Physical regularization for the spin-1/2 Aharonov-Bohm problem in conical space

We examine the bound state and scattering problem of a spin-one-half particle undergone to an Aharonov-Bohm potential in a conical space in the nonrelativistic limit. The crucial problem of the \delta-function singularity coming from the Zeeman spin interaction with the magnetic flux tube is solved through the self-adjoint extension method. Using two different approaches already known in the literature, both based on the self-adjoint extension method, we obtain the self-adjoint extension parameter to the bound state and scattering scenarios in terms of the physics of the problem. It is shown that such a parameter is the same for both situations. The method is general and is suitable for any quantum system with a singular Hamiltonian that has bound and scattering states.Comment: Revtex4, 5 pages, published versio

Zoneamento de aptidão climática para a videira europeia no Estado do Piauí.

bitstream/item/80699/1/documento-194.pd

Zoneamento de risco climático para a cultura da soja no Estado do Piauí.

Introdução; Modelo de balanço hídrico; Modelo de espacialização; Mapas de risco climático; Conclusões.bitstream/item/37184/1/Doc167.pd

Aspectos econômicos em sistemas de produção com culturas alimentares para agricultores de baixa renda na Microrregião Bragantina, Pará.

bitstream/item/28816/1/CPATU-BP6.pd

Gauge Theories with Lorentz-Symmetry Violation by Symplectic Projector Method

The violation of Lorentz symmetry is studied from the point of view of a canonical formulation. We make the usual analysis on the constraints structure of the Carroll-Field-Jackiw model. In this context we derive the equations of motion for the physical variables and check out the dispersion relations obtained from them. Therefore, by the analysis using Symplectic Projector Method (SPM), we can check the results about this type of Lorentz breaking with those in the recent literature: in this sense we can confirm that the configuration of $v^{\mu}$ space-like is stable, and the $v^{\mu}$ time-like carry tachionic modes.Comment: 7 pages and no figure

Zoneamento de risco climático para a cultura do sorgo granífero no Estado do Piauí.

bitstream/item/95325/1/DOC1780001.pd