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Brazilian Journal of Physics, Volume: 34, Número: 4a, Publicado: 2004
  • Foreword

    Ferreira, Luiz Agostinho
  • New developments in the quantization of supersymmetric solitons (kinks, vortices and monopoles) Plenary Talks

    Rebhan, Anton; van Nieuwenhuizen, Peter; Wimmer, Robert

    Resumo em Inglês:

    We discuss the one-loop quantum corrections to the mass M and central charge Z of supersymmetric (susy) solitons: the kink, the vortex and the monopole. Contrary to previous expectations and published results, in each of these cases there are nonvanishing quantum corrections to the mass. For the N = 1 kink and the N = 2 monopole a new anomaly in Z rescues BPS saturation (M = Z); for the N = 2 vortex, BPS saturation is rescued for two reasons: (i) the quantum fluctuations of the Higgs field acquire a nontrivial phase due to the winding of the classical solution, and (ii) a fermionic zero mode used in the literature is shown not to be normalizable.
  • Jet tomography of quark gluon plasma Plenary Talks

    Wang, Xin-Nian

    Resumo em Inglês:

    Recent experimental measurements of high pT hadron spectra and jet correlation at RHIC are analyzed within a parton model which incoporates initial jet production and final propagation in heavy-ion collisions. The suppre-sion of single hadron spectra, back-to-back correlation, their centrality dependence and azimuthal anisotropy point to a dense matter with an initial parton density about 30 times of that in a cold heavy nucleus.
  • CP violation prospects at the LHC Plenary Talks

    Dijkstra, H. B.

    Resumo em Inglês:

    In the last few years experiments at B-factories have established CP violation in Bd decays. From 2007 onward new experiments will start to exploit the large <IMG SRC="/img/revistas/bjp/v34n4a/a04img21.gif">cross-section at the LHC to advance the understanding of CP violation by studying unprecedented large samples of all B-meson flavours. After a short review of the present status, the experimental challenges for the future experiments will be described. The emphasis will be on LHCb, a dedicated B-physics experiment at the LHC, and some examples of the projected physics results will be presented.
  • Inflation and precision cosmology Plenary Talks

    Martin, Jérôme

    Resumo em Inglês:

    A brief review of inflation is presented. After having demonstrated the generality of the inflationary mechanism, the emphasis is put on its simplest realization, namely the single field slow-roll inflationary scenario. Then, it is shown how, concretely, one can calculate the predictions of a given model of inflation. Finally, a short overview of the most popular models is given and the implications of the recently released WMAP data are briefly (and partially) discussed.
  • Applications of quantum field theory in condensed matter Round Table: What Is Up In Field Theory

    Marino, E. C.

    Resumo em Inglês:

    We present a brief review of some applications of quantum field theory in condensed matter systems. These include isotropic and anisotropic antiferromagnetic chains, strongly correlated organic conductors, such as the Bechgaard salts, carbon nanotubes and high-Tc superconductors. The review is by no means exhaustive and points to a vast range of new interesting possible applications.
  • Theoretical motivation for studying superstrings Round Table: What Is Up In Field Theory

    Berkovits, Nathan

    Resumo em Inglês:

    I try to explain why many high-energy theoretical physicists are studying superstrings.
  • Remarks on noncommutative field theories Round Table: What Is Up In Field Theory

    Gomes, M.

    Resumo em Inglês:

    Some of the motivations and basic properties of noncommutative field models are presented. I also comment on recent developments in the understanding of these peculiar and intriguing theories.
  • Color superconductivity, BPS Zk strings and monopole confinement in N = 2 and N = 4 super Yang-Mills theories Parallel Talks

    Kneipp, Marco A. C.

    Resumo em Inglês:

    We review some recent developments on BPS string solutions and monopole confinement in the Higgs (or color) superconducting phase of <IMG SRC="/img/revistas/bjp/v34n4a/caln_mai.gif" > or = 2 and <IMG SRC="/img/revistas/bjp/v34n4a/caln_mai.gif" > or = 4 super Yang-Mills theories. In particular, the monopole magnetic fluxes are shown to be always integer linear combinations of string fluxes. Moreover, a bound for the threshold length of the string breaking is obtained. When the gauge group SU(N) is broken to Z N, the BPS string tension satisfies the Casimir scaling law. Furthermore, in the SU(3) case the string solutions are such that they allow the formation of a confining system with three monopoles.
  • Conceptual problems in quantum field theory Parallel Talks

    Wreszinski, Walter F.

