Unification of gauge couplings and the tau neutrino mass in Supergravity without R-parity

Minimal R-parity violating supergravity predicts a value for $alpha_s(M_Z)$ smaller than in the case with conserved R-parity, and therefore closer to the experimental world average. We show that the R-parity violating effect on the $alpha_s$ prediction comes from the larger two-loop b-quark Yukawa contribution to the renormalization group evolution of the gauge couplings which characterizes R-parity violating supergravity. The effect is correlated to the tau neutrino mass and is sensitive to the initial conditions on the soft supersymmetry breaking parameters at the unification scale. We show how a few percent effect on $alpha_s(M_Z)$ may naturally occur even with tau neutrino masses as small as indicated by the simplest neutrino oscillation interpretation of the atmospheric neutrino data from Super-Kamiokande.Comment: Latex, 21 pages including 2 figure

Incubação de ovos de codornas japonsesas em diferentes temperaturas: eclodibilidade, tempo de nascimento, peso ao nascer e mortalidade embrionária

A temperatura é o fator mais importante para o desenvolvimento embrionário, a eclodibilidade e o desempenho pós-nascimento de aves. A temperatura ideal é normalmente aquela que permite máxima eclodibilidade. Este trabalho verificou os efeitos de diferentes temperaturas de incubação sobre a eclodibilidade, perda de peso dos ovos, peso ao nascer, tempo de nascimento e mortalidade embrionária de ovos de codornas japonesas. Foram utilizados 800 ovos, divididos em oito grupos experimentais e incubados em diferentes temperaturas (34, 35, 36, 37, 38, 39, 40 e 41ºC).  As demais condições de incubação foram idênticas para todos os grupos, 60±5% de umidade relativa e viragem a cada 2 horas até a transferência para a nascedoura no 15º dia de incubação. A eclodibilidade dos ovos férteis foi maior para os ovos incubados a 37 e 38ºC; 76,6 e 80,7%, respectivamente. Os ovos incubados a 34ºC não eclodiram e os incubados a 35 e 41ºC apresentaram um índice muito baixo de eclodibilidade. As outras temperaturas proporcionaram eclodibilidade entre 50,3 e 57,7%. Os pesos ao nascer foram elevados nos grupos incubados em temperaturas altas (38-41°C) quando comparados aos grupos incubados em temperaturas baixas (35-37°C). Observou-se diferença no tempo de nascimento de acordo com a temperatura de incubação. A diferença de tempo entre o grupo de ovos que eclodiram mais cedo (40°C) e os ovos que eclodiram por último (35°C) foi de 156,3 horas ou 6,5 dias. Os embriões apresentaram-se resistentes a altas temperaturas até 40°C durante o período inicial da incubação, contudo o mesmo não foi observado nos estágios finais de incubação, quando altas temperaturas (39-41°C) aumentaram a mortalidade embrionária.Temperature is the most important factor affecting embryonic development, hatchability and post hatch performance. Optimum incubation temperature is normally defined as that required to achieve maximum hatchability. This work was carried out to verify the effects of different incubation temperatures on hatchability, hatch weight, hatch time and embryonic mortality of Japanese quail eggs. A total of 800 eggs were divided in eight experimental groups that were incubated at different temperatures (34, 35, 36, 37, 38, 39, 40 and 41ºC). The other incubation conditions were identical for all groups, 60±5% of relative humidity and egg turning every two hours until transference to the hatchers at 15 days of incubation. The results showed that fertile hatchability was higher for eggs incubated at 37 and 38ºC, 76.6 and 80.7%, respectively. Eggs incubated at 34ºC did not hatch and the ones incubated at 35 and 41ºC showed very poor hatchability. The other temperatures had hatch rates from 50.3 to 57.7%. There were higher hatch weights in eggs incubated at high temperatures (38-41°C) compared to the ones incubated at the lower ones (35-37°C). There was an enormous difference in the hatching time according to the incubation temperature. The difference of time between the groups of eggs that hatched earlier (40°C) compared to the ones the hatcher later (35°C) was 156.3 hours or 6.5 days. Embryos seemed to be resistant to at high temperatures until 40°C at the early period of incubation, however the same was not observed at the later stages of incubation when high temperatures (39-41°C) increased embryonic mortality

Probing neutrino properties with charged scalar lepton decays

Supersymmetry with bilinear R-parity violation provides a predictive framework for neutrino masses and mixings in agreement with current neutrino oscillation data. The model leads to striking signals at future colliders through the R-parity violating decays of the lightest supersymmetric particle. Here we study charged scalar lepton decays and demonstrate that if the scalar tau is the LSP (i) it will decay within the detector, despite the smallness of the neutrino masses, (ii) the relative ratio of branching ratios Br({tilde tau}_1 --> e sum nu_i)/ Br({tilde tau}_1 --> mu sum nu_i) is predicted from the measured solar neutrino angle, and (iii) scalar muon and scalar electron decays will allow to test the consistency of the model. Thus, bilinear R-parity breaking SUSY will be testable at future colliders also in the case where the LSP is not the neutralino.Comment: 24 pages, 8 ps figs Report-no.: IFIC/02-33 and ZU-TH 11/0

Solar Neutrino Masses and Mixing from Bilinear R-Parity Broken Supersymmetry: Analytical versus Numerical Results

We give an analytical calculation of solar neutrino masses and mixing at one-loop order within bilinear R-parity breaking supersymmetry, and compare our results to the exact numerical calculation. Our method is based on a systematic perturbative expansion of R-parity violating vertices to leading order. We find in general quite good agreement between approximate and full numerical calculation, but the approximate expressions are much simpler to implement. Our formalism works especially well for the case of the large mixing angle MSW solution (LMA-MSW), now strongly favoured by the recent KamLAND reactor neutrino data.Comment: 34 pages, 14 ps figs, some clarifying comments adde

Resultados preliminares com refratrômetro de alta resolução, usando sensor de frente de onda de Hartmann-Shack: parte I

In this project we are developing an instrument for measuring the wave-front aberrations of the human eye using the Hartmann-Shack sensor. A laser source is directed towards the eye and its diffuse reflection at the retina generates an approximately spherical wave-front inside the eye. This wave-front travels through the different components of the eye (vitreous humor, lens, aqueous humor, and cornea) and then leaves the eye carrying information about the aberrations caused by these components. Outside the eye there is an optical system composed of an array of microlenses and a CCD camera. The wave-front hits the microlens array and forms a pattern of spots at the CCD plane. Image processing algorithms detect the center of mass of each spot and this information is used to calculate the exact wave-front surface using least squares approximation by Zernike polynomials. We describe here the details of the first phase of this project, i. e., the construction of the first generation of prototype instruments and preliminary results for an artificial eye calibrated with different ametropias, i. e., myopia, hyperopia and astigmatism.Neste projeto estamos desenvolvendo instrumento para medidas das aberrações de frente de onda do olho humano usando um sensor Hartmann-Shack. Uma fonte de luz laser é direcionada ao olho e sua reflexão difusa na retina gera frente de onda aproximadamente esférica dentro do olho. Esta frente de onda atravessa os diferentes componentes do olho (humor vítreo, lente, humor aquoso e córnea) trazendo informações sobre as aberrações ópticas causadas por estes componentes. No meio externo ao olho existe sistema óptico formado por uma matriz de microlentes e uma câmera CCD. A frente de onda incide nesta matriz e forma um padrão aproximadamente matricial de spots no plano do CCD. Algoritmos de processamento de imagens são utilizados para detectar os centróides de cada spot e esta informação é utilizada para deduzir a forma da frente de onda usando métodos de aproximação por mínimos quadrados e polinômios de Zernike. Descrevemos aqui detalhes da primeira fase deste projeto, em que foi realizada a construção da primeira geração de instrumentos protótipos e testes preliminares em olho artificial, calibrado com diferentes ametropias, i. e., miopia, hipermetropia e astigmatismo.Eyetec Equipamentos Oftálmicos LtdaUniversidade Estadual de MaringáUniversidade de São Paulo Instituto de Física de São CarlosUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de OftalmologiaUNIFESP, EPM, