Search

Este estudio esclarece los conceptos de deuda pública cierta, respecto a la deuda contingente e identifica su impacto en la sostenibilidad de las finanzas públicas del país. Los razonamientos que se hacen acerca de la sostenibilidad de la deuda es decir, si la deuda de un país puede ser otorgada sin una gran corrección futura en el balance de ingresos y gastos, se dirigen a determinar en qué momento es apropiado para un país refinanciar y sí una reestructuración de la deuda puede ser necesaria. En la parte siguiente se realiza un análisis sobre la incertidumbre alrededor de las proyecciones de la deuda y el servicio de la deuda, la cual se relaciona con los derechos contingentes, tales como los definidos con las garantías explícitas implícitas de la deuda de los pasivos pensionales contingentes. Bajo el enfoque de los derechos contingentes en un nivel agregado, se analizan los puntos de incertidumbre mencionados, estimando el riesgo de crédito del gobierno central en este caso (probabilidad de default), evaluando los costos potenciales de las transferencias y calculando el spread sobre la deuda pública. Posteriormente se examina la estructura y operación del sistema pensional colombiano en la actualidad, evaluando múltiples factores de riesgo que afectan el escenario del sistema colombiano de pensiones tanto en el presente como en el futuro. Finalmente, con base en una gama de alternativas técnicas de valoración del riesgo y su implementación para el escenario de la seguridad social se ilustra la problemática del riesgo que encierra la deuda pensional en Colombia proyectando variables clave como: el salario, las cotizaciones, el empleo y el PIB. Con base en dichas proyecciones, se analiza el costo fiscal y la viabilidad de la garantía de pensión mínima., This study clarifies, the concepts of certain national debt with respect to the contingent debt as well as it identifies his impact in the sustainability of the public finances of the country. The reasoning that become about the sustainability of the debt, that is to say, if the debt of a country can be granted without a great future correction in the balance of income and expenses, go to determine in what moment a country is appropriate to refinance and when a reconstruction of the debt can be necessary. In the following pan, an analysis is made on the uncertainty around the projections of the debt and the service of the debt, which is related to the contingent rights, such as the defined ones with the explicit or implicit guarantees of the debt or the contingent pensionales liabilities. Under the approach of the contingent rights in a added level, the mentioned points of uncertainty are analyzed. We consider the risk of credit of the central government in this case (probability of default), evaluating the potential costs of the transferences and calculating spread on the national debt. Later it is examined the structure and operation del Colombian pensional system at the present time, evaluating multiple factors of risk that affect the scene as much of the Colombian system of pensions today as in the future. Finally, with base in a range of technical alternatives of valuation of the risk and its implementation for the scene of the social security the problematic one of the risk acquires knowledge that looks up the pensional debt in variable Colombia projecting key like: the wage, the quotations, the employment and the GDF. With base in these projections, one analyzes the fiscal cost and the viability of the guarantee of minimum pension.

We consider the version of the Zee model where both Higgs doublets couple to leptons. Within this framework we study charged Higgs decays. We focus on a model with minimal number of parameters consistent with experimental neutrino data. Using constraints from neutrino physics we (i) discuss the reconstruction of the parameter space of the model using the leptonic decay patterns of both of the two charged Higgses, $h_{1,2}^{+}\to \ell_{j}^{+}\nu_{i}$, and the decay of the heavier charged Higgs, $h_{2}^{+}\to h^{+}_{1}h^{0}$; (ii) show that the decay rate $\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i})$ in general is enhanced in comparision to the standard two Higgs doublet model while in some regions of parameter space $\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i})$ even dominates over $\Gamma(h_{1}^{+}\to \tau^{+}\nu_{i})$., Comment: 25 pages, 9 figures

En este artículo se propone la creación de ambientes virtuales en red a partir de topologías híbridas, donde la mezcla entre cliente servidor y grupos multicast, permite disminuir los cuellos de botella y balancear las cargas a la hora de transmitir y controlar la información en la red. Uno de los factores más importantes en la creación de un ambiente virtual en red, es la topología de red a utilizar. Entre las topologías de red utilizadas con mayor frecuencia, se encuentran la cliente servidor y la “par-a-par” (del inglés “peer-to-peer”), generalmente utilizando grupos multicast. Ambas topologías tienen sus ventajas y desventajas. Así, mientras el cliente servidor ofrece un muy buen grado de consistencia, la utilización de grupos multicast sacrifica dicha consistencia a favor de la velocidad, y reducen el número de mensajes que viajan por la red. El uso de una topología híbrida, como la propuesta en este artículo, puede ayudar a balancear las desventajas que presentan los esquemas puros cuando son implementados de manera individual.

