Elétrons fortemente correlacionados na vizinhança de uma transição de fase quântica

The aim of this work is to derive theWard Identity for the low energy effective theory of a fermionic system in the presence of a hyperbolic Fermi surface coupled with a U(1) gauge field in 2+1 dimensions. These identities are important because they establish requirements for the theory to be gauge invariant. We will see that the identity associated Ward Identity (WI) of the model is not preserved at 1-loop order. This feature signalizes the presence of a quantum anomaly. In other words, a classical symmetry is broken dynamically by quantum fluctuations. Furthermore, we are considering that the system is close to a Quantum Phase Transitions and in vicinity of a Quantum Critical Point the fermionic excitations near the Fermi surface, decay through a Landau damping mechanism. All this ingredients need to be take explicitly to account and this leads us to calculate the vertex corrections as well as self energies effects, which in this way lead to one particle propagators which have a non-trivial frequency dependence

Efeitos não-gaussianos em astrofísica e cosmologia

The recent astronomical observations indicate that the universe has null spatial curvature, is accelerating and its matter-energy content is composed by circa 30% of matter (baryons + dark matter) and 70% of dark energy, a relativistic component with negative pressure. However, in order to built more realistic models it is necessary to consider the evolution of small density perturbations for explaining the richness of observed structures in the scale of galaxies and clusters of galaxies. The structure formation process was pioneering described by Press and Schechter (PS) in 1974, by means of the galaxy cluster mass function. The PS formalism establishes a Gaussian distribution for the primordial density perturbation field. Besides a serious normalization problem, such an approach does not explain the recent cluster X-ray data, and it is also in disagreement with the most up-to-date computational simulations. In this thesis, we discuss several applications of the nonextensive q-statistics (non-Gaussian), proposed in 1988 by C. Tsallis, with special emphasis in the cosmological process of the large structure formation. Initially, we investigate the statistics of the primordial fluctuation field of the density contrast, since the most recent data from the Wilkinson Microwave Anisotropy Probe (WMAP) indicates a deviation from gaussianity. We assume that such deviations may be described by the nonextensive statistics, because it reduces to the Gaussian distribution in the limit of the free parameter q = 1, thereby allowing a direct comparison with the standard theory. We study its application for a galaxy cluster catalog based on the ROSAT All-Sky Survey (hereafter HIFLUGCS). We conclude that the standard Gaussian model applied to HIFLUGCS does not agree with the most recent data independently obtained by WMAP. Using the nonextensive statistics, we obtain values much more aligned with WMAP results. We also demonstrate that the Burr distribution corrects the normalization problem. The cluster mass function formalism was also investigated in the presence of the dark energy. In this case, constraints over several cosmic parameters was also obtained. The nonextensive statistics was implemented yet in 2 distinct problems: (i) the plasma probe and (ii) in the Bremsstrahlung radiation description (the primary radiation from X-ray clusters); a problem of considerable interest in astrophysics. In another line of development, by using supernova data and the gas mass fraction from galaxy clusters, we discuss a redshift variation of the equation of state parameter, by considering two distinct expansions. An interesting aspect of this work is that the results do not need a prior in the mass parameter, as usually occurs in analyzes involving only supernovae data.Finally, we obtain a new estimate of the Hubble parameter, through a joint analysis involving the Sunyaev-Zeldovich effect (SZE), the X-ray data from galaxy clusters and the baryon acoustic oscillations. We show that the degeneracy of the observational data with respect to the mass parameter is broken when the signature of the baryon acoustic oscillations as given by the Sloan Digital Sky Survey (SDSS) catalog is considered. Our analysis, based on the SZE/X-ray data for a sample of 25 galaxy clusters with triaxial morphology, yields a Hubble parameter in good agreement with the independent studies, provided by the Hubble Space Telescope project and the recent estimates of the WMAP

Ocidentalização, territórios e populações indígenas no sertão da Capitania do Rio Grande

