Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment

In this paper, we review theoretical and experimental research on rare region effects at quantum phase transitions in disordered itinerant electron systems. After summarizing a few basic concepts about phase transitions in the presence of quenched randomness, we introduce the idea of rare regions and discuss their importance. We then analyze in detail the different phenomena that can arise at magnetic quantum phase transitions in disordered metals, including quantum Griffiths singularities, smeared phase transitions, and cluster-glass formation. For each scenario, we discuss the resulting phase diagram and summarize the behavior of various observables. We then review several recent experiments that provide examples of these rare region phenomena. We conclude by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative Ising chain fixed, references added, v3: final version as publishe

Distrito de transferencia de tecnología - Pamplona : resumen operativo gerencial y programación

El resumen operativo gerencial es una herramienta eficaz para vincular la etapa de formulación de un proyecto con la ejecución del mismo. Se elabora en case a las directrices establecidas en el documento del proyecto y constituye un instrumento operativo ajustado alas condiciones imperantes en el área de influencia al momento de la ejecución, facilitando el seguimiento y la evaluación. Además presenta una visión de conjunto clara y cuantificada de los objetivos y metas que se persiguen, favoreciendo el logro de una adecuada gestión. También es útil para formular proyectos bien diseñados, realistas y evaluables simplificando el proceso de detectar errores de diseño. En este documento se presenta un resumen operativo gerencial y el plan de implementación de los proyectos que conforman el distrito de transferencia tecnológica - Pamplona. A saber: fortalecimiento al sistema de transferencia de tecnología; comercialización; alimentación y nutriciónInstituto Interamericano de Cooperación para la Agricultura - IIC

Holographic c-theorems in arbitrary dimensions

We re-examine holographic versions of the c-theorem and entanglement entropy in the context of higher curvature gravity and the AdS/CFT correspondence. We select the gravity theories by tuning the gravitational couplings to eliminate non-unitary operators in the boundary theory and demonstrate that all of these theories obey a holographic c-theorem. In cases where the dual CFT is even-dimensional, we show that the quantity that flows is the central charge associated with the A-type trace anomaly. Here, unlike in conventional holographic constructions with Einstein gravity, we are able to distinguish this quantity from other central charges or the leading coefficient in the entropy density of a thermal bath. In general, we are also able to identify this quantity with the coefficient of a universal contribution to the entanglement entropy in a particular construction. Our results suggest that these coefficients appearing in entanglement entropy play the role of central charges in odd-dimensional CFT's. We conjecture a new c-theorem on the space of odd-dimensional field theories, which extends Cardy's proposal for even dimensions. Beyond holography, we were able to show that for any even-dimensional CFT, the universal coefficient appearing the entanglement entropy which we calculate is precisely the A-type central charge.Comment: 62 pages, 4 figures, few typo's correcte

Genotype by environment interaction and productive potential of 25 starch maize assessed at the Tayacaja Province, Peru

La interacción genotipo por ambiente (IGA) representa el principal obstáculo en la selección de los genotipos promisorios para diversos ambientes. El objetivo de esta investigación fue evaluar la IGA y el potencial productivo de 25 variedades de maíz amiláceo, utilizando el modelo de efectos principales aditivos e interacción multiplicativa (AMMI). Se utilizó la información generada en cinco ensayos establecidos en diferentes localidades de la provincia de Tayacaja, Huancavelica, Perú, en el ciclo del cultivo 2018–2019, bajo un diseño alfa látice 5x5, con tres repeticiones y unidades experimentales de dos hileras de 4 m de longitud, con arreglos espaciales de 0,80 m entre hileras y 0,20 m entre puntos de siembra. El potencial productivo de los cultivares se midió a través del rendimiento de grano, ajustado a 15 % de humedad. Definida la IGA, se realizó el análisis multivariado, para obtener los valores singulares de los primeros términos significativos del modelo para genotipos y ambientes. La IGA resultó altamente significativa y explicó alrededor del 14 % de la variación fenotípica del rendimiento, mostrando algunas variedades con adaptación específica y otras con amplia adaptación a los ambientes de prueba. El modelo AMMI explicó alrededor del 96 % de la variación debida a la IGA, observándose que sólo los dos primeros ejes concentraron cerca del 85 % de dicha variación. Las variedades locales Chullpi-Q, Carhuay-P, Astilla Blanca-Cusqueado, Astilla Blanca-DH, Cusqueado-P y Astilla Blanca-Astilla Amarilla mostraron el mejor potencial productivo, pero sólo las tres primeras fueron estables a través de los ambientes de evaluación

A High Accurate Approximation for a Galactic Newtonian Nonlinear Model Validated by Employing Observational Data

This article proposes Perturbation Method (PM) to solve nonlinear problems. As case study PM is employed to provide a detailed study of a nonlinear galactic model. Our approach is rather elementary and seeks to explain as much detail as possible the material of this work.In particular our solution gives rise qualitatively, to the known flat rotation curves. In fact, we compare the numerical solution and the obtained approximation by employing observational data proving the validity and high accuracy of the model under study

The Southern Wide-field Gamma-ray Observatory reach for Primordial Black Hole evaporation

The Southern Wide-field Gamma-ray Observatory (SWGO) is a proposed ground-based gamma-ray detector that will be located in the Southern Hemisphere and is currently in its design phase. In this contribution, we will outline the prospects for Galactic science with this Observatory. Particular focus will be given to the detectability of extended sources, such as gamma-ray halos around pulsars; optimisation of the angular resolution to mitigate source confusion between known TeV sources; and studies of the energy resolution and sensitivity required to study the spectral features of PeVatrons at the highest energies. Such a facility will ideally complement contemporaneous observatories in studies of high energy astrophysical processes in our Galaxy

Simulating the performance of the Southern Wide-view Gamma-ray Observatory

The Southern Wide-view Gamma-ray Observatory (SWGO) will be a next-generation gamma-ray observatory using a large array of particle detectors at a high elevation site in South America. This project is currently in a three years R&D phase in which the design will be optimised for cost and performance. Therefore it is crucial to efficiently evaluate the impact of different design options on the scientific objectives of the observatory. In this contribution, we will introduce the strategy and the simulation framework in which this evaluation takes place

Study of water Cherenkov detector designs for the SWGO experiment

The Southern Wide-field Gamma-ray Observatory (SWGO) is a next-generation ground-based gamma-ray detector under development to reach a full sky coverage together with the current HAWC and LHAASO experiments in the northern hemisphere. It will complement the observation of transient and variable multi-wavelength and multi-messenger phenomena, offering moreover the possibility to access the Galactic Centre. One of the possible SWGO configurations consists of an array of water Cherenkov tanks, with a high fill-factor inner array and a low-density outer array, covering an overall area of one order of magnitude larger than HAWC. To reach a high detection efficiency and discrimination capability between gamma-ray and hadronic air showers, various tank designs were studied. Double-layer tanks with several sizes, shapes and number of photomultiplier tubes have been considered. Single-particle simulations have been performed to study the tank response, using muons, electrons, and gamma-rays with energies typical of extensive air showers particles, entering the tanks with zenith angles from 0 to 60 degrees. The tank response was evaluated considering the particle detection efficiency, the number of photoelectrons produced by the photomultiplier tubes, and the time resolution of the measurement of the first photon. The study allowed to compare the performance of tanks with circular and square base, to understand which design optimizes the performance of the array. The method used in the study and the results will be discussed in this paper

Galactic Science with the Southern Wide-field Gamma-ray Observatory

The Southern Wide-field Gamma-ray Observatory (SWGO) is a proposed ground-based gamma-ray detector that will be located in the Southern Hemisphere and is currently in its design phase. In this contribution, we will outline the prospects for Galactic science with this Observatory. Particular focus will be given to the detectability of extended sources, such as gamma-ray halos around pulsars; optimisation of the angular resolution to mitigate source confusion between known TeV sources; and studies of the energy resolution and sensitivity required to study the spectral features of PeVatrons at the highest energies. Such a facility will ideally complement contemporaneous observatories in studies of high energy astrophysical processes in our Galaxy

Monitoring Gamma-Ray Burst VHE emission with the Southern Wide-field-of-view Gamma-ray Observatory

It has been established that Gamma-Ray Bursts (GRB) can produce Very High Energy radiation (E > 100 GeV), opening a new window on the investigation of particle acceleration and radiation properties in the most energetic domain. We expect that next-generation instruments, such as the Cherenkov Telescope Array (CTA), will mark a huge improvement in their observation. However, constraints on the target visibility and the limited duty cycle of Imaging Atmospheric Cherenkov Telescopes (IACT) reduce their ability to react promptly to transient events and to characterise their general properties. Here we show that an instrument based on the Extensive Air Shower (EAS) array concept, proposed by the Southern Wide Field-of-view Gamma-ray Observatory (SWGO) Collaboration, has promising possibilities to detect and track VHE emission from GRBs. Observations made by the Fermi Large Area Telescope (Fermi-LAT) identified some events with a distinct spectral component, extending above 1 GeV or even 10 GeV, which can represent a substantial fraction of the emitted energy and also arise in early stages of the process. Using models based on these properties, we estimate the possibilities that a wide field of view and large effective area ground-based monitoring facility has to probe VHE emission from GRBs. We show that the ability to monitor VHE transients with a nearly continuous scanning of the sky grants an opportunity to access simultaneous electromagnetic counterparts to Multi-Messenger triggers up to cosmological scales, in a way that is not available to IACTs