Symmetry Constrained Two Higgs Doublet Models

We study Two-Higgs-Doublet Models (2HDM) where Abelian symmetries have been introduced, leading to a drastic reduction in the number of free parameters in the 2HDM. Our analysis is inspired in BGL models, where, as the result of a symmetry of the Lagrangian, there are tree-level scalar mediated Flavour-Changing-Neutral-Currents, with the flavour structure depending only on the CKM matrix. A systematic analysis is done on the various possible schemes, which are classified in different classes, depending on the way the extra symmetries constrain the matrices of couplings defining the flavour structure of the scalar mediated neutral currents. All the resulting flavour textures of the Yukawa couplings are stable under renormalisation since they result from symmetries imposed at the Lagrangian level. We also present a brief phenomenological analysis of the most salient features of each class of symmetry constrained 2HDM.Comment: 30 pages, 5 Table

A viable A4A_4 3HDM theory of quark mass matrices

It is known that a three Higgs doublet model (3HDM)symmetric under an exact $A_4$ symmetry is not compatible with nonzero quark masses and/or non-block-diagonal CKM matrix. We show that a 3HDM with softly broken $A_4$ terms in the scalar potential does allow for a fit of quark mass matrices. Moreover, the result is consistent with $m_h=125\textrm{GeV}$ and the $h \rightarrow WW, ZZ$ signal. We also checked numerically that, for each point that passes all the constraints, the minimum is a global minimum of the potential.Comment: 21 pages, 10 Figures in PDF. Minor changes; matches version to be publishe

Multi-Higgs doublet models: the Higgs-fermion couplings and their sum rules

This is the second of a series of papers that explores the physical parameterization, sum rules and unitarity bounds arising from a non-minimal scalar sector of the Standard Model (SM) that consists of N Higgs doublets. In this paper, we focus on the structure and implication of the Yukawa interactions that couple the N scalar doublets to the SM fermions. We employ the charged Higgs basis, which is defined as the basis of scalar fields such that the neutral scalar field vacuum expectation value resides entirely in one of the N scalar doublet fields, and the charged components of the remaining N-1 scalar doublet fields are the physical (mass-eigenstate) charged Higgs fields. Based on the structure of the Yukawa Lagrangian of the model (and as a consequence of tree-level unitarity), one may deduce numerous sum rules, several of which have not appeared previously in the literature. These sum rules can be used to uncover intimate relations between the structure of the Higgs-fermion couplings and the scalar/gauge couplings. In particular, we show that the approximate alignment limit, in which the W+W- and ZZ couplings to the observed Higgs boson are approximately SM-like, imposes significant constraints on the Higgs-fermion couplings.Comment: 24 pages, 2 figures, 4 tables, uses jheppub.sty. Two typographical errors corrected, one clarification added and one reference updated in v

Constraining multi-Higgs flavour models

To study a flavour model with a non-minimal Higgs sector one must first define the symmetries of the fields; then identify what types of vacua exist and how they may break the symmetries; and finally determine whether the remnant symmetries are compatible with the experimental data. Here we address all these issues in the context of flavour models with any number of Higgs doublets. We stress the importance of analysing the Higgs vacuum expectation values that are pseudo-invariant under the generators of all subgroups. It is shown that the only way of obtaining a physical CKM mixing matrix and, simultaneously, non-degenerate and non-zero quark masses is requiring the vacuum expectation values of the Higgs fields to break completely the full flavour group, except possibly for some symmetry belonging to baryon number. The application of this technique to some illustrative examples, such as the flavour groups Delta(27), A4 and S3, is also presented.Comment: 13 pages, 3 figures, title and abstract changed, comments and references added; matches version to appear in The European Physical Journal

Fetal axillary lymphangioma

Lymphangioma is a rare congenital malformation of the lymphatic system that occur in 1 per 6000 live births. The most common site of lymphangioma is the neck (also named cystic hygroma), accounting for 75% of the cases, and it is strongly related to aneuploidies. Axillary location is very rare and appears not to be associated with chromosomal abnormalities. Tumor growth, fetal anemia secondary to intralesional bleeding, hydrops fetalis and shoulder dystocia are possible obstetric complications of this condition. The prognosis is generally good in the absence of abnormal karyotype, fetal hydrops or extension of the lymphangioma to adjacent tissues. Surgical excision or sclerotherapy are the main treatment choices. The authors present a case of a right fetal axillary lymphangioma and review the literature

Fingerprinting the Type-Z three Higgs doublet models

There has been great interest in a model with three Higgs doublets in which fermions with a particular charge couple to a single and distinct Higgs field. We study the phenomenological differences between the two common incarnations of this so-called Type-Z 3HDM. We point out that the differences between the two models arise from the scalar potential only. Thus we focus on observables that involve the scalar self-couplings. We find it difficult to uncover features that can uniquely set apart the $Z_3$ variant of the model. However, by studying the dependence of the trilinear Higgs couplings on the nonstandard masses, we have been able to isolate some of the exclusive indicators for the $Z_2\times Z_2$ version of the Type-Z 3HDM. This highlights the importance of precision measurements of the trilinear Higgs couplings.Comment: 15 pages, 4 captioned figure

URBSOIL-LISBON-Geoquímica dos solos urbanos de Lisboa: caracterização e cartografia, suporte para futuros estudos de saúde humana: resultados preliminares

A Geologia, e em especial a Geoquímica em ambiente urbano, têm-se revelado ferramentas essenciais não só no estudo dos materiais naturais neste ambiente, como na ligação entre a Geologia e a acção antrópica. Este estudo, com uma metodologia que usa vários meios de amostragem, pretende avaliar quais os elementos químicos que podem intervir num contexto de interacção em que as crianças são tomadas como alvo principal. Os primeiros resultados sobre concentrações de elementos químicos para os solos urbanos de Lisboa apontam para uma exposição esparsa na cidade de alguns dos elementos químicos inorgânicos, mas havendo por vezes um zonamento por tipologia de local ou de elemento químico. Foram definidos quatro grupos de pontos de amostragem consoante o tipo de uso, e escolhidos para uma análise mais próxima alguns elementos considerados tendencialmente de input antrópico e que se relacionam com a saúde humana.