    Resumo em Inglês:

    We review some conceptual problems in quantum field theory, with an emphasis on exact results and open problems.
  • Noncommutative solitons and instantons Parallel Talks

    Schaposnik, Fidel A.

    Resumo em Inglês:

    I review different approaches to the construction of vortex and instanton solutions in noncommutative field theories.
  • Cosmic topology: a brief overview Parallel Talks

    Rebouças, M. J.; Gomero, G. I.

    Resumo em Inglês:

    Questions such as whether we live in a spatially finite universe, and what its shape and size may be, are among the fundamental open problems that high precision modern cosmology needs to resolve. These questions go beyond the scope of general relativity (GR), since as a (local) metrical theory GR leaves the global topology of the universe undetermined. Despite our present-day inability to predict the topology of the universe, given the wealth of increasingly accurate astro-cosmological observations it is expected that we should be able to detect it. An overview of basic features of cosmic topology, the main methods for its detection, and observational constraints on detectability are briefly presented. Recent theoretical and observational results related to cosmic topology are also discussed.
  • Non gravitational black holes Parallel Talks

    De Lorenci, V. A.; Klippert, R.

    Resumo em Inglês:

    Analogue models of general relativity have recently been considered with great interest by the scientific community. They connect branches of physics as different as gravitation, condensed matter physics, electrodynamics, acoustics, and quantum field theory. One of the main expectations about such models lies on the possibility of testing in laboratory some aspects of quantum field theory in curved spacetimes. For instance, it seems to be possible to probe the existence of Hawking radiation by means of analogue models in the context of certain condensed matter systems. We briefly report the present day status of this topic of research. Some specific models are considered, particularly those presenting analogue event horizons as solutions. The issue of thermal emission (analogue Hawking radiation) is also discussed.
  • Selected topics in teleparallel gravity Parallel Talks

    Aldrovandi, R.; Pereira, J. G.; Vu, K. H.

    Resumo em Inglês:

    Teleparallel gravity can be seen as a gauge theory for the translation group. As such, its fundamental field is neither the tetrad nor the metric, but a gauge potential assuming values in the Lie algebra of the translation group. This gauge character makes of teleparallel gravity, despite its equivalence to general relativity, a rather peculiar theory. A first important point is that it does not rely on the universality of free fall, and consequently does not require the equivalence principle to describe the gravitational interaction. Another peculiarity is its similarity with Maxwell's theory, which allows an Abelian nonintegrable phase factor approach, and consequently a global formulation for gravitation. Application of these concepts to the motion of spinless particles, as well as to the COW and gravitational Aharonov-Bohm effects are presented and discussed.
  • The next e+ e- linear collider Parallel Talks

    Maciel, Arthur K. A.

    Resumo em Inglês:

    Following the recent realization by the worldwide high energy physics community for the need of a next generation e+ e- collisions machine, we review the main reasons for such a proposal, and the current status of that endeavor. General aspects of the physics program, the collider itself, and its detectors are covered.
  • Pierre Auger Observatory: status report Parallel Talks

    Oliveira, M. A. L. de

    Resumo em Inglês:

    The Pierre Auger Observatory is a large international effort to provide measurements of extensive air showers (EAS) initiated in the upper atmosphere by cosmic rays with energies above 10(18) eV , the Ultra High Energy Cosmic Rays (UHECR's). The explanations for the origin, acceleration processes and composition of the UHECR's face theoretical and experimental difficulties, due to the extremely low flux in this energy region. The full observatory will consist of a hybrid detector using an array of 1600 water <IMG SRC="/img/revistas/bjp/v34n4a/a16img01.gif">erenkov tanks spread over an area of 3000 km² overlooked by a set of 4 air fluorescence detectors per site. The southern site is being instrumented in Argentina and I will discuss its present status in this paper.
  • Scalar meson sigma phase motion at D+-> pi- pi+pi+ decay Parallel Talks

    Bediaga, Ignacio

    Resumo em Inglês:

    We make a direct and model-independent measurement of the low pi+ pi- mass phase motion in the D+ <FONT FACE=Symbol>® p</FONT>-pi+pi+ decay. Our preliminary results show a strong phase variation, compatible with the isoscalar sigma(500) meson. This result confirms our previous result [1] where we found evidence for the existence of this scalar particle using full Dalitz-plot analysis. We apply the Amplitude Difference (AD) method [2] to the same Fermilab E791 data sample used in the preceding analysis. We also give an example of how we extract the phase motion of the scalar amplitude, looking at the f0(980) in Ds+ <FONT FACE=Symbol>® p</FONT>-pi+pi+ decay.
  • QCD at high parton density Parallel Talks

    Gonçalves, V. P.

    Resumo em Inglês:

    The high parton density regime of Quantum Chromodynamics (QCD) is briefly discussed. Some phenomenological aspects of saturation are described, mainly focusing on possible signatures of the non-linear QCD dynamics in electron-proton/nucleus collisions. Implications of these effects in central and ultraperipheral heavy-ion collisions are also presented.
  • KamLAND data and the solution to the solar neutrino problem Parallel Talks

    Holanda, P. C. de; Smirnov, A. Yu.

    Resumo em Inglês:

    The first KamLAND results are in a very good agreement with the predictions made on the basis of the solar neutrino data and the LMA realization of the MSW mechanism. We perform a combined analysis of the KamLAND (rate, spectrum) and the solar neutrino data with a free boron neutrino flux fB. The best fit values of neutrino parameters are deltam² = 7.1.10-5 eV², tan² theta = 0.40 and fB = 1.04 with the 1sigma intervals: deltam² = (6.4 - 8.4). 10-5 eV², tan² theta = 0.33 - 0.48. We find the 3sigma upper bounds: deltam² < 1.7 . 10-4 eV² and tan² theta< 0.64, and the lower bound deltam² > 4.8 . 10-5 eV². In the best fit point we predict for SNO: CC/NC = <IMG SRC="/img/revistas/bjp/v34n4a/a19img01.gif">and <IMG SRC="/img/revistas/bjp/v34n4a/a19img02.gif" > or = 3.0 ± 0.8% (68% C.L.), and <IMG SRC="/img/revistas/bjp/v34n4a/a19img02.gif">< 6% at the 3sigma level. Further improvements in the determination of the oscillation parameters are discussed and implications of the solar neutrino and KamLAND results are considered.
  • Search for supersymmetry at the LHC Parallel Talks

    Mercadante, P. G.

    Resumo em Inglês:

    It is generally accepted that the LHC is the accelerator facility at which weak scale supersymmetry will either be discovered or definitely excluded. I give a brief introduction to weak scale supersymmetry presenting the general argument that limit the supersymmetrical spectrum to be below TeV energies. We will see that the LHC is able to search for supersymmetry in several of its realization far above the expected spectrum masses. However, in the last section we will see some well motivated scenarios where supersymmetric sparticles might be very heavy, thus beyond the LHC reach. Such scenarios deserve a more detailed study to push the LHC reach.
  • Neutrinos at 1%: a reactor based measurement of theta13 Round Table

    Reyna, David

    Resumo em Inglês:

    Past studies of neutrinos and the recent results on neutrino mixing have opened up many new possibilities as well as the understanding that neutrino mixing is very different from the better known quark mixing. The last remaining unmeasured component of the neutrino mixing matrix (Ue3) also provides a window to understanding neutrino matter effects, the mass hierarchy, and the possibility of measuring leptonic CP violation. A discussion of the benefits and difficulties of pursuing such a measurement with reactor neutrinos will be presented. In addition, possible sites for such an experiment will be discussed, including a location in Brazil.
  • Cosmology and gravitation Summary Talks

    Maia, M. D.

    Resumo em Inglês:

    This is a brief summary with comments on selected contributions to the Cosmology and Gravitation section at the 24th Brazilian Meeting on Particle and Fields (ENFPC XXIV), held at Caxambu, from September 30 to October 4, 2003.
  • Particle physics phenomenology Summary Talks

    Ducati, Maria Beatriz Gay

    Resumo em Inglês:

    We give a summary of contributed talks and papers in the plenary, parallel and poster sessions of the XXIV ENFPC (Brazilian National Meeting on Particles and Fields) in the area of particle phenomenology.
  • Experimental high energy physics Summary Talks

    Paula, Leandro de

    Resumo em Inglês:

    A summary of the contributions on experimental high energy physics to the XXIV Brazilian National Meeting on Particle and Fields is presented. There were 5 invited talks and 32 submitted contributions. The active Brazilian groups are involved in several interesting projects but suffer from the lack of funding and interaction with Brazilian theorists.
  • Field theory Summary Talks

    Bazeia, Dionisio

    Resumo em Inglês:

    We offer a summary of the talks, oral communications and posters presented at the field theory section of the XXIV Brazilian National Meeting on Particles and Fields.
  • Homenagem à Professora Elisa Frota-Pessôa

  • Local persistence and blocking in the two-dimensional blume-capel model Regular Articles

    Silva, Roberto da; Dahmen, S. R.

