BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysis

We study a family of circular BPS Wilson loops in N=6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) counterpart of the DGRT latitudes defined in N=4 SYM. We perform a complete two-loop analysis of their vacuum expectation value, discuss the framing dependence and propose a general relation with cohomologically equivalent bosonic operators. We make an all-loop proposal for computing the Bremsstrahlung function associated to the 1/2-BPS cusp in terms of these generalized Wilson loops. When applied to our two-loop result it reproduces the known expression. Finally, we comment on the generalization of this proposal to the bosonic 1/6-BPS case.Comment: 46 pages, 6 figures; references adde

A matrix model for the latitude Wilson loop in ABJM theory

In ABJ(M) theory, we propose a matrix model for the exact evaluation of BPS Wilson loops on a latitude circular contour, so providing a new weak-strong interpolation tool. Intriguingly, the matrix model turns out to be a particular case of that computing torus knot invariants in $U(N_1|N_2)$ Chern-Simons theory. At weak coupling we check our proposal against a three-loop computation, performed for generic framing, winding number and representation. The matrix model is amenable of a Fermi gas formulation, which we use to systematically compute the strong coupling and genus expansions. For the fermionic Wilson loop the leading planar behavior agrees with a previous string theory prediction. For the bosonic operator our result provides a clue for finding the corresponding string dual configuration. Our matrix model is consistent with recent proposals for computing Bremsstrahlung functions exactly in terms of latitude Wilson loops. As a by-product, we extend the conjecture for the exact $B^{\theta}_{1/6}$ Bremsstrahlung function to generic representations and test it with a four-loop perturbative computation. Finally, we propose an exact prediction for $B_{1/2}$ at unequal gauge group ranks.Comment: 73 pages; v2: several improvements, JHEP published versio

The quantum 1/2 BPS Wilson loop in N=4{\cal N}=4 Chern-Simons-matter theories

In three dimensional ${\cal N}=4$ Chern-Simons-matter theories two independent fermionic Wilson loop operators can be defined, which preserve half of the supersymmetry charges and are cohomologically equivalent at classical level. We compute their three-loop expectation value in a convenient color sector and prove that the degeneracy is uplifted by quantum corrections. We expand the matrix model prediction in the same regime and by comparison we conclude that the quantum 1/2 BPS Wilson loop is the average of the two operators. We provide an all-loop argument to support this claim at any order. As a by-product, we identify the localization result at three loops as a correction to the framing factor induced by matter interactions. Finally, we comment on the quantum properties of the non-1/2 BPS Wilson loop operator defined as the difference of the two fermionic ones.Comment: 22 pages + appendixes, 4 figures, 1 Tabl

Towards the exact Bremsstrahlung function of ABJM theory

We present the three-loop calculation of the Bremsstrahlung function associated to the 1/2-BPS cusp in ABJM theory, including color subleading corrections. Using the BPS condition we reduce the computation to that of a cusp with vanishing angle. We work within the framework of heavy quark effective theory (HQET) that further simplifies the analytic evaluation of the relevant cusp anomalous dimension in the near-BPS limit. The result passes nontrivial tests, such as exponentiation, and is in agreement with the conjecture made in [1] for the exact expression of the Bremsstrahlung function, based on the relation with fermionic latitude Wilson loops.Comment: 46 pages, 15 figure

Help! I need somebody! Multidisciplinary support forworkers in the economic crisis

