Leptogenesis and Low energy CP violation, a link

How is CP violation of low energy related to CP violation required from baryon number asymmetry ? We give an example which shows a direct link between CP violation of neutrino oscillation and baryogenesis through leptogenesis.Comment: 3 pages and 2 figures, Talk presented at 4th Nufac02, July 1-6, 200

CP violation in neutrino oscillation and leptogenesis

We study the correlation between CP violation in neutrino oscillations and leptogenesis in the framework with two heavy Majorana neutrinos and three light neutrinos. Among three unremovable CP phases, a heavy Majorana phase contributes to leptogenesis. We show how the heavy Majorana phase contributes to Jarlskog determinant $J$ as well as neutrinoless double $\beta$ decay by identifying a low energy CP violating phase which signals the CP violating phase for leptogenesis. For some specific cases of the Dirac mass term of neutrinos, a direct relation between lepton number asymmetry and $J$ is obtained. For the most general case of the framework, we study the effect on $J$ coming from the phases which are not related to leptogenesis, and also show how the correlation can be lost in the presence of those phases.Comment: 4 pages and 3 figure

Suscetibilidade a inseticidas e parasitismo natural por Trichogramma sp. em Traça-do-tomateiro.

A traça-do-tomateiro é uma praga importante do tomate e inseticidas são freqüentemente empregados para o seu controle. Porém, devido ao impacto ambiental e a possibilidade de resistência aos produtos utilizados para o controle do inseto, o controle biológico com o uso de Trichogramma pode ser uma alternativa para eliminar os dois problemas. Neste trabalho foi avaliada em bioensaios de laboratório a eficiência da dose recomendada de inseticidas do grupo químico dos organofosforados, piretróides e benzoiluréia para o controle da traça-do-tomateiro. Foi também avaliada a ocorrência natural de Trichogramma sp. em áreas pulverizadas ou não pulverizadas com inseticidas. A ocorrência do parasitismo natural foi determinada por meio da coleta de folhas em campo contendo ovos de traça-do-tomateiro, a fim de determinar, em avaliações de laboratório, a percentagem de ovos parasitados. Os resultados mostraram que todos os inseticidas testados causaram uma mortalidade de larvas menor que 70%, o que sugere uma eficiência reduzida dos produtos. O parasitóide Trichogramma sp. ocorreu naturalmente em todas as áreas, mas a percentagem de parasitismo foi menor nas áreas pulverizadas. Outros estudos devem ser realizados a fim de avaliar o potencial dos parasitóides locais, provavelmente mais bem adaptados as condições locais, para o controle da traça-do-tomateiro. Se esses organismos forem efetivos, o uso de inseticidas em lavouras de tomate pode ser reduzido.bitstream/CNPH-2009/33237/1/bpd_28.pd

Neutrino Large Mixing in Universal Yukawa Coupling Model with Small Violation

We have analyzed the possibility that the universal Yukawa coupling (democratic mass matrix) with small violations of Dirac and Majorana neutrinos can induce the large mixing of neutrinos through the seesaw mechanism. The possibility can be achieved by the condition that the violation parameters of Majorana neutrinos are sufficiently smaller than the violation parameters of Dirac neutrinos. Allowed regions of the violation parameters producing the observed neutrino mass hierarchy and large neutrino mixing are not so restricted at present in contrast to the violation parameters for quark sector.Comment: 14 pages, 4figure

Small violations of unitarity, the phase in Bs mixing and visible t->cZ decays at the LHC

We show that it is possible to accommodate the observed size of the phase in $B^0_s$--$\bar B^0_s$, mixing in the framework of a model with violation of $3\times 3$ unitarity. This violation is associated to the presence of a new $Q=2/3$ isosinglet quark $T$, which mixes both with $t$ and $c$ and has a mass not exceeding 500 GeV. The crucial point is the fact that this framework allows for $\chi\equiv\arg(-V_{ts}V_{cb}V_{tb}^*V_{cs}^*)$ of order $\lambda$, to be contrasted with the situation in the Standard Model, where $\chi$ is constrained to be of order $\lambda^2$. We point out that this scenario implies rare top decays $t\to cZ$ at a rate observable at the LHC and $|V_{tb}|$ significantly different from unity. In this framework, one may also account for the observed size of $D^0$--$\bar D^0$ mixing without having to invoke long distance contributions. It is also shown that in the present scenario, the observed size of $D^0$--$\bar D^0$ mixing constrains $\chi^\prime\equiv\arg(-V_{cd}V_{us}V_{cs}^*V_{ud}^*)$ to be of order $\lambda^4$, which is significantly smaller than what is allowed in generic models with violations of $3\times 3$ unitarity.Comment: 20 pages. References added. Additional observables considered, updated numerical examples, conclusions unchange

Construção em altura com MLCC

Com o objetivo de dar resposta aos problemas identificados nas soluções e propostas já conhecidas, e como parte resultante de uma investigação sobre a construção em altura com MLCC a decorrer na Escola de Engenharia da Universidade do Minho (EEUM), encontra-se em desenvolvimento o Urban Timber System (UT System)

Non-universal behavior for aperiodic interactions within a mean-field approximation

We study the spin-1/2 Ising model on a Bethe lattice in the mean-field limit, with the interaction constants following two deterministic aperiodic sequences: Fibonacci or period-doubling ones. New algorithms of sequence generation were implemented, which were fundamental in obtaining long sequences and, therefore, precise results. We calculate the exact critical temperature for both sequences, as well as the critical exponent $\beta$, $\gamma$ and $\delta$. For the Fibonacci sequence, the exponents are classical, while for the period-doubling one they depend on the ratio between the two exchange constants. The usual relations between critical exponents are satisfied, within error bars, for the period-doubling sequence. Therefore, we show that mean-field-like procedures may lead to nonclassical critical exponents.Comment: 6 pages, 7 figures, to be published in Phys. Rev.