Spontaneous Symmetry Breakdown and Critical Perspectives of Higgs Mechanism

The foundations of the mass generation mechanism of particles are reviewed. The Spontaneous Symmetry Breaking (SSB) process within the standard model (SM) and the minimal supersymmetric standard model (MSSM) is used to explore the present status of the Higgs Mechanism along with the constraints in detecting the Higgs particles in experiments. The possible explanations and generalizations for the case that the Higgs particles should not appear or to couple the Higgs Mechanism (because of their gravitational nature of interaction) are also iscussed in detail in view of the Higgs field gravity.Comment: 13 pages, no figures. Final version based on original to appear in the Indian Journal of Physic

Black Hole Solutions and Pressure Terms in Induced Gravity with Higgs Potential

We study the quintessential properties of the Black Hole solutions in a scalar--tensor theory of gravity with Higgs potential in view of the static and spherically symmetric line element. In view of our earlier results, Reissner--Nordstr\"om-like and Schwarzschild Black Hole solutions are derived with the introduction of a series-expansion method to solve the field equations without and with Higgs field mass. The physical consequences of the Black Hole solutions and the solutions obtained in the weak field limit are discussed in detail by the virtue of the equation-of-state parameter, the scalar-field excitations and the geodesic motion. The appearance of naked singularities is also discussed together with the dependence of Black Hole horizons on the field excitations, which are themselves dependent on pressure terms which effectively screen the mass terms. A possible connection to flat rotation curves following the interaction with the scalar field is also presented in the weak field limit of gravity, together with a discussion of dynamical effects of scalar fields and pressure terms on mass.Comment: 28 pages, 4 figures, contents and figures modified, major revision, results are unchanged, published in Classical and Quantum Gravit

The well-posedness of the Cauchy problem for self-interacting vector fields

We point out that the initial-value (Cauchy) problem for self-interactingvector fields presents the same well-posedness issues as for first-orderderivative self-interacting scalar fields (often referred to as $k$-essence).For the latter, suitable strategies have been employed in the last few years tosuccessfully evolve the Cauchy problem at the level of the infrared theory,without the need for an explicit ultraviolet completion. We argue that the verysame techniques can also be applied to self-interacting vector fields, avoidinga number of issues and "pathologies" recently found in the literature.<br

Well-posed evolution of field theories with anisotropic scaling: the Lifshitz scalar field in a black hole space-time

Partial differential equations exhibiting an anisotropic scaling between space and time -- such as those of Horava-Lifshitz gravity -- have a dispersive nature. They contain higher-order spatial derivatives, but remain second order in time. This is inconvenient for performing long-time numerical evolutions, as standard explicit schemes fail to maintain convergence unless the time step is chosen to be very small. In this work, we develop an implicit evolution scheme that does not suffer from this drawback, and which is stable and second-order accurate. As a proof of concept, we study the numerical evolution of a Lifshitz scalar field on top of a spherically symmetric black hole space-time. We explore the evolution of a static pulse and an (approximately) ingoing wave-packet for different strengths of the Lorentz-breaking terms, accounting also for the effect of the angular momentum eigenvalue and the resulting effective centrifugal barrier. Our results indicate that the dispersive terms produce a cascade of modes that accumulate in the region in between the Killing and universal horizons, indicating a possible instability of the latter.Comment: 22 pages, 8 figures, 1 table, comments are welcome

A serial multiplex immunogold labeling method for identifying peptidergic neurons in connectomes.

This is the final version of the article.Available from eLife Sciences Publications via the DOI in this record.Electron microscopy-based connectomics aims to comprehensively map synaptic connections in neural tissue. However, current approaches are limited in their capacity to directly assign molecular identities to neurons. Here, we use serial multiplex immunogold labeling (siGOLD) and serial-section transmission electron microscopy (ssTEM) to identify multiple peptidergic neurons in a connectome. The high immunogenicity of neuropeptides and their broad distribution along axons, allowed us to identify distinct neurons by immunolabeling small subsets of sections within larger series. We demonstrate the scalability of siGOLD by using 11 neuropeptide antibodies on a full-body larval ssTEM dataset of the annelid Platynereis. We also reconstruct a peptidergic circuitry comprising the sensory nuchal organs, found by siGOLD to express pigment-dispersing factor, a circadian neuropeptide. Our approach enables the direct overlaying of chemical neuromodulatory maps onto synaptic connectomic maps in the study of nervous systems.The research leading to these results received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/European Research Council Grant Agreement 260821. This project is supported by the Marie Curie ITN "Neptune", GA 317172, funded under the FP7, PEOPLE Work Programme of the European Commission

Neuronal connectome of a sensory-motor circuit for visual navigation.

