Naturally light invisible axion in models with large local discrete symmetries

We show that by introducing appropriate local $Z_N(N\geq13)$ symmetries in electroweak models it is possible to implement an automatic Peccei-Quinn symmetry keeping at the same time the axion protected against gravitational effects. Although we consider here only an extension of the standard model and a particular 3-3-1 model, the strategy can be used in any kind of electroweak model. An interesting feature of this 3-3-1 model is that if: {\it i)} we add right-handed neutrinos, {\it ii)} the conservation of the total lepton number, and {\it iii)} a $Z_2$ symmetry, the $Z_{13}$ and the chiral Peccei-Quinn $U(1)_{\rm PQ}$ are both accidental symmetries in the sense that they are not imposed on the Lagrangian but they are just the consequence of the particle content of the model, its gauge invariance, renormalizability and Lorentz invariance. In addition, this model has no domain wall problem.Comment: Some changes and a new reference added, 7 page

Naturally light invisible axion and local Z_{13} times Z_3 symmetries

We show that by imposing local $Z_{13}\otimes Z_3$ symmetries in an $SU(2)\otimes U(1)$ electroweak model we can implement an invisible axion in such a way that (i) the Peccei-Quinn symmetry is an automatic symmetry of the classical Lagrangian; and (ii) the axion is protected from semi classical gravitational effects. In order to be able to implement such a large discrete symmetry, and at the same time allow a general mixing in each charge sector, we introduce right-handed neutrinos and enlarge the scalar sector of the model. The domain wall problem is briefly considered.Comment: PQ charges and typos correcte

Perfil sócio-econômico e tecnológico dos produtores de soja no Paraná.

Amostragenm e coleta dos dados; Modelo de analise; Analise e discussao dos dados: Distribuicao e uso da terra; Infra-estrutura economica e social; Mao-de-obra; Maquinas, equipamentos e animais; Sistemas de producao; Indicadores de administracao rural; Cooperativismo; Tecnologia e uso de insumos; Calcario; Fertilizantes; Adubacao verde; Descompactacao do solo; Metodos de manejo dos solos; Rotacao de culturas; Alternativas de inverno no Parana; Manipulacao de produtos quimicos; Uso de herbicidas e principais ervas daninhas; Pragas de soja e produtos quimicos utilizados; Doencas da soja e seu controle; Perdas na colheita; Sementes de soja.bitstream/item/77838/1/CNPSO-DOC.-38-89.pd

Monte Carlo Simulations of Ultrathin Magnetic Dots

In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an interesting behavior of the thermodynamic quantities as well as the vortex density.Comment: 10 figure

The Invisible Axion and Neutrino Masses

We show that in any invisible axion model due to the effects of effective non-renormalizable interactions related to an energy scale near the Peccei-Quinn, grand unification or even the Planck scale, active neutrinos necessarily acquire masses in the sub-eV range. Moreover, if sterile neutrinos are also included and if appropriate cyclic $Z_N$ symmetries are imposed, it is possible that some of these neutrinos are heavy while others are light.Comment: An example included and new references added. To appear in PR

Micotoxinas em amêndoas da castanheira-do-brasil.

Durante a palestra serão discutidos os problemas inerentes à presença de aflatoxinas na cadeia produtiva de castanha-do-brasil, os resultados obtidos durante o desenvolvimento do projeto e seu potencial impacto para a melhoria da qualidade deste produto