CP violation conditions in N-Higgs-doublet potentials

Conditions for CP violation in the scalar potential sector of general N-Higgs-doublet models are analyzed from a group theoretical perspective. For the simplest two-Higgs-doublet model potential, a minimum set of conditions for explicit and spontaneous CP violation is presented. The conditions can be given a clear geometrical interpretation in terms of quantities in the adjoint representation of the basis transformation group for the two doublets. Such conditions depend on CP-odd pseudoscalar invariants. When the potential is CP invariant, the explicit procedure to reach the real CP-basis and the explicit CP transformation can also be obtained. The procedure to find the real basis and the conditions for CP violation are then extended to general N-Higgs-doublet model potentials. The analysis becomes more involved and only a formal procedure to reach the real basis is found. Necessary conditions for CP invariance can still be formulated in terms of group invariants: the CP-odd generalized pseudoscalars. The problem can be completely solved for three Higgs-doublets.

Angular momentum and energy-momentum densities as gauge currents

If we replace the general spacetime group of diffeomorphisms by transformations taking place in the tangent space, general relativity can be interpreted as a gauge theory, and in particular as a gauge theory for the Lorentz group. In this context, it is shown that the angular momentum and the energy-momentum tensors of a general matter field can be obtained from the invariance of the corresponding action integral under transformations taking place, not in spacetime, but in the tangent space, in which case they can be considered as gauge currents.

Structure formation in the presence of dark energy perturbations

We study non-linear structure formation in the presence of dark energy. The influence of dark energy on the growth of large-scale cosmological structures is exerted both through its background effect on the expansion rate, and through its perturbations. In order to compute the rate of formation of massive objects we employ the spherical collapse formalism, which we generalize to include fluids with pressure. We show that the resulting non-linear evolution equations are identical to the ones obtained in the pseudo-Newtonian approach to cosmological perturbations, in the regime where an equation of state serves to describe both the background pressure relative to density, and the pressure perturbations relative to the density perturbations. We then consider a wide range of constant and time-dependent equations of state (including phantom models) parametrized in a standard way, and study their impact on the non-linear growth of structure. The main effect is the formation of dark energy structure associated with the dark matter halo: non-phantom equations of state induce the formation of a dark energy halo, damping the growth of structures; phantom models, on the other hand, generate dark energy voids, enhancing structure growth. Finally, we employ the Press-Schechter formalism to compute how dark energy affects the number of massive objects as a function of redshift (number counts).

Axial-vector torsion and the teleparallel Kerr spacetime

In the context of the teleparallel equivalent of general relativity, we obtain the tetrad and the torsion fields of the stationary axisymmetric Kerr spacetime. It is shown that, in the slow rotation and weak-field approximations, the axial-vector torsion plays the role of the gravitomagnetic component of the gravitational field, and is thus responsible for the Lense-Thirring effect.

On the birth of a closed hyperbolic universe

We clarify and develop the results of a previous paper on the birth of a closed universe of negative spatial curvature and multiply connected topology. In particular we discuss the initial instanton and the second topology change in more detail, This is followed by a short discussion of the results.

Lorentz Connections and Gravitation

The different roles played by Lorentz connections in general relativity and in teleparallel gravity are reviewed. Some of the consequences of this difference are discussed.

Some interesting features of new massive gravity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Charged three-body system with arbitrary masses near conformal invariance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Production of biodiesel by esterification of palmitic acid over mesoporous aluminosilicate Al-MCM-41

Biodiesel has been obtained by esterification of palmitic acid with methanol, ethanol and isopropanol in the presence of Al-MCM-41 mesoporous molecular sieves with Si/Al ratios of 8.16 and 32. The catalytic acids were synthesized at room temperature and characterized by atomic absorption spectrometry (AAS), thermal analysis (TG/DTA), X-ray diffraction (XRD), nitrogen absorption (BET/BJH), infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The reaction was carried out at 130 degrees C whilst stirring at 500 rpm, with an alcohol/acid molar ratio of 60 and 0.6 wt% catalyst for 2 h. The alcohol reactivity follows the order methanol > ethanol > isopropanol. The catalyst Al-MCM-41 with ratio Si/Al = 8 produced the largest conversion values for the alcohols studied. The data followed a rather satisfactory approximation to first-order kinetics. (C) 2008 Elsevier Ltd. All rights reserved.

Comparação de métodos de adaptabilidade e estabilidade relacionados à produtividade de grãos de cultivares de milho

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of desflurane, sevoflurane and isoflurane on pulmonary shunt in dogs during spontaneous ventilation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Histopatologia endometrial e fertilidade de éguas portadoras de pneumovagina tratadas através das técnicas cirúrgicas de Caslick ou Pouret

Com o objetivo de avaliar a evolução da condição endometrial após as cirurgias de Caslick e Pouret, empregou-se cada uma destas técnicas em um grupo de sete éguas, com histórico de subfertilidade e portadoras de pneumovagina, que justificassem, por sua conformação vulvar, a aplicação destas cirurgias. A avaliação da condição endometrial foi feita através dos exames de biópsia do endométrio, realizados imediatamente antes da cirurgia e aos 15 e 60 dias de pós-operatório e ainda pela verificação das taxas de fertilidade em ambos os grupos, durante a estação reprodutiva do ano subseqüente. A comparação dos resultados dos exames do período pós em relação ao pré-operatório evidenciou modificações histopatológicas suficientemente sutis para não levar a mudanças na classificação endometrial durante o período de observação, porém a melhora obtida nas taxas de fertilidade nos grupos experimentais permitiram concluir que as cirurgias corretivas de Caslick e Pouret proporcionaram melhora do desempenho reprodutivo de éguas portadoras de pneumovagina.

GHOST POLES IN THE NUCLEON PROPAGATOR - VERTEX CORRECTIONS AND FORM-FACTORS

Vertex corrections are taken into account in the Schwinger-Dyson equation for the nucleon propagator in a relativistic field theory of fermions and mesons. The usual Hartree-Fock approximation for the nucleon propagator is known to produce the appearance of complex (ghost) poles which violate basic theorems of quantum field theory. In a theory with vector mesons there are vertex corrections that produce a strongly damped vertex function in the ultraviolet. One set of such corrections is known as the Sudakov form factor in quantum electrodynamics. When the Sudakov form factor generated by massive neutral vector mesons is included in the Hartree-Fock approximation to the Schwinger-Dyson equation for the nucleon propagator, the ghost poles disappear and consistency with basic requirements of quantum field theory is recovered.

Maximum number of flux lines inside columnar defects

We set new limits for the maximum number of fluxons trapped inside columnar defects, for both cases of metallic and insulated cores. We show that the saturation limit predicted by the Mkrtchyan and Shmidt theory is just a first approximation to our results, because it does not consider the presence of the remaining flux lines exterior to the defects.