Geração de massa em Teorias de Gauge

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

As paisagens fantásticas numa cidade amazônica sob o olhar dos taxistas

Este artigo tem como objetivo analisar as impressões e as interpretações de antigos taxistas a respeito das mudanças ocorridas na cidade de Belém no decorrer do século XX. Nesse contexto, os motoristas autônomos de Belém figuram como portadores de um conhecimento sobre a cidade baseado na prática do deslocamento, revelando uma memória coletiva ligada aos processos de urbanização e transformação do viver na capital paraense. Emerge, então, um imaginário construído a respeito da cidade de Belém no interior de uma categoria profissional específica, bem como representações, aspirações, devaneios e queixas comuns sobre o viver na cidade. Assim, os pontos de vista desses profissionais sobre Belém aparecem expressos em narrativas fantásticas em que os taxistas encontram visagens e assombrações durante sua jornada de trabalho.

Teorias de Spin-1: decomposição em helicidades, redução dimensional e imersão de calibre

We have studied the physical content of the following models: Maxwell, Proca, Self-Dual and Maxwell-Chern-Simons. One method we have used is the decomposition in the so called helicity variables, which can be done in the Lagrangian formalism. It leads to the correct counting of degrees of freedom without choosing a gauge condition. The method separates the propagating modes from the non-propagating ones. The Hamiltonian of the MCS and the AD is calculated. The second method used here is the analysis of the sign of the imaginary part of the residues of the two-point amplitude of the theory, showing that the models analyzed are free of ghosts. We also carry the dimensional reduction of the Maxwell-Chern-Simons and Self-Dual models from D = 2+1 to D = 1 + 1 dimensions. Next, we show that the dimensional reduction of those equivalent models also leads to equivalent models in D=1+1. Even more interesting is the fact, demonstrated here, that those reduced models can also be connected via gauge embedding. So the gauge embedding of the Self-Dual model into the Maxwell-Chern-Simons theory is preserved by the dimensional reduction

Retratos da Espanha em Os fantasmas de Goya

1792, Madri. After years of inactivity, the Spanish Inquisition is born again with the mission of containing the laic winds that blow from the revolutionary France. Inês Bilbatúa, a rich merchant’s daugther, is victim of the inquisitorial machinery which tortures and violates her, through one of their abetters, the Dominican monk Lorenzo. Before being arrested, the young lady had served as model for the painter Francisco of Goya, who had also portrayed the monk Lorenzo. The Aragonese painter’s figure serves as narrative conductor of a history that narrates the young Inês’ via crucis and, at the same time, it recreates the historical scenery of the Napoleonic invasion (1808), through a basic element, the painting. Our work intends to analyze the relationships among movie, painting and history present in “Goya’s ghosts” (2006), of the Czech director Milos Forman (1932) - whose script was adapted to a homonymous book in 2007 -, a movie that is based on the artistic production of Francisco of Goya y Lucientes (1746 -1828), official painter of Carlos’ IV (1788 -1808) court and the most lucid columnist of his time, that knew how to capture in his works the religious fanaticism, the populist fervour, the governor’s hypocrisy and the horror and the violence of the war.

Twistor origin of the superstring

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dual descriptions of massive spin-3 particles in D=2+1 via Noether gauge embedment

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Massive spin-2 particles via embedment of the Fierz-Pauli equations of motion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Pure spinor superstring partition function

