s) 2020
Abstract We discuss fermion mass generation in unified models where QCD and technicolor (or any two strongly interacting theories) have their Schwinger–Dyson equations coupled. In this case the technicolor (TC) and QCD selfenergies are modified in comparison with the behavior observed in the isolated theories. In these models the pseudoGoldstone boson masses are much higher than the ones obtained in different contexts, and phenomenological signals, except from a light scalar composite boson, will be quite difficult to be observed at present collider energies. The most noticeable fact of these models is how the mass splitting between the different ordinary fermions is generated. We discuss how a necessary horizontal (or family) symmetry can be implemented in order to generate the mass splitting between fermions of different generations; how the fermionic mass spectrum may be modified due to GUT interactions, as well as how the mass splitting within the same fermionic generation are generated due to electroweak and GUT interactions.
1 Introduction The hierarchy and triviality problems related to the existence of fundamental scalar bosons have been discussed for a long time. The first attempts to solve these problems were proposed forty years ago in the seminal papers by Weinberg [1] and Susskind [2]. In these works the fundamental scalar boson that would be responsible for the Standard Model (SM) gauge symmetry breaking was substituted by a composite scalar boson generated by a new strong interaction dubbed as Technicolor (TC). This proposal was incorporated in the model of Farhi and Susskind [3] together with the idea that Nature may also have a Grand Unified Theory (GUT). These type of models were reviewed in Refs. [4,5]. The possible existence of composite scalar bosons and a GUT are beautiful a e-mail:
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and naturally expected ideas. It is worth remembering that much that it was learned up to now about symmetry breaking involves a composite scalar boson (as in the QCD chiral symmetry breaking and in the microscopic BCS theory of superconductivity), and the SM convergence of interactions at high energy seems to indicate the presence of a GUT. Unfortunately, it is also known how difficult is to build a phenomenologically viable model along these lines [6–8]. TC models continue to be studied although they present several phenomenological problems [6,9–13,15]. Most of these problems are related to the soft behavior of the technifermions self-energy, and they can be ameliorated if the TC theo
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