Efeitos de campos elétrico e magnético em um sistema dissipativo pulsante

The main idea of this work is to understand and analyze the dynamical aspects of the motion of a particle moving in the annular billiard, which corresponds to two circles of radius R and r (r-elastic) cases. When we introduce magnetic and electric fields, the particle is submitted to the Lorentz force. It also can suffer successive collisions with the breathing circles, winning or losing energy. For the elastic time-dependent case, we have already observed that a particle can gain unlimited energy. The purpose of this work is to study the effects of both external fields in the mean energy of the system, for the time-dependent case with and without dissipation. Our initial results conduct us to believe that electrical field can contribute to the increasing of mean energy, and a magnetic field applied to the vertical axis of coordinate (what guarantees the particle do not travel away the billiard’s plane) uses to arrest the particle to the whispering gallery orbits and do not contribute to the Fermi acceleration indeed. However, in presence of the electric field, to same values, the magnetic one together can improve this referred process, obtaining greater energy values to the same number of iterations. These results are applied to the concentric case, that was reported did not haven any significant energy gain on the free particle motion

Controle e caos na formação de moléculas com pulso de laser

We investigate the formation of molecules under the action of external field acting during the atomic collision. To describe this process, the collision of atomic pairs, we use the Morse oscillator model driven The study was developed from the standpoint of classical mechanics by analyzing the sensitivity of the system with respect to initial conditions, the verification of chaotic dynamics associated with the process of formation of molecules with laser and analysis of system dynamics and the likelihood of photoassociation in response to the external field parameters

Efeitos da equação de estado em hidrodinâmica relativística através de alguns observáveis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Corpos (con) sentidos: cartografando processos de subjetivação de produto(re)s de corporalidades singulares

Pós-graduação em Psicologia - FCLAS

Estudo de manobras evasivas com perturbações orbitais

Pós-graduação em Física - FEG

Transcrição cooperativa de genes ribossomais em Escherichia coli usando um modelo estocástico e dependente de sequência

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propriedades estatísticas de bilhares abertos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Termodinâmica do modelo Bouncer: um gás unidimensional simplificado

Pós-graduação em Física - IGCE

Termodinâmica de um conjunto de partículas em um bilhar bidimensional dependente do tempo: um gás bidimensional simplificado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aplicação de um jogo digital e análise de conceitos da teoria cinética dos gases

Pós-graduação em Educação para a Ciência - FC

Drag force in a strongly coupled anisotropic plasma

We calculate the drag force experienced by an in finitely massive quark propagating at constant velocity through an anisotropic, strongly coupled N = 4 plasma by means of its gravity dual. We find that the gluon cloud trailing behind the quark is generally misaligned with the quark velocity, and that the latter is also misaligned with the force. The drag coefficient mu can be larger or smaller than the corresponding isotropic value depending on the velocity and the direction of motion. In the ultra-relativistic limit we find that generically mu proportional to p. We discuss the conditions under which this behaviour may extend to more general situations.

Jet quenching in a strongly coupled anisotropic plasma

The jet quenching parameter of an anisotropic plasma depends on the relative orientation between the anisotropic direction, the direction of motion of the parton, and the direction along which the momentum broadening is measured. We calculate the jet quenching parameter of an anisotropic, strongly coupled N = 4 plasma by means of its gravity dual. We present the results for arbitrary orientations and arbitrary values of the anisotropy. The anisotropic value can be larger or smaller than the isotropic one, and this depends on whether the comparison is made at equal temperatures or at equal entropy densities. We compare our results to analogous calculations for the real-world quark-gluon plasma and find agreement in some cases and disagreement in others.

Direct photon production in p plus p collisions at root s=200 GeV at midrapidity

The differential cross section for the production of direct photons in p + p collisions at root s = 200 GeV at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive direct photons were measured in the transverse momentum range from 5: 5-25 GeV/c, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus x(T), the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.

Positron collisions with ethene

We present experimental and theoretical cross sections for positron collisions with ethene molecules. The experimental total cross sections (TCSs) were obtained with a linear transmission technique, for energies from 0.1 eV up to 70 eV. The calculations employed the Schwinger multichannel method and were performed in the static plus polarization approximation for energies up to 10 eV. Our calculated elastic cross sections indicate a Ramsauer-Townsend minimum around 2.8 eV and a virtual state, in agreement with previous calculations by da Silva et al. [Phys. Rev. Lett. 77, 1028 (1996)]. We found reasonable agreement between the calculated elastic integral cross section and the measured total cross section below the positronium formation threshold. The present results are also in quite good agreement with available theoretical and experimental data, although for the experiments this is only true for TCSs above about 7 eV.