    Resumo em Inglês:

    In this paper we study the local persistence of the two-dimensional Blume-Capel Model by extending the concept of Glauber dynamics. We verify that for any value of the ratio alpha = D/J between anisotropy D and exchange J the persistence shows a power law behavior. In particular for alpha < 0 we find a persistence exponent thetal = 0:2096(13), i.e. in the Ising universality class. For alpha > 0 (<FONT FACE=Symbol>a ¹</FONT> 1) we observe the occurrence of blocking.
  • Exciton polariton emission from a resonantly excited GaAs microcavity Regular Articles

    Cotta, E. A.; Ribeiro Filho, H. P.; Matinaga, F. M.; Cury, L. A.; Moreira, M. V. B; Rodrigues, W. N.; Oliveira, A. G. de

    Resumo em Inglês:

    Coherent emission efficiency in a 100Å GaAs SQW microcavity was enhanced one order when pumped resonantly at 10 K, compared to the off-resonant excitation. The usual kink observed in the exciton emission linewidth as well as in the emission intensity in relation to the pump power, changes smoothly instead of the usual abrupt kink observed in the off-resonant microcavity laser. In addition, polarization measurements show a correlation relationship between the pump light polarization and the cavity emission polarization.
  • Seasonal cusp radiation belt on dayside magnetosphere Regular Articles

    Pugacheva, G.I.; Gusev, A.A.; Jayanthi, U.B.; Schuch, N.J.; Choque, K.T.

    Resumo em Inglês:

    The possibility of quasi-stable trapping of charged particles of hundreds keV to MeV energy on the frontside Earth magnetosphere is explored in by numerical modeling of the single particle orbits in the geomagnetic field utilizing empirical Tsyganenko magnetic field model. Due to solar wind pressure the remote magnetic field lines on the frontside of the magnetosphere exhibit two minima in the geomagnetic field strength along the field line in high latitudes on the both sides of the equator. These minima may result in stable confinement structures, a kind of radiation belts, in the northern or/and the southern hemispheres, providing energetic particle trapping for times from several minutes to duration of seasonal scale. Simulation of energetic proton orbits passing through the regions of the magnetic field minima with different disturbance level and the Earth's tilt reveals conditions in which these trapped radiation zones could result. It is shown that the existence of the adiabatic confinement zones strongly depends on the seasonal inclination of the Earth's rotation axis. As a result the northern cusp confinement zone appears only in a summer solstice and similarly the southern cusp capture zone appears only in a winter solstice. In equinox time the confinement zones exist in both hemispheres in the disturbed magnetospheric conditions, however, they are less pronounced. The zones are essentially restricted to the sunlit magnetosphere. They form a kind of cusp radiation ring/belt, where a proton drifts with a period of several minutes, conserving its 1st and the 2nd adiabatic invariants. The latitudinal width of the ring is very thin, about 2-5 latitudinal degrees. The proton orbits passing through the off-equatorial field minimum opposite to those cusp belts reveal another interesting effect: a bound of the geomagnetic equatorial plane on the day sector. These and other features of the confinement zones in the two minima off-equatorial magnetic field regions are discussed.
  • Quantum atom optics with trapped Bose-Einstein condensates Regular Articles

    Olsen, M. K.

    Resumo em Inglês:

    Both Bose-Einstein condensates and optical fields are composed of bosons, so that the majority of the processes which have long been studied in quantum and nonlinear optics have equivalents in the field of Bose-Einsten condensation. However, due to the masses of the condensed atoms, the confining potentials and the huge collisional nonlinearities, the simpler theoretical approaches common to quantum optics can sometimes give misleading answers when applied to condensates. In this work we describe some of the areas where simplified treatments can be misleading, and compare and contrast the predictions of quantum many-body treatments with those of the single-mode type treatments which have been so successful in quantum optics.
  • Intensity dependence for trap loss rate in a magneto-optical trap of strontium Regular Articles

    Caires, A. R. L.; Telles, G. D.; Mancini, M. W.; Marcassa, L. G.; Bagnato, V. S.; Wilkowski, D.; Kaiser, R.

    Resumo em Inglês:

    We have measured the collisional loss rate for cold strontium atoms held in a magneto-optical trap as a function of light intensity in the regime of low intensity (2-6 mW/cm²). The results confirm our recently proposed model, where we showed that the sudden increase of loss rate at low intensities does not depend on hyperfine structure changing collision only. The model, which is based on radiative escape mechanism and a light intensity dependent escape velocity, is able to reproduce quite well the behavior of the experimental observations. The data here reported may be of importance for a recent proposed application for cold trapped 88Sr atoms, as well as other trappable alkaline earth metal atoms such as Ca.
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