Realizing the supersymmetric inverse seesaw model in the framework of R-parity violation

If, on one hand, the inverse seesaw is the paradigm of TeV scale seesaw mechanism, on the other it is a challenge to find scenarios capable of realizing it. In this work we propose a scenario, based on the framework of R-parity violation, that realizes minimally the supersymmetric inverse seesaw mechanism. In it the energy scale parameters involved in the mechanism are recognized as the vacuum expectation values of the scalars that compose the singlet superfields $\hat N^C$ and $\hat S$. We develop also the scalar sector of the model and show that the Higgs mass receives a new tree-level contribution that, when combined with the standard contribution plus loop correction, is capable of attaining $125$GeV without resort to heavy stops.Comment: Minor modification of the text. Final version to be published in PL

Bounds on the Simplest Little Higgs Model Mass Spectrum Through Z Leptonic Decay

We derive the leptonic neutral current in the simplest little Higgs model and compute the contribution of the model to the decay width $Z \to e^+e^-$. Using the precision electroweak data we obtain a strong lower bound $f\geq 5.6$ TeV at 95% C.L. on the characteristic energy scale of the model. It results in a lower bound for the new gauge bosons $W^{\prime\pm}$ and $Z^{\prime}$ as being $M_{W^{\prime\pm}}\geq 2.6$ TeV and $M_{Z^{\prime}}\geq 3.1$ TeV, respectively. We also present the allowed values of the $k=f_1/f_2$ which is the parameter relating the two vacuum expectation values of the scalar triplets in the model, and the $\mu$ parameter of a quadratic term, involving the triplets, necessary to provide an acceptable mass range for the standard Higgs boson.Comment: New references added, 13 pages. Version to be publishe

The Left-Right SU(3)(L)xSU(3)(R)xU(1)(X) Model with Light, keV and Heavy Neutrinos

We construct a full left-right model for the electroweak interactions based on the $SU(3)_{L}\otimes SU(3)_{R}\otimes U(1)_{X}$ gauge symmetry. The fermion content of the model is such that anomaly cancellation restricts the number of families to be a multiple of three. One of the most important features of the model is the joint presence of three light active neutrinos, three additional neutrinos at keV mass scale, and six heavy ones with masses around\textbf{$10^{11}$} GeV. They form a well-motivated part of the spectrum in the sense they address challenging problems related to neutrino oscillation, warm dark matter, and baryogenesis through leptogenesis.Comment: 11 pages. Small corrections and typos fixed. Accepted for publication in PR

Diversidade, síndromes de dispersão e formas de vida vegetal em diferentes estágios sucessionais de florestas secundárias em Tomé-Açu, Pará, Brasil.

Florestas secundárias (capoeiras) são formas de vegetação resultantes de processos sucessionais determinados pelo histórico de uso da terra, distância de florestas primárias bem como fatores estocásticos. O estágio sucessional pode indicar quais as formas de vida vegetal e as síndromes de dispersão dominantes no ambiente. Neste estudo foram avaliados: uma floresta primária (controle) e florestas secundárias de 25, 10 e 5 anos no município de Tomé-Açu, Pará, Brasil. A primeira apresentou 224 espécies e a floresta secundária de cinco anos teve 91, a menor quantidade. O número de espécies diferiu entre ambientes (&#967;2 = 59,6; p <0,001), mas não a quantidade de famílias (&#967;2 = 3,6; p = 0,305). O índice de Shannon-Weaner foi alto para todas as florestas, exceto para a capoeira de cinco anos. A distribuição de formas de vida e as síndromes de dispersão diferiram para todas as capoeiras quando comparadas com as distribuições observadas na floresta primária. As formas arbustivas predominaram na capoeira de cinco anos e as arbóreas nas demais. As espécies zoocóricas foram as mais frequentes, enquanto que as autocóricas e hidrocóricas as mais comuns na floresta primária. Devido às boas condições de diversidade das florestas secundárias de Tomé-Açu, sugerimos ações para um manejo florestal sustentável visando retornos econômicos e a conservação destes ambientes