The objective of this work is to understand some of the modifications caused for the phenomenon of the westernization in the hinterland of the Capitania do Rio Grande e in the life of the indians populations that inhabited there during the Colonial Period. We break of the quarrel of Serge Gruzinski concerning the westernization, understood while immersed phenomenon in the context of the expansion of the commercial capitalism and that, for the imposition of the culture occidental person to the alteridades of the New World, emprende the conquest of its territories, bodies and souls. The space clipping has covered the hinterland of the Capitania do Rio Grande, specifically the colonial territory of the Freguesia da Gloriosa Senhora Santa Ana do Seridó. The chosen chronological limit for the research corresponds to the Colonial Period and part of the Imperial one. However, the emphasis falls again on the period that it initiates in 1670, year of the oldest concession of would sesmaria known until the moment in the hinterland of the Rio Grande, extending itself until the decade of 1840. Sources of written by hand nature, cartographic printed and compose the used document roll: official correspondence and legislation, petitions of would sesmaria, inventories post-mortem, justifications of debt, registers of parish, maps, action civil court jurisdiction, notes of notary's office, land landmarks. We take the method, analyzed for Carlo Ginzburg, to cross these sources between itself and to detect its implied particularitities and ideas in the space between lineses, but, attributing it status to they of a colonial speech, fruit of the bureaucracy of where it was originated and of the social place of who produced it. We look for to demonstrate, throughout the work, that the phenomenon of the westernization desestruturou the aboriginal societies and its habitat, constructing, over its rubbles, a colonial territory that found in the cartography of the Freguesia de Santa Ana an efficient instrument of control of the space and the population. On the other hand, if the imposition of the culture occidental person exterminou great part of the native population that inhabited the hinterland of the Rio Grande, the remainders of these indians and the mestizos of descending them had survived in diverse ways in the freguesia: in the condition of captives of war or in regimen of servile work, as living or assistants in the farms, populations and village; rambling without route in the fields and the population spots; as mediating agents between the world occidental person and the native, exerting military or civil positions and still appealing to Justice in search of its rights of inheritance. Experiences of slavery, servitude, errância and mediation, but, also of resistance, adaptation, mestization in the Freguesia de Santa Ana

O padre, o filósofo e o profeta : a América de Simão de Vasconcelos

To build an Portuguese America, after discovering at the beginning of XVI century, the Europeans used the physic, politic colonization and also a space ideological domain using write texts, chronicles, and started making a conceive America that was more European than American. One of those chronicles was the Society of Jesus Chronicle written by father Simão de Vasconcelos, a Jesuit. So our object is recognizing in this chronicle the ways that this father had imagined the America. We are looking to answer how the Jesuit use some references to Classic Antiquity (meanly Aristotle and Samuel) because how this action until happen in the Renascence (XVII century) the intellectual production certainly involve renascent topoi. To get this we used some authors that study Intellectual/ Cultural History like Burckhardt e Ginzburg and some authors from Speech Analyses like Certeau and Foucault, to, in the end, can understand how Simão de Vasconcelos created his Brazil

A quantum chemical study on the formation of phosphorus mononitride

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New approaches in W gravities

We devote effort to studying some nonlinear actions, characteristic of W theories, in the framework of the soldering formalism. We disclose interesting new results concerning the embedding of the original chiral W particles in different metrical spaces in the final soldered action; i.e., the metric is modified by the soldering interference process. The results are presented in a weak field approximation for the W-N case when Ngreater than or equal to3 and also in an exact way for W-2. We promote a generalization of the interference phenomenon to W-N theories of different chiralities and show that the geometrical features introduced can yield a new understanding of the interference formalism in quantum field theories.

Espalhamento e estados ligados em potenciais localizados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Extension of PT-symmetric quantum mechanics to the Dirac theory with position-dependent mass

We present a new method to construct the exactly solvable PT-symmetric potentials within the framework of the position-dependent effective mass Dirac equation with the vector potential coupling scheme in 1 + 1 dimensions. In order to illustrate the procedure, we produce three PT-symmetric potentials as examples, which are PT-symmetric harmonic oscillator-like potential, PT-symmetric potential with the form of a linear potential plus an inversely linear potential, and PT-symmetric kink-like potential, respectively. The real relativistic energy levels and corresponding spinor components for the bound states are obtained by using the basic concepts of the supersymmetric quantum mechanics formalism and function analysis method. (C) 2007 Elsevier B.V. All rights reserved.

Effects Due to a Scalar Coupling on the Particle-Antiparticle Production in the Duffin-Kemmer-Petiau Theory

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Spinless bosons embedded in a vector Duffin-Kemmer-Petiau oscillator

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Phase transition and dielectric properties of La-doped Pb(Zr, Ti)O-3 antiferroelectric ceramics

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

Non-Zeeman splitting for a spin-resolved STM with a Kondo adatom in a spin-polarized two-dimensional electron gas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

BSmart: desenvolvimento rigoroso de aplicações Java Card com base no método formal B

