Phenomenological Consequences of sub-leading Terms in See-Saw Formulas

Several aspects of next-to-leading (NLO) order corrections to see-saw formulas are discussed and phenomenologically relevant situations are identified. We generalize the formalism to calculate the NLO terms developed for the type I see-saw to variants like the inverse, double or linear see-saw, i.e., to cases in which more than two mass scales are present. In the standard type I case with very heavy fermion singlets the sub-leading terms are negligible. However, effects in the percent regime are possible when sub-matrices of the complete neutral fermion mass matrix obey a moderate hierarchy, e.g. weak scale and TeV scale. Examples are cancellations of large terms leading to small neutrino masses, or inverse see-saw scenarios. We furthermore identify situations in which no NLO corrections to certain observables arise, namely for mu-tau symmetry and cases with a vanishing neutrino mass. Finally, we emphasize that the unavoidable unitarity violation in see-saw scenarios with extra fermions can be calculated with the formalism in a straightforward manner.Comment: 22 pages, matches published versio

Seesaw Neutrino Signals at the Large Hadron Collider

We discuss the scenario with gauge singlet fermions (right-handed neutrinos) accessible at the energy of the Large Hadron Collider. The singlet fermions generate tiny neutrino masses via the seesaw mechanism and also have sizable couplings to the standard-model particles. We demonstrate that these two facts, which are naively not satisfied simultaneously, are reconciled in the five-dimensional framework in various fashions, which make the seesaw mechanism observable. The collider signal of tri-lepton final states with transverse missing energy is investigated for two explicit examples of the observable seesaw, taking account of three types of neutrino mass spectrum and the constraint from lepton flavor violation. We find by showing the significance of signal discovery that the collider experiment has a potential to find signals of extra dimensions and the origin of small neutrino masses.Comment: 27 pages, 4 figure

Right-handed Sneutrino Dark Matter in Supersymmetric B-L Model

We show that the lightest right-handed sneutrino in TeV scale supersymmetric B-L model with inverse seesaw mechanism is a viable candidate for cold dark matter. We find that it accounts for the observed dark matter relic abundance in a wide range of parameter space. The spin-independent cross section of B-L right-handed sneutrino is consistent with the recent results CDMS II and XENON experiments and it is detectable in future direct detection experiments. Although the B-L right-handed sneutrinos annihilate into leptons, the PAMELA results can not be explained in this model unless a huge boost factor is considered. Also the muon flux generated by B-L right-handed sneutrino in the galactic center is smaller than Super-Kamiokande's upper bound.Comment: 16 pages, 7 figures; version accepted for publication in Journal of High Energy Physic

Produção de melão Cantaloupe influenciado por coberturas do solo, agrotêxtil e lâminas de irrigação Melon yield and fruit quality as influenced by soil coverages, agrotextile and irrigation depth in dry season

Dois experimentos foram conduzidos simultaneamente em uma mesma área, no município de Baraúna (RN), de outubro a dezembro de 2003, com o objetivo de estudar o uso de cobertura do solo com filmes plásticos e lâminas de irrigação, bem como o uso de agrotêxtil, na produção de melão Cantaloupe. Em um experimento foi utilizado o agrotêxtil, enquanto no outro não. Em cada experimento estudou-se o efeito de cinco coberturas (solo descoberto, cobertura com plástico preto, prateado, amarelo e marrom) e três lâminas de irrigação (100%, 84% e 67% da lâmina padrão de 270 mm, L1), em esquema fatorial 5 x 3, no delineamento de blocos casualizados completos com duas repetições. Foram avaliados o número, massa média e produtividade de frutos comercializáveis (mercados interno e externo), refugos e totais. O uso do agrotêxtil aumentou o número de frutos e produtividade. Na ausência do agrotêxtil, a cobertura do solo com plástico amarelo aumentou a produtividade comercial em relação ao solo descoberto, enquanto que, na presença do agrotêxtil o plástico preto foi superior ao marrom, mas não diferiu do solo descoberto. A produção diminuiu com a redução da lâmina de irrigação. O uso do agrotêxtil associado ao uso de cobertura do solo com plástico preto ou solo descoberto apresentou maior viabilidade econômica.<br>Two experiments were carried out at the same time in Baraúna, Rio Grande do Norte State, Brazil, from October to December 2004, to evaluate different soil coverages and irrigation depth as well as the use of agrotextile on the melon yield. In the first experiment the agrotextile was used, but not in the second one. Both experiments were designed in a 5 x 3 factorial scheme in randomized complete blocks with two replications. The treatments of the factorial consisted of the combination of five soil coverages (films of yellow, brown, black and silvered polyethylene, and no soil coverages) with three irrigation depths (100%, 84% and 67% of the standard water amount). The fruit number, mean fruit mass, marketable fruit yield, refused and total fruit yield were evaluated. The treatments with film of yellow polyethylene increased the marketable fruit yield in the absence of agrotextile. The fruit yield decreased with decreasing irrigation depths. The treatments with black polyethylene film or with nude soil associated with agrotextile had the best economic results