Neutrino Decay and Neutrinoless Double Beta Decay in a 3-3-1 Model

In this work we show that the implementation of spontaneous breaking of the lepton number in the 3-3-1 model with right-handed neutrinos gives rise to fast neutrino decay with majoron emission and generates a bunch of new contributions to the neutrinoless double beta decay.Comment: Version accepted for publication in the Phys. Rev.

Efeito da aplicação de herbicidas no teor de carotenóides em milho verde.

Na cultura do milho, o uso de herbicidas é prática de elevada importância para a obtenção de altos rendimentos de grãos, porém, alguns grupos recomendados inibem a biossíntese de carotenóides, trazendo preocupações para programas de melhoramento que visam a obtenção de genótipos de milho com maiores teores desses compostos, cujas propriedades biológicas como precursores de pró-vitamina A e antioxidantes são importantes para a saúde humana. Portanto, o objetivo do presente trabalho foi avaliar a influência da aplicação de herbicidas no teor de carotenóides em grãos de milho verde. O plantio foi conduzido em campo experimental do Centro Nacional de Pesquisa de Milho e Sorgo da Embrapa, localizado em Sete Lagoas, MG, no ano agrícola de 2007, utilizando-se o híbrido simples BRS 1030. As aplicações químicas foram feitas com herbicidas pós-emergentes totalizando 5 tratamentos: sem aplicação; foramsulfuron + iodosulfuron-metyl-sodium (40 g/ha-1); nicosulfuron (20 g/ha-1) ; mesotrione (120 g/ha-1) e tembotrione (100 g/ha-1). Todos os tratamentos herbicidas constituíram mistura com atrazine a 1000 g/ha-1 Os grãos verdes foram avaliados quanto aos teores a-caroteno, ß-caroteno, luteína, zeaxantina e ß-criptoxantina através de cromatografia líquida de alta eficiência (CLAE). A partir dos resultados foram calculados os teores de carotenóides totais (CT), total de carotenóides pró-vitamina A (Pro-VA) e o percentual dos carotenóides em relação a CT. O delineamento utilizado foi o inteiramente casualizado com cinco tratamentos e duas repetições. A aplicação dos herbicidas em pós-emergência nas doses do estudo não resultaram em reduções nos teores de carotenóides, embora tenham sido detectadas diferenças na composição dos grãos verdes entre os tratamentos para luteína, ß-caroteno e a-caroteno. Os resultados permitem concluir que os herbicidas mesotrione, tembotrione, foramsulfuron + iodosulfurom-metyl-sodium e nicosulfuron, recomendados para a cultura do milho, não afetam negativamente a composição de carotenóides em grãos de milho verde

Avaliação de genótipos de girassol na região do Planalto Médio do Rio Grande do Sul na safra 2005/2006.

bitstream/CNPT-2010/40322/1/p-bp49.pd

Comparison of 120Sn(6He,6He)120Sn and 120Sn(alpha,alpha)120Sn elastic scattering and signatures of the 6He neutron halo in the optical potential

Cross sections of $^{120}$Sn($\alpha$,$\alpha$)$^{120}$Sn elastic scattering have been extracted from the $\alpha$ particle beam contamination of a recent $^{120}$Sn($^6$He,$^6$He)$^{120}$Sn experiment. Both reactions are analyzed using systematic double folding potentials in the real part and smoothly varying Woods-Saxon potentials in the imaginary part. The potential extracted from the $^{120}$Sn($^6$He,$^6$He)$^{120}$Sn data may be used as the basis for the construction of a simple global $^6$He optical potential. The comparison of the $^6$He and $\alpha$ data shows that the halo nature of the $^6$He nucleus leads to a clear signature in the reflexion coefficients $\eta_L$: the relevant angular momenta $L$ with $\eta_L \gg 0$ and $\eta_L \ll 1$ are shifted to larger $L$ with a broader distribution. This signature is not present in the $\alpha$ scattering data and can thus be used as a new criterion for the definition of a halo nucleus.Comment: 13 pages, 7 figures, accepted for publication in Phys. Rev.

Minimal 3-3-1 model, lepton mixing and muonium-antimuonium conversion

The recent experimental results on neutrino oscillation and on muonium-antimuonium conversion require extension of the minimal 3-3-1 model. We review the constraints imposed to the model by those measurements and suggest a pattern of leptonic mixing, with charged leptons in a non-diagonal basis, which accounts for the neutrino physics and circumvents the tight muonium-antimuonium bounds on the model. We also illustrate a scenario where this pattern could be realized.Comment: 4 pages; abbreviated version, conclusions unchange

Remark on the vectorlike nature of the electromagnetism and the electric charge quantization

In this work we study the structure of the electromagnetic interactions and the electric charge quantization in gauge theories of electroweak interactions based on semi-simple groups. We show that in the standard model of the electroweak interactions the structure of the electromagnetic interactions is strongly correlated to the quantization pattern of the electric charges. We examine these two questions also in all possible chiral bilepton gauge models of the electroweak interactions. In all they we can explain the vectorlike nature of the electromagnetic interactions and the electric charge quantization together demanding nonvanishing fermion masses and the anomaly cancellations.Comment: 17 pages, latex, no figure

The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This is accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of the lepton number. We identify the Majoron as a singlet under $SU_L(2)\otimes U_Y(1)$ symmetry, which makes it safe under the current bounds imposed by electroweak data. The main result of this work is that the seesaw mechanism works already at TeV scale with the outcome that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analysis concerning detection sensitivity at LHC, we conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure