553 research outputs found
A Simple Method to detect spontaneous CP Violation in multi-Higgs models
For models with several Higgs doublets we present an alternative method to
the one proposed by Branco, Gerard and Grimus, in 1984, to check whether or not
CP is spontaneously violated in the Higgs potential. The previous method is
powerful and rigorous. It requires the identification of a matrix
corresponding to a symmetry of the Lagrangian and verifying a simple relation
involving the vacuum expectation values. The nonexistence of such a matrix
signals spontaneous CP violation. However, as the number of Higgs doublets
increases, finding such a matrix may not be straightforward and it may turn
out to be easier to analyse the potential by going to the so-called Higgs
basis. The transformation to the Higgs basis is straightforward once the vacuum
expectation values are known. The method proposed in this work is also powerful
and rigorous and can be particularly useful to analyse models with more than
two Higgs doublets and with continuous symmetries.Comment: 9 pages, no figures. v2: minor changes, matching JHEP versio
Implications of symmetries in the scalar sector
Symmetries play a very important r\^ole in Particle Physics. In extended
scalar sectors, the existence of symmetries may permit the models to comply
with the experimental constraints in a natural way, and at the same time reduce
the number of free parameters. There is a strong interplay among internal
symmetries of the scalar potential, its CP properties and mass degeneracies of
the physical scalars. Some of these aspects were discussed in this talk.Comment: 8 pages, to be published in the Proceedings of DISCRETE2018: 6th
Symposium on Prospects in the Physics of Discrete Symmetries, 26-30 Nov 2018.
Vienna, Austri
Spontaneous symmetry breaking in the -symmetric scalar sector
We present a detailed study of the vacua of the -symmetric
three-Higgs-doublet potential, specifying the region of parameters where these
minimisation solutions occur. We work with a CP conserving scalar potential and
analyse the possible real and complex vacua with emphasis on the cases in which
the CP symmetry can be spontaneously broken. Results are presented both in the
reducible-representation framework of Derman, and in the
irreducible-representation framework. Mappings between these are given. Some of
these implementations can in principle accommodate dark matter and for that
purpose it is important to identify the residual symmetries of the potential
after spontaneous symmetry breakdown. We are also concerned with constraints
from vacuum stability.Comment: 37 pages. v2: Minor changes in the references, matches published
version. v3: Table 6 corrected: two additional cases conserve CP. Related
discussion adapted. Version consistent with JHEP Erratu
Symmetries and Mass Degeneracies in the Scalar Sector
We explore some aspects of models with two and three SU(2) scalar doublets
that lead to mass degeneracies among some of the physical scalars. In Higgs
sectors with two scalar doublets, the exact degeneracy of scalar masses,
without an artificial fine-tuning of the scalar potential parameters, is
possible only in the case of the inert doublet model (IDM), where the scalar
potential respects a global U(1) symmetry that is not broken by the vacuum. In
the case of three doublets, we introduce and analyze the replicated inert
doublet model, which possesses two inert doublets of scalars. We then
generalize this model to obtain a scalar potential, first proposed by Ivanov
and Silva, with a CP4 symmetry that guarantees the existence of pairwise
degenerate scalar states among two pairs of neutral scalars and two pairs of
charged scalars. Here, CP4 is a generalized CP symmetry with the property that
is the identity operator only for integer values that are
multiples of 4. The form of the CP4-symmetric scalar potential is simplest when
expressed in the Higgs basis, where the neutral scalar field vacuum expectation
value resides entirely in one of the scalar doublet fields. The symmetries of
the model permit a term in the scalar potential with a complex coefficient that
cannot be removed by any redefinition of the scalar fields within the class of
Higgs bases (in which case, we say that no real Higgs basis exists). A striking
feature of the CP4-symmetric model is that it preserves CP even in the absence
of a real Higgs basis, as illustrated by the cancellation of the contributions
to the CP violating form factors of the effective ZZZ and ZWW vertices.Comment: 52 pages, 2 figures, second revised version with new material, as
published by JHE
Spontaneous symmetry breaking in three-Higgs-doublet -symmetric models
The talk summarises work done by the authors consisting of a detailed study
of the possible vacua in models with three Higgs doublets with symmetry
and without explicit CP violation. Different vacua require special regions of
the parameter space which were analysed in our work. We establish the
possibility of spontaneous CP violation in this framework and we also show
which complex vacua conserve CP. In our work we discussed constraints from
vacuum stability. The results presented here are relevant for model building.Comment: 11 pages, no figures. Prepared for the proceedings of DISCRETE2016:
the Fifth Symposium on Prospects in the Physics of Discrete Symmetries, 28
November-3 December 2016, University of Warsaw, Poland, to appear in the
Journal of Physics: Conference Series (JPCS
Limb-girdle muscular dystrophy in a Portuguese patient caused by a mutation in the telethonin gene
Limb-girdle muscular dystrophy 2G is caused by mutations in the telethonin (TCAP) gene in chromosome 17q11-12. This rare form of hereditary muscle disease was originally described in Brazilian patients and was recently identified in Chinese and Moldavian patients. We present the first Portuguese patient with a limb-girdle muscular dystrophy caused by a mutation in the TCAP gene. A Caucasian male, 50 years old, presented in his early twenties, slowly progressive weakness in upper and lower limbs. Neurologic examination revealed severe atrophy and weakness in the muscles of the arms, thighs and legs' anterior compartment. Muscle MRI of the thighs and legs revealed severe atrophy of all the muscles of the thighs and legs' anterolateral compartment, in a symmetrical way. Molecular studies identified the homozygous c.157C > T (p.Gln53X) mutation in exon 2 of the TCAP gene, already described in Brazilian patients
Comportamento dinâmico de pontes pedonais de madeira
Na Parte 2 do Eurocódigo 5 é proposto, para tipologias correntes, um processo simplificado de verificação do estado-limite de vibração para pontes de madeira sujeitas à acção de grupos de peões, o qual utiliza estimativas do valor máximo da aceleração no tabuleiro.
Neste trabalho procede-se à comparação entre os valores determinados por esse método e os obtidos por análise dinâmica de modelos numéricos de Elementos Finitos, sob a acção de grupos de peões de dimensão e frequência de passada variáveis.
Descrevem-se ainda os modelos probabilísticos utilizados na geração do carregamento dinâmico correspondente a estes grupos
Reverse logistics for recycling: the customer service determinants
Customer service is a central concern in the logistics practice and a study topic in the forward logistics research. This article investigates the elements of customer service and their importance in reverse logistics for recycling. Since consumer is the first intervenient in any reverse system that aims to recycle household residues, the provision of an adequate customer service gains an increased importance. Applying multivariate statistical methods (exploratory factor analysis, confirmatory factor analysis and discriminant analysis) to the data from a sample of 267 Portuguese citizens, this study identifies the levels of customer service in this reverse logistics chain and evaluates their relative importance in achieving consumers' participation. The study finds that, as in forward logistics, the customer service in reverse channels for recycling also has a hard and a soft level, being the former more important than the later. The results of this research suggest important guidelines to improve such a complex logistics service
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