Pós-graduação em Física - IFT

Supersymmetric Dark Matter : aspects of sfermion coannihilations

There is very strong evidence that ordinary matter in the Universe is outweighed by almost ten times as much so-called dark matter. Dark matter does neither emit nor absorb light and we do not know what it is. One of the theoretically favoured candidates is a so-called neutralino from the supersymmetric extension of the Standard Model of particle physics. A theoretical calculation of the expected cosmic neutralino density must include the so-called coannihilations. Coannihilations are particle processes in the early Universe with any two supersymmetric particles in the initial state and any two Standard Model particles in the final state. In this thesis we discuss the importance of these processes for the calculation of the relic density. We will go through some details in the calculation of coannihilations with one or two so-called sfermions in the initial state. This includes a discussion of Feynman diagrams with clashing arrows, a calculation of colour factors and a discussion of ghosts in non-Abelian field theory. Supersymmetric models contain a large number of free parameters on which the masses and couplings depend. The requirement, that the predicted density of cosmic neutralinos must agree with the density observed for the unknown dark matter, will constrain the parameters. Other constraints come from experiments which are not related to cosmology. For instance, the supersymmetric loop contribution to the rare b -> sγ decay should agree with the measured branching fraction. The principles of the calculation of the rare decay are discussed in this thesis. Also on-going and planned searches for cosmic neutralinos can constrain the parameters. In one of the accompanying papers in the thesis we compare the detection prospects for several current and future searches for neutralino dark matter.

Quantum field theory of (p,0)-forms on kaehler manifolds

In questa tesi abbiamo studiato la quantizzazione di una teoria di gauge di forme differenziali su spazi complessi dotati di una metrica di Kaehler. La particolarità di queste teorie risiede nel fatto che esse presentano invarianze di gauge riducibili, in altre parole non indipendenti tra loro. L'invarianza sotto trasformazioni di gauge rappresenta uno dei pilastri della moderna comprensione del mondo fisico. La caratteristica principale di tali teorie è che non tutte le variabili sono effettivamente presenti nella dinamica e alcune risultano essere ausiliarie. Il motivo per cui si preferisce adottare questo punto di vista è spesso il fatto che tali teorie risultano essere manifestamente covarianti sotto importanti gruppi di simmetria come il gruppo di Lorentz. Uno dei metodi più usati nella quantizzazione delle teorie di campo con simmetrie di gauge, richiede l'introduzione di campi non fisici detti ghosts e di una simmetria globale e fermionica che sostituisce l'iniziale invarianza locale di gauge, la simmetria BRST. Nella presente tesi abbiamo scelto di utilizzare uno dei più moderni formalismi per il trattamento delle teorie di gauge: il formalismo BRST Lagrangiano di Batalin-Vilkovisky. Questo metodo prevede l'introduzione di ghosts per ogni grado di riducibilità delle trasformazioni di gauge e di opportuni “antifields" associati a ogni campo precedentemente introdotto. Questo formalismo ci ha permesso di arrivare direttamente a una completa formulazione in termini di path integral della teoria quantistica delle (p,0)-forme. In particolare esso permette di dedurre correttamente la struttura dei ghost della teoria e la simmetria BRST associata. Per ottenere questa struttura è richiesta necessariamente una procedura di gauge fixing per eliminare completamente l'invarianza sotto trasformazioni di gauge. Tale procedura prevede l'eliminazione degli antifields in favore dei campi originali e dei ghosts e permette di implementare, direttamente nel path integral condizioni di gauge fixing covarianti necessari per definire correttamente i propagatori della teoria. Nell'ultima parte abbiamo presentato un’espansione dell’azione efficace (euclidea) che permette di studiare le divergenze della teoria. In particolare abbiamo calcolato i primi coefficienti di tale espansione (coefficienti di Seeley-DeWitt) tramite la tecnica dell'heat kernel. Questo calcolo ha tenuto conto dell'eventuale accoppiamento a una metrica di background cosi come di un possibile ulteriore accoppiamento alla traccia della connessione associata alla metrica.

Form as Three Questions

Emmanuel Levinas once stated that his “project” was “the deformalization of time.” Jacques Derrida, too, laid out a framework of thinking about time that dismissed the relevance of the past and the future and even belittled the significance of/or ourability to know anything about the “present.” Both of these thinkers discussed such notions of time in the context of complex theories of representation—or of the “relationship” between signifier and signified. This thesis considers the connection between theories of time and conceptions of the “relationship” between signifier andsignified to ask how Hamlet’s role as the agent of the plot in Hamlet relates to his own consideration of his “relationship” to the ghost as a potentially empty signifier.

Experimental infection of the pig with Mycobacterium ulcerans: a novel model for studying the pathogenesis of Buruli ulcer disease.