This is the final version of the article. Available from eLife Sciences Publications via the DOI in this record.Animals use spatial differences in environmental light levels for visual navigation; however, how light inputs are translated into coordinated motor outputs remains poorly understood. Here we reconstruct the neuronal connectome of a four-eye visual circuit in the larva of the annelid Platynereis using serial-section transmission electron microscopy. In this 71-neuron circuit, photoreceptors connect via three layers of interneurons to motorneurons, which innervate trunk muscles. By combining eye ablations with behavioral experiments, we show that the circuit compares light on either side of the body and stimulates body bending upon left-right light imbalance during visual phototaxis. We also identified an interneuron motif that enhances sensitivity to different light intensity contrasts. The Platynereis eye circuit has the hallmarks of a visual system, including spatial light detection and contrast modulation, illustrating how image-forming eyes may have evolved via intermediate stages contrasting only a light and a dark field during a simple visual task.The research leading to these results received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/European Research Council Grant Agreement 260821

Scalar-field Pressure in Induced Gravity with Higgs Potential and Dark Matter

A model of induced gravity with a Higgs potential is investigated in detail in view of the pressure components related to the scalar-field excitations. The physical consequences emerging as an artifact due to the presence of these pressure terms are analysed in terms of the constraints parting from energy density, solar-relativistic effects and galactic dynamics along with the dark matter halos.Comment: 26 pages, 3 figures, Minor revision, Published in JHE

Conversión normalizada (SKOS) de sistemas de organización del conocimiento interoperables en la web

Este estudio examina de forma exhaustiva la literatura científica dedicada a los procesos de skosificación de vocabularios y sistemas de organización del conocimiento. Se analizan en profundidad 49 trabajos que describen y detallan la transformación de un total de 59 vocabularios controlados convencionales o SOC (Sistemas de Organización del Conocimiento) a Simple Knowledge Organization System (SKOS). Se identifican los puntos clave para hacer el análisis de metodologías de transformación de vocabularios en SKOS para la web y se comparan los estudios para determinar las aproximaciones y parámetros más recomendables para llevar a cabo estos procesos de conversión de vocabularios, cada vez más frecuentes y necesarios en la web semántica y en entornos de linked data (LD). Los resultados señalan que la mayor parte de SOC transformados son tesauros, que los formatos mayoritarios son de texto o registros bibliográficos, que el objetivo más común al cambiar a SKOS es la mejora de la interoperabilidad de los vocabularios, y que los procesos de conversión pueden agruparse mediante tres formas: scripts realizados en distintos lenguajes, transformaciones XSL y lenguajes de mapeo. Se concluye que SKOS es considerado por los autores como una buena opción para mejorar la interoperabilidad de vocabularios controlados. This paper examines exhaustively the scientific literature about skosification processes of vocabularies and knowledge organization systems (KOS). Forty nine documents that describe and detail transformation of 59 conventional controlled vocabularies or KOS to Simple Knowledge Organization System (SKOS) were analyzed. The key points for the analysis of vocabulary transformation methodologies in SKOS for the Web were identified, and studies were compared to determine the most recommendable approximations and parameters, for conversion processes of vocabularies were each time more frequent and necessary in semantic web and linked data (LD) environments. Results indicated that the majority of transformed SOCs are thesauri, that most formats were text or bibliographic records, that the most common objective in the change to SKOS was improvement of interoperability of the vocabularies and that the conversion processes could be grouped by three forms: Scripts made in different languages; XSL transformations, and mapping languages. It was concluded that SKOS is considered by the authors as a good option for improving the interoperability of controlled vocabularies