Primordial Black Holes from Higgs Vacuum Instability: Avoiding Fine-tuning through an Ultraviolet Safe Mechanism

We have recently proposed the idea that dark matter in our universe is formed by primordial black holes generated by Standard Model Higgs fluctuations during inflation and thanks to the fact that the Standard Model Higgs potential develops an instability at a scale of the order of $10^{11}$ GeV. In this sense, dark matter does not need any physics beyond the Standard Model, although the mechanism needs fine-tuning to avoid the overshooting of the Higgs into the dangerous AdS vacuum. We show how such fine-tuning can be naturally avoided by coupling the Higgs to a very heavy scalar with mass $\gg 10^{11}$ GeV that stabilises the potential in the deep ultraviolet, but preserving the basic feature of the mechanism which is built within the Standard Model.Comment: 5 pages, 4 figure

An educational tool to assist the design process of switched reluctance machines

The design of electric machines is a hot topic in the syllabuses of several undergraduate and graduate courses. With the development of hybrid and electrical vehicles, this subject is gaining more popularity, especially in electrical engineering courses. This paper presents a computeraided educational tool to guide engineering students in the design process of a switched reluctance machine (SRM). A step-by-step design procedure is detailed and a user guide interface (GUI) programmed in the Matlab® environment developed for this purpose is shown. This GUI has been proved a useful tool to help the students to validate the results obtained in their lecture assignments, while aiding to achieve a better understanding of the design process of electric machines. A validation of the educational tool is done by means of finite element method (FEM) simulations.Postprint (author's final draft

Art

The earliest artistic manifestations in Malta date to prehistoric times. This is testified by a rich archaeological heritage consisting of a variety of decorated clay and stone artifacts and a series of impressive megalithic structures. The potter's craft developed into an expression of cultural vitality materialised through a series of patterns and decorations that reflect successive aesthetic requirements. The Impressed Ware of the early neolithic farmers of the Gliar Dalam phase (5000-4500 B.C.) was superseded by the prosaic forms of the Grey Skorba phase (4500-4400 B.C.) and enlivened by a bright red slip in the course of the so called Red Skorba phase (4400-4100 B.C.). Meanwhile man discovered the art of modelling anthropomorphic figurines. However it was during the Temple Period (4100-2500 B.C.) that prehistoric man in Malta poured forth an extraordinary civilising energy that took the contours of greatness.peer-reviewe

Respuesta tensiomiográfica aguda asociada al entrenamiento muscular con sobregarga excéntrica en jóvenes futbolistas de élite

El objetivo principal de este estudio es el de medir la respuesta tensiomiográfica aguda en jóvenes futbolistas de élite tras un entrenamiento de fuerza enfocado a la musculatura de la rodilla, con sobrecarga excéntrica. Para ello, un total de dieciocho jugadores de fútbol (edad = 17 ± 1.2 años; altura = 178 ± 2,34 cm; peso = 71 ± 4.56 kg; IMC = 19.12 ± 2.45) pertenecientes a la cantera de un equipo profesional de fútbol de la liga española realizaron tres sesiones de entrenamiento: una situación control, con un calentamiento en cicloergómetro (CON), un entrenamiento de fuerza con sobrecarga excéntrica, mediante tecnología Yo-Yo®, focalizado en la musculatura isquiosural (EXP-ISQ) y un entrenamiento de las mismas características que el anterior, pero enfocado a la musculatura cuadricipital (EXP-Q). Inmediatamente después de cada una de las sesiones, se realizó una tensiomiografía (TMG), analizando una curva desplazamiento-tiempo sobre el vasto medial (VM) tras EXP-Q y sobre el bíceps femoral (BF) tras EXP-ISQ. Los resultados reflejaron un descenso de todos los tiempos de contracción, resultando significativos sólo Tc (p<0.01), Ts (p<0.01) y Td (p=0.001) para el VM y en Tr (p<0.05) y Td (p<0.05) en el caso del BF. En base a estos datos podemos concluir que la carga planificada para el entrenamiento permite una activación de la musculatura implicada, no desarrollándose en ningún caso una respuesta tensiomiográfica asociada a fatiga muscular local

Los mosaicos de la villa romana de Torre-La Cruz (Villajoyosa, Alicante)

Se estudian varios fragmentos de mosaico, algunos inéditos, pertenecientes a la zona de los Balnea de la villa bajo imperial de Torre-La Cruz (Villajoyosa, Alicante). Se ofrece su despcripción completa, acompañada de los primeros calcos realizados directamente sobre las piezas originales. Este trabajo supone una interpretación de la distribución espacial de cada fragmento, así como de la cronología de los dos niveles superpuestos de estos balnea y de sus mosaicos

Gauge-Independent Scales Related to the Standard Model Vacuum Instability

The measured (central) values of the Higgs and top quark masses indicate that the Standard Model (SM) effective potential develops an instability at high field values. The scale of this instability, determined as the Higgs field value at which the potential drops below the electroweak minimum, is about $10^{11}$ GeV. However, such a scale is unphysical as it is not gauge-invariant and suffers from a gauge-fixing uncertainty of up to two orders of magnitude. Subjecting our system, the SM, to several probes of the instability (adding higher order operators to the potential; letting the vacuum decay through critical bubbles; heating up the system to very high temperature; inflating it) and asking in each case physical questions, we are able to provide several gauge-invariant scales related with the Higgs potential instability.Comment: 44 pages, 9 figure

La función crítica en el acto educativo : fundamentación antropológica

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Performance evaluation of space-time block coding using a realistic mobile radio channel

This paper presents a performance evaluation of space-time block coding (STBC) employing a realistic mobile radio channel model in macrocellular and urban environments. The bit error rate (BER) is computed by Monte-Carlo simulations in the down-link to evaluate its sensitivity to channel correlation. We consider a horizontal uniform linear array at the base station (BS) formed by up to four antenna elements, and one and two uncorrelated antenna elements at the mobile station (MS). The channel model includes the probability density function (pdf) of the azimuth and delay of the impinging waves and their expected power conditioned on the azimuth and delay. The statistical properties of the model are extracted from macrocellular measurements made in urban environments. Simulation results show that the use of STBC can provide significant gains with acceptable sensitivity to the channel correlation under realistic conditions.Peer ReviewedPostprint (published version

Optimization of modular wiring harnesses by means of regression models for temperature prediction of wire bundles

Automotive wiring harnesses have become heavier and more complex due to their increasing number of electrical components. It is now desired to reduce their mass of copper. For this purpose, experimentation can be partially replaced by simulation, but it is still impossible to exhaustively simulate all of the combinations of modular wiring harness. This proposed approach consists of carrying out simulations using the FEM method and using their results to create regression models. Polynomial formulae can give the same information as simulations within a clearly reduced time and satisfying accuracy. An optimization algorithm introduced in this study will use them to assign new cable cross-sections of harnesses considering their currents and the ambient temperature.Postprint (author's final draft