BACKGROUND Buruli ulcer (BU) is a slowly progressing, necrotising disease of the skin caused by infection with Mycobacterium ulcerans. Non-ulcerative manifestations are nodules, plaques and oedema, which may progress to ulceration of large parts of the skin. Histopathologically, BU is characterized by coagulative necrosis, fat cell ghosts, epidermal hyperplasia, clusters of extracellular acid fast bacilli (AFB) in the subcutaneous tissue and lack of major inflammatory infiltration. The mode of transmission of BU is not clear and there is only limited information on the early pathogenesis of the disease available. METHODOLOGY/PRINCIPAL FINDINGS For evaluating the potential of the pig as experimental infection model for BU, we infected pigs subcutaneously with different doses of M. ulcerans. The infected skin sites were excised 2.5 or 6.5 weeks after infection and processed for histopathological analysis. With doses of 2 × 10(7) and 2 × 10(6) colony forming units (CFU) we observed the development of nodular lesions that subsequently progressed to ulcerative or plaque-like lesions. At lower inoculation doses signs of infection found after 2.5 weeks had spontaneously resolved at 6.5 weeks. The observed macroscopic and histopathological changes closely resembled those found in M. ulcerans disease in humans. CONCLUSION/SIGNIFICANCE Our results demonstrate that the pig can be infected with M. ulcerans. Productive infection leads to the development of lesions that closely resemble human BU lesions. The pig infection model therefore has great potential for studying the early pathogenesis of BU and for the development of new therapeutic and prophylactic interventions.

Soil properties of western Wright Valley, Antarctica

Western Wright Valley, from Wright Upper Glacier to the western end of the Dais, can be divided into three broad geomorphic regions: the elevated Labyrinth, the narrow Dais which is connected to the Labyrinth, and the North and South forks which are bifurcated by the Dais. Soil associations of Typic Haplorthels/Haploturbels with ice-cemented permafrost at < 70 cm are most common in each of these geomorphic regions. Amongst the Haplo Great Groups are patches of Salic and Typic Anhyorthels with ice-cemented permafrost at > 70 cm. They are developed in situ in strongly weathered drift with very low surface boulder frequency and occur on the upper erosion surface of the Labyrinth and on the Dais. Typic Anhyorthels also occur at lower elevation on sinuous and patchy Wright Upper III drift within the forks. Salic Aquorthels exist only in the South Fork marginal to Don Juan Pond, whereas Salic Haplorthels occur in low areas of both South and North forks where any water table is > 50 cm. Most soils within the study area have an alkaline pH dominated by Na+ and Cl- ions. The low salt accumulation within Haplorthels/Haploturbels may be due to limited depth of soil development and possibly leaching.

Por qué escribí La pasión de los nómades (1994) : un libro y muchos viajes

Se trata de una reflexión solicitada a la autora sobre su novela La pasión de los nómades (1994), que propone el retorno del Lucio V. Mansilla de Una excursión a los indios ranqueles (1879) a la Argentina de la década del '90 en el siglo XX. Novela de cruces (de géneros sexuales y ontológicos, de géneros literarios, de lenguas y culturas, de textos y discursos, del mito y la parodia ), Supone también un cruce de viajeros y merodeadores incansables: sobrenaturales peregrinos del mundo celta (Merlín y Rosaura), vulgares y menesterosos inmigrantes, fantasmas de cristianos y de ranqueles. La novela, cuya génesis se cuenta en estas páginas supuso también un viaje geográfico real sobre el que la autora se detiene especialmente.

Cáscaras vacías, un agujero en el orden del ser : Espectralidad y política en la literatura de Juan José Saer

La violencia como condición de posibilidad de la literatura es una idea esbozada por Saer. Su planteamiento nos conduce a reflexionar sobre cómo se configura la relación entre la dimensión política y social y el mundo específico de la escritura. Si se piensa su propia literatura a partir de lo que ha denominado "moral del fracaso" en el Quijote, podríamos decir, retomando a Julio Premat, que sus personajes habitan en una situación de duelo en donde el universo moral, las filiaciones familiares y políticas se encuentran profundamente resquebrajadas. Hay un sentimiento de pérdida y esto conlleva el acecho incesante de los fantasmas y las formas diversas de expurgarlos en una puja dentro del orden de la representación simbólica