Leptogenesis, Dark Matter and Higgs Phenomenology at TeV

We propose an interesting model of neutrino masses to realize leptogenesis and dark matter at the TeV scale. A real scalar is introduced to naturally realize the Majorana masses of the right-handed neutrinos. We also include a new Higgs doublet that contributes to the dark matter of the universe. The neutrino masses come from the vacuum expectation value of the triplet Higgs scalar. The right-handed neutrinos are not constrained by the neutrino masses and hence they could generate leptogenesis at the TeV scale without subscribing to resonant leptogenesis. In our model, all new particles could be observable at the forthcoming Large Hardon Collider or the proposed future International Linear Collider.Comment: 7 pages, 3 figures. References added. Accepted by NP

Fermion Masses and Mixings in a S4 Based Model

It has been recently claimed that the symmetry group S4 yields to the Tri-bimaximal neutrino mixing in a "natural" way from the group theory point of view. Approving of this feature as an indication, we build a supersymmetric model of lepton and quark masses based on this family symmetry group. In the lepton sector, a correct mass hierarchy among the charged leptons is achieved together to a neutrino mass matrix which can be diagonalized by the Tri-bimaximal pattern. Our model results to be phenomenologically unequivalent with respect to other proposals based on different flavour groups but still predicting the Tri-bimaximal mixing. In the quark sector a realistic pattern for masses and mixing angles is obtained. The flavour structures of the mass matrices in both the sectors come from the spontaneously symmetry breaking of S4, due to several scalar fields, which get non-zero vacuum expectation values. A specific vacuum alignment is required and it is shown to be a natural results of the minimization of the scalar potential and, moreover, to be stable under the corrections from the higher order terms.Comment: 25 pages, LaTeX; added references and minor correctio

Electroweak Symmetry Breaking induced by Dark Matter

The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of dark matter (DM) are currently among the most important issues in high energy physics. Since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet. The coupling of the latter with the Standard Model Higgs doublet breaks the electroweak symmetry at one-loop, "a la Coleman-Weinberg". The abundance of dark matter, the breaking of the electroweak symmetry and the constraints from electroweak precision measurements can all be accommodated by imposing an (exact or approximate) custodial symmetry.Comment: 4 pages, no figure, one tabl

Non-decoupling effects in supersymmetric Higgs sectors

A wide class of Higgs sectors is investigated in supersymmetric standard models. When the lightest Higgs boson (h) looks the standard model one, the mass (m_h) and the triple Higgs boson coupling (the hhh coupling) are evaluated at the one-loop level in each model. While m_h is at most 120-130 GeV in the minimal supersymmetric standard model (MSSM), that in models with an additional neutral singlet or triplet fields can be much larger. The hhh coupling can also be sensitive to the models: while in the MSSM the deviation from the standard model prediction is not significant, that can be 30-60 % in some models such as the MSSM with the additional singlet or with extra doublets and charged singlets. These models are motivated by specific physics problems like the mu-problem, the neutrino mass, the scalar dark matter and so on. Therefore, when h is found at the CERN Large Hadron Collider, we can classify supersymmetric models by measuring m_h and the hhh coupling accurately at future collider experiments.Comment: 16pages, 6figures. To be published in Physics Letters

Biblioteca Universitaria: una década de evolución editorial

Having reached ten years of existence of the New Series of Biblioteca Universitaria a review is made of its trajectory, contents as well as of the editorial work performed which increased diffusion and quality of the journal not only in terms of the editorial criteria added but also in those related to graphical and editorial design. Biblioteca Universitaria is a technical-professional journal specialized in Library and Information Science and published by the General Directorate for Libraries (DGB) of the National Autonomous University of Mexico (UNAM)

Tri-Bimaximal Neutrino Mixing from Discrete Symmetry in Extra Dimensions

We discuss a particularly symmetric model of neutrino mixings where, with good accuracy, the atmospheric mixing angle theta_{23} is maximal, theta_{13}=0 and the solar angle satisfies sin^2(theta_{12})=1/3 (Harrison-Perkins-Scott (HPS) matrix). The discrete symmetry A_4 is a suitable symmetry group for the realization of this type of model. We construct a model where the HPS matrix is exactly obtained in a first approximation without imposing ad hoc relations among parameters. The crucial issue of the required VEV alignment in the scalar sector is discussed and we present a natural solution of this problem based on a formulation with extra dimensions. We study the corrections from higher dimensionality operators allowed by the symmetries of the model and discuss the conditions on the cut-off scales and the VEVs in order for these corrections to be completely under control. Finally, the observed hierarchy of charged lepton masses is obtained by assuming a larger flavour symmetry. We also show that, under general conditions, a maximal theta_{23} can never arise from an exact flavour symmetry.Comment: 24 pages, 1 figure, misprints corrected and references adde

TÉCNICAS Y MÉTODOS DE INVESTIGACIÓN

GUÍA DE EVALUACIÓN DEL APRENDIZAJ

Azolla y vermicomposta: Semblanza sobre la vida y obra del Dr. Roberto Quintero Lizaola

La presente reseña es un simbólico homenaje post mortem que la Sociedad Mexicana de la Ciencia del Suelo (SMCS) A.C., rinde a la memoria del Dr. Roberto Quintero Lizaola. El Dr. Quintero Lizaola nació en Ameca, Jalisco, México el 5 de mayo de 1958 y falleció el 22 de Agosto de 2018 en la Ciudad de Texcoco, Estado de México. Durante su vida científica, el Dr, Quintero Lizaola se distinguió como un activo militante de la SMCS, A.C. Además de participar como ponente y coordinador de mesas de trabajo en diferentes congresos, se involucró en diferentes comisiones en beneficio de ésta. Fungió como secretario general de la SMCS, A.C. de 1991 a 1995. Igualmente, participó como miembro del Comité de Acción para el Saneamiento del Ambiente (CASA), A.C. El Dr. Quintero Lizaola centró sus investigaciones en el estudio y aplicación del hecho acuático Azolla, así como en la caracterización y uso de las vermicompostas. Su legado como investigador del suelo, queda plasmado en los anales de la SMCS, A.C

Entre amaranto y litchi: Semblanza sobre la vida y obra del Dr. Antonio Trinidad Santos.

Se puede definir al Dr. Antonio Trinidad Santos como un entusiasta investigador de los Andosoles y de su productividad agrícola. Probablemente, el maíz, amaranto y litchi fueron los cultivos a los que dedicó el mayor tiempo de su vida científica. La presente semblanza es un reconocimiento Post mortem que la Sociedad Mexicana de la Ciencia del Suelo, A.C. hace a uno de sus más distinguidos miembros, reconociendo así el legado que deja a los futuros edafólogos