Java Card technology allows the development and execution of small applications embedded in smart cards. A Java Card application is composed of an external card client and of an application in the card that implements the services available to the client by means of an Application Programming Interface (API). Usually, these applications manipulate and store important information, such as cash and confidential data of their owners. Thus, it is necessary to adopt rigor on developing a smart card application to improve its quality and trustworthiness. The use of formal methods on the development of these applications is a way to reach these quality requirements. The B method is one of the many formal methods for system specification. The development in B starts with the functional specification of the system, continues with the application of some optional refinements to the specification and, from the last level of refinement, it is possible to generate code for some programming language. The B formalism has a good tool support and its application to Java Card is adequate since the specification and development of APIs is one of the major applications of B. The BSmart method proposed here aims to promote the rigorous development of Java Card applications up to the generation of its code, based on the refinement of its formal specification described in the B notation. This development is supported by the BSmart tool, that is composed of some programs that automate each stage of the method; and by a library of B modules and Java Card classes that model primitive types, essential Java Card API classes and reusable data structures

Uma abordagem para promover o alinhamento entre a estratégia de negócio e a tecnologia de informação

Currently with the increase in complexity in doing business, organizations are seeking information systems that help to quickly respond to new demands in the processes of production of products and services. An information system is no longer just a support tool and has become an integral part of doing business. However, in spite of significant technological evolution in recent years, information systems that support business do not respond efficiently to the constant alterations that occur in many organizations. One of the main problems faced by information systems currently is the lack of strategic alignment between business strategy and information technology. The concept of strategic alignment can be defined as a way between business strategies and objectives and the strategies, objectives and functions of information technology in such as way as to contribute to the increase in competitivity of the organization over time. Strategic alignment together with strategic planning are important management instruments. Approaches for operationalizing this alignment are being developed currently but are still in their initial stages due to the fact that it is a relatively new concept in the literature. Another point that needs to be taken into consideration during the strategic alignment is the question of trackability between the business elements and IT. Trackability (Tracking) is necessary for example when one wishes to know exactly which goal defined in the business strategy was left out or not accepted due to a modification made in the IT strategy. Very few proposals present concrete ways supported by software systems in order to obtain strategic alignement while taking into consideration this trackability. Therefore the objective of this work is to propose the creation of a strategic alignment process supported by a software system which is capable of permitting trackability between the organizational objectives and the business processes based on formalization standards defined through a model oriented approach

Teorias f(R) de gravidade na formulação de Palatini

In this dissertation, after a brief review on the Einstein s General Relativity Theory and its application to the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological models, we present and discuss the alternative theories of gravity dubbed f(R) gravity. These theories come about when one substitute in the Einstein-Hilbert action the Ricci curvature R by some well behaved nonlinear function f(R). They provide an alternative way to explain the current cosmic acceleration with no need of invoking neither a dark energy component, nor the existence of extra spatial dimensions. In dealing with f(R) gravity, two different variational approaches may be followed, namely the metric and the Palatini formalisms, which lead to very different equations of motion. We briefly describe the metric formalism and then concentrate on the Palatini variational approach to the gravity action. We make a systematic and detailed derivation of the field equations for Palatini f(R) gravity, which generalize the Einsteins equations of General Relativity, and obtain also the generalized Friedmann equations, which can be used for cosmological tests. As an example, using recent compilations of type Ia Supernovae observations, we show how the f(R) = R − fi/Rn class of gravity theories explain the recent observed acceleration of the universe by placing reasonable constraints on the free parameters fi and n. We also examine the question as to whether Palatini f(R) gravity theories permit space-times in which causality, a fundamental issue in any physical theory [22], is violated. As is well known, in General Relativity there are solutions to the viii field equations that have causal anomalies in the form of closed time-like curves, the renowned Gödel model being the best known example of such a solution. Here we show that every perfect-fluid Gödel-type solution of Palatini f(R) gravity with density and pressure p that satisfy the weak energy condition + p 0 is necessarily isometric to the Gödel geometry, demonstrating, therefore, that these theories present causal anomalies in the form of closed time-like curves. This result extends a theorem on Gödel-type models to the framework of Palatini f(R) gravity theory. We derive an expression for a critical radius rc (beyond which causality is violated) for an arbitrary Palatini f(R) theory. The expression makes apparent that the violation of causality depends on the form of f(R) and on the matter content components. We concretely examine the Gödel-type perfect-fluid solutions in the f(R) = R−fi/Rn class of Palatini gravity theories, and show that for positive matter density and for fi and n in the range permitted by the observations, these theories do not admit the Gödel geometry as a perfect-fluid solution of its field equations. In this sense, f(R) gravity theory remedies the causal pathology in the form of closed timelike curves which is allowed in General Relativity. We also examine the violation of causality of Gödel-type by considering a single scalar field as the matter content. For this source, we show that Palatini f(R) gravity gives rise to a unique Gödeltype solution with no violation of causality. Finally, we show that by combining a perfect fluid plus a scalar field as sources of Gödel-type geometries, we obtain both solutions in the form of closed time-like curves, as well as solutions with no violation of causality