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  • Flavour symmetries in a renormalizable SO(10) model
    Publication . Ferreira, Pedro Miguel; Grimus, W.; Jurciukonis, D.; Lavoura, L.
    In the context of a renormalizable supersymmetric SO(10) Grand Unified Theory, we consider the fermion mass matrices generated by the Yukawa couplings to a 10 circle plus 120 circle plus (126) over bar representation of scalars. We perform a complete investigation of the possibilities of imposing flavour symmetries in this scenario; the purpose is to reduce the number of Yukawa coupling constants in order to identify potentially predictive models. We have found that there are only 14 inequivalent cases of Yukawa coupling matrices, out of which 13 cases are generated by 74 symmetries, with suitable n, and one case is generated by a Z(2) x Z(2) symmetry. A numerical analysis of the 14 cases reveals that only two of them-dubbed A and B in the present paper allow good fits to the experimentally known fermion masses and mixings. (C) 2016 The Authors. Published by Elsevier B.V.
  • A three Higgs doublet model with symmetry-suppressed flavour changing neutral currents
    Publication . Das, Dipankar; Ferreira, Pedro Miguel; Morais, António P.; Padilla-Gay, Ian; Pasechnik, Roman; Rodrigues, J. Pedro
    We construct a three-Higgs doublet model with a flavour non-universal U(1) x DOUBLE-STRUCK CAPITAL Z(2) symmetry. That symmetry induces suppressed flavour-changing interactions mediated by neutral scalars. New scalars with masses below the TeV scale can still successfully negotiate the constraints arising from flavour data. Such a model can thus encourage direct searches for extra Higgs bosons in the future collider experiments, and includes a non-trivial flavour structure.
  • Symmetries of the 2HDM: an invariant formulation and consequences
    Publication . Ferreira, Pedro Miguel; Grzadkowski, B.; Ogreid, Odd Magne; Osland, P.
    Symmetries of the Two-Higgs-Doublet Model (2HDM) potential that can be extended to the whole Lagrangian, i.e. the CP-symmetries CP1, CP2, CP3 and the Higgs-family symmetries Z(2), U(1) and SO(3) are discussed. Sufficient and necessary conditions in terms of constraints on masses and physical couplings for the potential to respect each of these symmetries are found. Each symmetry can be realized through several alternative cases, each case being a set of relations among physical parameters. We will show that some of those relations are invariant under the renormalization group, but others are not. The cases corresponding to each symmetry group are illustrated by analyzing the interplay between the potential and the vacuum expectation values.