Confining potential in a color dielectric medium with parallel domain walls

We study quark confinement in a system of two parallel domain walls interpolating different color dielectric media. We use the phenomenological approach in which the confinement of quarks appears considering the QCD vacuum as a color dielectric medium. We explore this phenomenon in QCD_2, where the confinement of the color flux between the domain walls manifests, in a scenario where two 0-branes (representing external quark and antiquark) are connected by a QCD string. We obtain solutions of the equations of motion via first-order differential equations. We find a new color confining potential that increases monotonically with the distance between the domain walls.Comment: RevTex4, 5 pages, 1 figure; version to appear in Int. J. Mod. Phys.

Timing the millisecond pulsars in 47 Tucanae

In the last 10 years 20 millisecond pulsars have been discovered in the globular cluster 47 Tucanae. Hitherto, only 3 of these had published timing solutions. Here we improve upon these 3 and present 12 new solutions. These measurements can be used to determine a variety of physical properties of the pulsars and of the cluster. The 15 pulsars have positions determined with typical uncertianties of only a few milliarcsec and they are all located within 1.2 arcmin of the cluster centre. We have also measured the proper motions of 5 of the pulsars, which are consistent with the proper motion of 47 Tuc based on Hipparcos data. The period derivatives measured for many of the pulsars are dominated by the dynamical effects of the cluster gravitational field, and are used to constrain the surface mass density of the cluster. All pulsars have characteristic ages T > 170 Myr and magnetic fields B < 2.4e9 Gauss, and the average T > 1 Gyr. We have measured the rate of advance of periastron for the binary pulsar J0024-7204H, implying a total system mass 1.4+-0.8 solar masses.Comment: 17 pages, 11 included figures, accepted for publication in MNRA

Tecnologia de aplicação de defensivos agrícolas.

Defensivos agrícolas. Alvo biológico e químico. Formulação dos defensivos agrícolas. Vias de intoxicação. Métodos de aplicação de defensivos agrícolas. Fatores fundamentais em uma aplicação de defensivos. Equipamentos de proteção individual (E. P. I.). Preparo e aplicação da calda. Fatores que influenciam nas pulverizações. Regulagem e calibração de um pulverizador de barras. Perdas por deriva. Perdas por evaporação. Manutenção de pulverizadores. Primeiros socorros. Avanços no desenvolvimento de novos equipamentos. Considerações finais.bitstream/CNPAT-2010/10340/1/Dc-102.pd

Dimensional Crossover and Finite Size Scaling Below T_c

Using the formalism developed in [1] dimensional crossover in an Ising type system below T_c(L) is considered, T_c(L) being the critical temperature of the finite size system. The crossover considered is that on a d dimensional layered system satisfying periodic boundary conditions and of size L. Effective critical exponents δ_eff and β_eff are introduced and shown to crossover between their d and d -1 dimensional values for ξ→∞ in the limits L/ξ_L→∞ and L/ξ_L→0 respectively, ξ_L being the correlation length in the layers. The effective exponents are shown to satisfy natural generalizations of the standard scaling laws. L dependent, global, non-linear scaling fields which span the entire crossover are defined and a scaling form of the equation of state in terms of them derived from an L dependent renormalization group equation. A universal crossover equation of state and effective exponents are obtained to one loop and shown in the above asymptotic limits to reduce to known results

Finite temperature phase transitions in quantum field theory

Using the formalism developed in [1] we discuss finite temperature quantum field theory in the high temperature regime T >> m_T where m_T represents a generic finite temperature mass in the theory. In particular we consider λϕ⁴ theory in four dimensions showing perturbatively that it has a non-trivial fixed point at finite temperature, the relevant anomalous dimensions near the second-order phase transition being three-dimensional ones. We emphasize the importance of having renormalization schemes and a renormalization group (RG) equation that can explicitly take into account the fact that the degrees of freedom of a theory may be qualitatively different at different scales

Dimensional Reduction and the Non-triviality of λϕ⁴ in Four Dimensions at High Temperature

It is shown to one loop that a λϕ⁴ theory contracts from being a non-renormalizable theory above four dimensions to a renormalizable theory in the limit of zero size of the additional dimensions above four. This provides an example of the decoupling of an infinite number of modes in the infrared domain of the theory. The results have applications to statistical mechanical systems above the critical point in the context of finite size effects, and Kaluza Klein theories in high energy physics