The Higgs potential and the mass spectrum of the N=1 supersymmetric extension of a recently proposed one-family model based on the local gauge group $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$, which is a subgroup of the electroweak-strong unification group $E_6$, is analyzed. In this model the slepton multiplets play the role of the Higgs scalars and no Higgsinos are needed, with the consequence that the sneutrino, the selectron and six other sleptons play the role of the Goldstone bosons. We show how the $\mu$ problem is successfully addressed in the context of this model which also predicts the existence of a light CP-odd scalar., Comment: REVTeX 4, 10 pages. Included discussions about constraints coming from the rho-parameter and from Muon (g-2). References added. Version to appear in Phys. Rev. D

A Majorana neutrino is characterized by just one flavor diagonal electromagnetic form factor: the anapole moment, that in the static limit corresponds to the axial vector charge radius . Experimental information on this quantity is scarce, especially in the case of the tau neutrino. We present a comprehensive analysis of the available data on the single photon production process $e^+ e^- -> \nu \bar\nu \gamma$ off Z-resonance, and we discuss the constraints that these measurements can set on for the tau neutrino. We also derive limits for the Dirac case, when the presence of a vector charge radius is allowed. Finally, we comment on additional experimental data on $\nu_\mu$ scattering from the NuTeV, E734, CCFR and CHARM-II collaborations, and estimate the limits implied for and for the muon neutrino., Comment: 20 pages, 2 eps figures. CCFR data included in the analysis. Conclusion unchanged

We study the decays of the lightest top squark in supergravity models with and without R-parity. Using the simplest model with an effective explicit bilinear breaking of R-parity and radiative electroweak symmetry breaking we show that, below the threshold for decays into charginos $\tilde t_1\to c\chi^+_1$, the lightest stop decays mainly into third generation fermions, $\tilde t_1\to b\tau$ instead of the R-parity conserving mode $\tilde t_1\to c\chi^0_1$, even for tiny tau--neutrino mass values. Moreover we show that, even above the threshold for decays into charginos, the decay $\tilde t_1\to b\tau$ may be dominant. We study the role played by the universality of the boundary conditions on the soft supersymmetry breaking terms. This new decay mode $\tilde t_1\to b\tau$ as well as the cascades originated by the conventional $\tilde t_1\to c\chi^0_1$ decay followed by the R-parity violating neutralino decays can provide new signatures for stop production at LEP and the Tevatron., Comment: Latex, 27 pages, including 11 figures. Version to be published in Nucl. Phys. B

We perform a careful study of the neutral scalar sector of a model which includes a singlet, a doublet, and a triplet scalar field under $SU(2)$. This model is motivated by neutrino physics, since it is simply the most general version of the seesaw model of neutrino mass generation through spontaneous violation of lepton number. The neutral Higgs sector contains three CP-even and one massive CP-odd Higgs boson $A$, in addition to the massless CP-odd majoron $J$. The weakly interacting majoron remains massless if the breaking of lepton number symmetry is purely spontaneous. We show that the massive CP-odd Higgs boson may invisibly decay to three majorons, as well as to a CP-even Higgs $H$ boson plus a majoron. We consider the associated Higgs production $e^+e^- \to Z \to H A$ followed by invisible decays $A \to JJJ$ and $H \to JJ$ and derive the corresponding limits on masses and coupling that follow from LEP I precision measurements of the invisible Z width. We also study a novel $b \bar{b} b\bar{b}p\!\!\!/_T$ signal predicted by the model, analyse the background and perform a Monte-Carlo simulation of the signal in order to illustrate the limits on Higgs boson mass, couplings and branching ratios that follow from that., Comment: 21 pages, 7 figures, latex