Transverse Lattice QCD in 2+1 Dimensions

Following a suggestion due to Bardeen and Pearson, we formulate an effective light-front Hamiltonian for large-N gauge theory in (2+1)-dimensions. Two space-time dimensions are continuous and the remaining space dimension is discretised on a lattice. Eguchi-Kawai reduction to a (1+1)-dimensional theory takes place. We investigate the string tension and glueball spectrum, comparing with Euclidean Lattice Monte Carlo data.Comment: 4 pages LaTeX with 2 Postscript figures, uses boxedeps.tex and e spcrc2.sty. Poster session contribution to LATTICE96(poster). Minor changes in new versio

Renormalization of an effective Light-Cone QCD-inspired theory for the Pion and other Mesons

The renormalization of the effective QCD-Hamiltonian theory for the quark-antiquark channel is performed in terms of a renormalized or fixed-point Hamiltonian that leads to subtracted dynamical equations. The fixed point-Hamiltonian brings the renormalization conditions as well as the counterterms that render the theory finite. The approach is renormalization group invariant. The parameters of the renormalized effective QCD-Hamiltonian comes from the pion mass and radius, for a given constituent quark mass. The 1s and excited 2s states of $\bar u q$ are calculated as a function of the mass of the quark $q$ being s, c or b, and compared to the experimental values.Comment: 39 pages, 10 figure

SISTEMA SEPARADOR DE ITENS UTILIZANDO RFID

TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia Mecatrônica.A logística é assunto muito discutido nos últimos anos por ser questão primordial para empresas que buscam mais velocidade e menos custo em suas linhas de produção. Assim, há uma grande procura por sistemas automatizados para auxiliar nas produções industriais. A construção de um sistema separador de itens utilizando RFID se destina a setores industriais com o objetivo de tornar o processo de separação de itens mais rápido, confiável e de baixo custo. A ferramenta de identificação por rádio frequência é uma tendência que está crescendo muito na última década, vindo à tona e substituindo outros meios de identificação. O processo de construção inicia pela parte estrutural, estrutura da esteira, passando pela parte de hardware, como kits e componentes eletrônicos, e finalizando ao software, que compreende a programação dos mesmos para possibilitar as devidas funções atribuídas ao sistema separador de itens. O sistema entra em funcionamento no momento que passar um item com seu cartão de identificação próximo ao sensor, e assim, estabelecer comunicação sem fio, utilizando ZigBee com o LabVIEW, para acesso ao banco de dados identificando qual destino do produto e, assim, realizar as devidas separações no instante que o mesmo chegar próximo as hastes seletoras

"Every human life is worth the same, and worth saving.": Ethical and Psychological Issues in the Harry Potter Series

openNel mondo della letteratura per bambini molti sono i libri ad aver raggiunto un grande successo, tanto da diventare dei best seller. Tra di essi, è di notevole importanza la saga della scrittrice inglese J.K. Rowling, Harry Potter, che ha contribuito a cambiare il panorama socio-culturale globale, tanto da essere considerata un vero e proprio fenomeno. La saga non ha avuto un forte impatto solo nel mondo della letteratura, ma anche in quello del marketing, del cinema e del turismo. È interessante come la scrittrice sia riuscita, all’interno di una storia fantasy, ad introdurre e trattare tematiche delicate e attuali quali il razzismo, la schiavitù, la disparità di genere, i disturbi psichici e la disabilità.In the world of children’s literature many are the books which achieved great success, so as to become great classics. Among them, it is important to mention the importance of J.K. Rowling’s saga, Harry Potter, which changed the socio-cultural global landscape. The saga is considered a phenomenon, since it not only had a great impact in the world of literature, but also in that of marketing, cinema and tourism. It is interesting how the writer managed to introduce, within a fantasy saga, important and delicate themes such as racism, slavery, gender disparity, psychological illnesses and disability

La comunidad senegalesa de A Coruña: un estudio comparativo de las relaciones intra e interétnicas, las identidades y los imaginarios sociales con las comunidades marroquí y camerunesa

Traballo fin de mestrado (UDC.SOC). Migracións internacionais: investigación, políticas migratorias e mediación intercultural. Curso 2008/200

Effect of Zero Modes on the Bound-State Spectrum in Light-Cone Quantisation

We study the role of bosonic zero modes in light-cone quantisation on the invariant mass spectrum for the simplified setting of two-dimensional SU(2) Yang-Mills theory coupled to massive scalar adjoint matter. Specifically, we use discretised light-cone quantisation where the momentum modes become discrete. Two types of zero momentum mode appear -- constrained and dynamical zero modes. In fact only the latter type of modes turn out to mix with the Fock vacuum. Omission of the constrained modes leads to the dynamical zero modes being controlled by an infinite square-well potential. We find that taking into account the wavefunctions for these modes in the computation of the full bound state spectrum of the two dimensional theory leads to 21% shifts in the masses of the lowest lying states.Comment: LaTeX with 5 postscript file

Density perturbations in general modified gravitational theories

We derive the equations of linear cosmological perturbations for the general Lagrangian density $f (R,\phi, X)/2+L_c$, where $R$ is a Ricci scalar, $\phi$ is a scalar field, and $X=-(\nabla \phi)^2/2$ is a field kinetic energy. We take into account a nonlinear self-interaction term $L_c$ recently studied in the context of "Galileon" cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasi-static approximation on sub-horizon scales. We also derive conditions for the avoidance of ghosts and Laplacian instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature and thus it is convenient to test the viability of such models from both theoretical and observational points of view.Comment: 17 pages, no figure

A non-uniqueness problem of the Dirac theory in a curved spacetime

The Dirac equation in a curved spacetime depends on a field of coefficients (essentially the Dirac matrices), for which a continuum of different choices are possible. We study the conditions under which a change of the coefficient fields leads to an equivalent Hamiltonian operator H, or to an equivalent energy operator E. We do that for the standard version of the gravitational Dirac equation, and for two alternative equations based on the tensor representation of the Dirac fields. The latter equations may be defined when the spacetime is four-dimensional, noncompact, and admits a spinor structure. We find that, for each among the three versions of the equation, the vast majority of the possible coefficient changes do not lead to an equivalent operator H, nor to an equivalent operator E, whence a lack of uniqueness. In particular, we prove that the Dirac energy spectrum is not unique. This non-uniqueness of the energy spectrum comes from an effect of the choice of coefficients, and applies in any given coordinates.Comment: 35 pages (standard article format). v4: Version accepted for publication in Annalen der Physik: Redactional improvements and precisions added in Section 2. Footnote added in the Conclusion, with new references. v3: Introduction and Conclusion reinforced. References added. v2: subsection 2.3 added: the Lagrangian and the spin group. Also, added explanations on admissible coefficient change

Tube Model for Light-Front QCD

We propose the tube model as a first step in solving the bound state problem in light-front QCD. In this approach we neglect transverse variations of the fields, producing a model with 1+1 dimensional dynamics. We then solve the two, three, and four particle sectors of the model for the case of pure glue SU(3). We study convergence to the continuum limit and various properties of the spectrum.Comment: 29 page