Spectral functions in a magnetic field as a probe of spin-charge separation in a Luttinger liquid

We show that the single-particle spectral functions in a magnetic field can be used to probe spin-charge separation of a Luttinger liquid. Away from the Fermi momentum, the magnetic field splits both the spinon peak and holon peak; here the spin-charge separation nature is reflected in the different magnitude of the two splittings. At the Fermi momentum, the magnetic field splits the zero-field peak into {\it four} peaks. The feasibility of experimentally studying this effect is discussed.Comment: 4 pages, 3 figures; published versio

BFV Quantization of Relativistic Spinning Particles with a Single Bosonic Constraint

Using the BFV approach we quantize a pseudoclassical model of the spin one half relativistic particle that contains a single bosonic constraint, contrary to the usual locally supersymmetric models that display first and second class constraints.Comment: 5 p., Latex, IF-UFRJ-94-1

An operator approach to BRST invariant transition amplitudes

The transition amplitudes for the free spinless and spinning relativistic particles are obtained by applying an operator method developed long ago by Dirac and Schwinger to the BFV form of the BRST theory for constrained systems.Comment: 10 pages, Latex, IF-UFRJ-9

On gauge invariance and the path integral

Using a gauge covariant operator technique we deduce the path integral for a charged particle in a stationary magnetic field, verifying the "midpoint rule" for the discrete form of the interaction term with the vector potential.Comment: 4 pages, Latex, IF-UFRJ-9

Representações sociais de inovação pedagógica por professores da educação básica

Legislation and public policies for Education, rather than opening the space for innovation in pedagogical practices, places it as a primary factor for the improvement in Education in Brazil. However, one cannot speak of innovation in this field, without looking at the teacher, who is fundamental in this field. Having the teacher as a fundamental agent in Education, it is necessary to be attentive to their professional practice. The literature points to a gap between what is said about innovation and what is actually done by teachers. In general, there is a desire to innovate, but this does not appear in teaching practices. Thus, discourses sustain ideas that are incompatible with educational contexts, generating an abyss between what is sought and what is realized. The objective of this study was to investigate with the teachers of Basic Education, the social representations regarding Pedagogical Innovation. The research was carried out taking the procedural approach of Theory of Social Representations, as a theoretical-methodological reference. Ten Basic Education teachers contributed to the research. Semi-structured interviews and non-participant observation were used, interviews were analyzed using the Argumentative Strategy Model (MEA). It was verified that their representations are aimed at: change, improve, and differentiate and novelty and anchor themselves in: new technologies and constructivism, elements from their initial formation. It was concluded that the participating subjects see Pedagogical Innovation as something external to themselves and sometimes distant. They relate the term to technology, do not perceive themselves as subjects that promote innovation and present several obstacles to an innovative pedagogical practice.La legislación y las políticas públicas para la educación, mucho más que abrir el espacio  para la innovación en prácticas pedagógicas, la colocacomo un factor primordial para la mejora  en la educación en el Brasil. Sin embargo, no se puede hablar en innovación en ese campo, sin mirar al profesor, que es fundamental en ese campo. Teniendo el docentecomo agente fundamental en la educación, cabe estar atento a su práctica profesional. La literatura apunta una brecha entre lo que se habla de innovación y lo que de hecholo hacen los profesores. En general hay un deseo de innovar, pero eso no aparece en las prácticas docentes. Así, los discursos sostienen ideas que son incompatibles con los contextos educacionales, generando un abismo entre lo que se anhela y lo que se realiza. El objetivo de ese estudio fue investigar junto a los profesores de la Educación Básica, las representaciones sociales acerca de Innovación pedagógica. La pesquisa fue realizada teniendo el abordaje procesal de la Teoría de las Representaciones Sociales, como referencial teórico-metodológico. Diez profesores de la Educación Básica contribuyeron para la investigación. Se utilizaron entrevistas semiestructuradas y observación no participante, las entrevistas fueron analizadas con la utilización del Modelo de la Estrategia Argumentativa (MEA). Se verificó que sus representaciones se objetivan en: cambiar, mejorar, diferenciar y novedad y se anclan en: nuevas tecnologías y constructivismo, elementos oriundos de su formación inicial. Se concluyó que los sujetos participantes ven la Innovación Pedagógica como algo externo a si y, a veces, distante. Relacionan el termo a la tecnología, no se percibe como sujetos promotores de la innovación y representan varios obstáculos a una práctica pedagógica innovadora.  A legislação e as políticas públicas para a Educação, bem mais que abrir o espaço para a inovação em práticas pedagógicas, a coloca como um fator primordial para a melhoria na Educação no Brasil. Entretanto, não se pode falar em inovação nesse campo, sem olhar para o professor, que é fundamental nesse campo. Tendo o docente como agente fundamental na Educação, cabe estar atento à sua prática profissional. A literatura aponta uma lacuna entre o que se fala sobre inovação e o que de fato é feito pelos professores. De modo geral, há um desejo de inovar, mas isso não aparece nas práticas docentes. Assim, os discursos sustentam ideias que são incompatíveis com os contextos educacionais, gerando um abismo entre o que se almeja e o que se realiza. O objetivo desse estudo foi investigar junto aos professores da Educação Básica, as representações sociais a respeito de Inovação Pedagógica. A pesquisa foi realizada tendo a abordagem processual da Teoria das Representações Sociais, como referencial teórico-metodológico. Dez professores da Educação Básica contribuíram para a pesquisa. Foram utilizadas entrevistas semiestruturadas e observação não participante, as entrevistas foram analisadas com a utilização do Modelo da Estratégia Argumentativa (MEA). Verificou-se que suas representações  se objetivam em: mudar, melhorar, diferenciar e novidade e se ancoram em: novas tecnologias e construtivismo, elementos oriundos de sua formação inicial. Concluiu-se que os sujeitos participantes veem Inovação Pedagógica como algo externo a si e, por vezes, distante. Relacionam o termo à tecnologia, não se percebem como sujeitos promotores da inovação e apresentam vários entraves a uma prática pedagógica inovadora

The Negative Dimensional Oscillator at Finite Temperature

We study the thermal behavior of the negative dimensional harmonic oscillator of Dunne and Halliday that at zero temperature, due to a hidden BRST symmetry of the classical harmonic oscillator, is shown to be equivalent to the Grassmann oscillator of Finkelstein and Villasante. At finite temperature we verify that although being described by Grassmann numbers the thermal behavior of the negative dimensional oscillator is quite different from a Fermi system.Comment: 8 pages, IF/UFRJ/93/0

Microscopic Electron Models with Exact SO(5) Symmetry

We construct a class of microscopic electron models with exact SO(5) symmetry between antiferromagnetic and d-wave superconducting ground states. There is an exact one-to-one correspondence between both single-particle and collective excitations in both phases. SO(5) symmetry breaking terms can be introduced and classified according to irreducible representations of the exact SO(5) algebra. The resulting phase diagram and collective modes are identical to that of the SO(5) nonlinear sigma model.Comment: 5 pages, LATEX, 4 eps fig