4,428 research outputs found
Discrete and continuous symmetries in multi-Higgs-doublet models
We consider the Higgs sector of multi-Higgs-doublet models in the presence of
simple symmetries relating the various fields. We construct basis invariant
observables which may in principle be used to detect these symmetries for any
number of doublets. A categorization of the symmetries into classes is
required, which we perform in detail for the case of two and three Higgs
doublets.Comment: 13 pages, RevTex, references adde
Spontaneous CP Violation in the Next-to-Minimal Supersymmetric Standard Model Revisited
We re-examine spontaneous CP violation at the tree level in the context of
the next-to-minimal supersymmetric standard model (NMSSM) with two Higgs
doublets and a gauge singlet field. We analyse the most general Higgs potential
without a discrete Z_3 symmetry, and derive an upper bound on the mass of the
lightest neutral Higgs boson consistent with present experimental data. We
investigate, in particular, its dependence on the admixture and CP-violating
phase of the gauge singlet field, as well as on tan(beta). To assess the
viability of the spontaneous CP violation scenario, we estimate epsilon_K by
applying the mass insertion approximation. We find that a non-trivial flavour
structure in the soft-breaking A terms is required to account for the observed
CP violation in the neutral kaon sector. Furthermore, combining the
minimisation conditions for spontaneous CP violation with the constraints
coming from K0-K0bar mixing, we find that the upper bound on the lightest
Higgs-boson mass becomes stronger. We also point out that the electric dipole
moments of electron and neutron are a serious challenge for SUSY models with
spontaneous CP violation.Comment: 19 pages, LaTeX2e, 5 figures; matches the published versio
Flavour Changing Higgs Couplings in a Class of Two Higgs Doublet Models
We analyse various flavour changing processes like , as well as hadronic decays , in the framework of a class
of two Higgs doublet models where there are flavour changing neutral scalar
currents at tree level. These models have the remarkable feature of having
these flavour-violating couplings entirely determined by the CKM and PMNS
matrices as well as . The flavour structure of these scalar currents
results from a symmetry of the Lagrangian and therefore it is natural and
stable under the renormalization group. We show that in some of the models the
rates of the above flavour changing processes can reach the discovery level at
the LHC at 13 TeV even taking into account the stringent bounds on low energy
processes, in particular .Comment: 33 pages, 8 figures; matches version accepted for publicatio
Charge breaking bounds in the Zee model
We study the possibility that charge breaking minima occur in the Zee model.
We reach very different conclusions from those attained in simpler, two Higgs
doublet models, and the reason for this is traced back to the existence of
cubic terms in the potential. A scan of the Zee model's parameter space shows
that CB is restricted to a narrow region of values of the parameters
Leptonic Invariants, Neutrino Mass-Ordering and the Octant of
We point out that leptonic weak-basis invariants are an important tool for
the study of the properties of lepton flavour models. In particular, we show
that appropriately chosen invariants can give a clear indication of whether a
particular lepton flavour model favours normal or inverted hierarchy for
neutrino masses and what is the octant of . These invariants can
be evaluated in any conveniently chosen weak-basis and can also be expressed in
terms of neutrino masses, charged lepton masses, mixing angles and CP violation
phases.Comment: 10 pages, no figure
Non-Factorizable Phases, Yukawa Textures and the Size of sin (2 beta)
We emphasize the crucial r\^ ole played by non-factorizable phases in the
analysis of the Yukawa flavour structure performed in weak bases with Hermitian
mass matrices and with vanishing entries. We show that non-factorizable
phases are important in order to generate a sufficiently large .
A method is suggested to reconstruct the flavour structure of Yukawa couplings
from input experimental data both in this Hermitian basis and in a
non-Hermitian basis with a maximal number of texture zeros. The corresponding
Froggatt--Nielsen patterns are presented in both cases.Comment: 15 pages, 3 figure
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