Geometric minimization of highly symmetric potentials

in Journal of High Energy Physics [=JHEP] (2013), 2013

In non-minimal Higgs mechanisms, one often needs to minimize highly symmetric Higgs potentials. Here we propose a geometric way of doing it, which, surprisingly, is often much more efficient than the ... [more ▼]

In non-minimal Higgs mechanisms, one often needs to minimize highly symmetric Higgs potentials. Here we propose a geometric way of doing it, which, surprisingly, is often much more efficient than the usual method. By construction, it gives the global minimum for any set of free parameters of the potential, thus offering an intuitive understanding of how they affect the vacuum expectation values. For illustration, we apply this method to the S_4 and A_4-symmetric three-Higgs-doublet models. We find that at least three recent phenomenological analyses of the A_4-symmetric model used a local, not the global minimum. We discuss coexistence of minima of different types, and comment on the mathematical origin of geometrical CP-violation and on a new symmetry linking different minima. [less ▲]

Minimal Lepton Flavor Violating Realizations of Minimal Seesaw Models.

in Journal of High Energy Physics [=JHEP] (2012), JHEP 1207 (2012) 135(2012), 135-156

We study the implications of the global U(1)R symmetry present in minimal lepton flavor violating implementations of the seesaw mechanism for neutrino masses. In the context of minimal type I seesaw ... [more ▼]

We study the implications of the global U(1)R symmetry present in minimal lepton flavor violating implementations of the seesaw mechanism for neutrino masses. In the context of minimal type I seesaw scenarios with a slightly broken U(1)R, we show that, depending on the R-charge assignments, two classes of generic models can be identi fied. Models where the right-handed neutrino masses and the lepton number breaking scale are decoupled, and models where the parameters that slightly break the U(1)R induce a suppression in the light neutrino mass matrix. We show that within the fi rst class of models, contributions of right-handed neutrinos to charged lepton flavor violating processes are severely suppressed. Within the second class of models we study the charged lepton flavor violating phenomenology in detail, focusing on \ mu->e \gamma , \mu->3e and \mu- e conversion in nuclei. We show that sizable contributions to these processes are naturally obtained for right-handed neutrino masses at the TeV scale. We then discuss the interplay with the eff ects of the right- handed neutrino interactions on primordial B- L asymmetries,fi nding that sizable right-handed neutrino contributions to charged lepton flavor violating processes are incompatible with the requirement of generating (or even preserving preexisting) B-L asymmetries consistent with the observed baryon asymmetry of the Universe. [less ▲]

Higgs mechanism in the general Two-Higgs-Doublet Model

Master's dissertation (2009)

We first review the standard Higgs mechanism of the standard model. Then, in the second chapter, we motivate the introduction of a second doublet in the theory. In the third chapter, we talk about the ... [more ▼]

We first review the standard Higgs mechanism of the standard model. Then, in the second chapter, we motivate the introduction of a second doublet in the theory. In the third chapter, we talk about the reasons to study the most general two Higgs doublet model and introduce the Minkowski formalism introduced by I.P. Ivanov to simplify this problem. Finally, we study the masses of the Higgs bosons in the most general two-Higgs-doublet model (2HDM) in a basis-independent approach. We adapt the recently developed Minkowski-space formalism to this problem and calculate traces of any power of the mass matrix in a compact and reparametrization-invariant form. Our results can be used to gain insight into the dynamics of the scalar sector of the general 2HDM. [less ▲]