La actual crisis económica está causando dificultades a una gran cantidad de trabajadores en diferentes campos, y ahora, muchos de ellos, se encuentran necesitando ayuda. La pregunta es cómo apoyarles de manera eficaz, sobre todo teniendo en cuenta la amplia gama de condiciones, problemas, enfermedades, y temores que experimentan en relación a la situación económica. Desde esta perspectiva, un factor crítico de éxito se puede identificar en la naturaleza multidisciplinar de la intervención. De hecho, la ayuda no puede ser sólo psicológica: también existe la necesidad de apoyo jurídico, económico, social y médico. El psicólogo, dentro de este marco, desempeña un papel fundamental: no sólo el de prestar ayuda psicológica, sino también el de la coordinación de los otros profesionales con el fin de producir un servicio integrado que sea aceptable, comprensible y útil para los trabajadores en busca de apoyo. Este artículo examina la experiencia del Centro de asistencia multidisciplinar creado en el área de Padova, Italia, para la asistencia a los trabajadores que experimentan dificultades relacionadas con la crisis. Este centro fue creado en 2010 después de una serie de suicidios que podrían estar relacionados con el trabajo, y contribuyó a ayudar a más de 150 trabajadores. Se procede a examinar y discutir sus metodologías, procedimientos y resultados.The current economic crisis is causing difficulties to a vast amount of workers in different fields, and many of them now find themselves in need of help. The question is how to effectively support them, especially considering the wide range of conditions, problems, diseases, and fears that they experience in relation to the contingent economic situation. In this perspective, one critical success factor can be identified in the multidisciplinary natureof the intervention. In fact the help cannot be just psychological: there is also the need of legal, economic, social and medical support. The psychologist, in this perspective, has a pivotal role: not only the one of giving psychological aid, but also the one of coordinating the other professionals in order to produce an integrated service that is acceptable, understandable and useful for the workers seeking support. This paper examines the experience of the multidisciplinary help center created in the area of Padova, Italy, for the assistance to workers experiencing difficulties related to the crisis. This center was established in 2010 after a series of suicides that could be related to work, and contributed to help more than 150 workers. Its methodologies, procedures and results are examined and discussed.peerReviewe

Dati preliminari di abbondanza e distribuzione di Salmo fibreni Zerunian & Gandolfi 1990 nel bacino di Posta Fibreno (Italia Centrale): primo utilizzo del visual census

Preliminary abundance and distribution data of Salmo fibreni Zerunian & Gandolfi 1990 in the Posta Fibreno basin (Central Italy): first use of visual census - Lake Posta Fibreno and Stream Dova harbour Salmo fibreni Zerunian & Gandolfi 1990, an endemic taxon still quite unknown in its phenology and ecology. We report here a first attempt to quantitatively estimate the abundance of the lacustrine population of S. fibreni by means of the visual census method, generally considered as a non-intrusive technique and capable of providing ecological information otherwise not achievable. A total of 19 observations (snorkelling and scuba diving) during 1 year (September 2006-July 2007) in the lake zones presently frequented by S. fibreni were performed along transects of 100-130 m length by two observers. Densities of S. fibreni resulted to be negatively affected by light (1 single diurnal contact) and very low everywhere in the lake (mean 2 ind per 100 m, max 9 ind per 100 m), especially if compared to Rio Dova densities as derived from electrofishing. The distribution of S. fibreni within the basin seems to be strictly dependent on substrate composition, springs proximity, presence of flourishing aquatic vegetation. Immediate measures of conservation and support appear to be necessary, as the species individual numbers clearly point out a high risk of extinction

Introduction to Morphodynamics of Sedimentary Patterns

Morphodynamics is a new discipline that investigates the formation and development of sedimentary patterns, i.e. the shapes of the cohesionless or cohesive boundaries of water bodies, evolving in response to the action of flowing water. Sedimentary patterns occur in fluvial, transitional, coastal and submarine environments. Their fascinating forms (e.g. dunes, meanders, alluvial fans, deltas, lagoons, coastal bars, tidal ridges, submarine fans) have attracted the attention of scientists. They also play a major role in fluvial, coastal and offshore engineering. The present monograph is the first of a series planned by an Editorial Committee comprising the four Authors. It provides a phenomenological introduction to the variety of patterns that will be investigated in the future Monographs. It also introduces to the mathematical theory of Morphodynamics, clarifying its nature of free boundary problem for the interface between a flowing water-sediment mixture and an erodible boundary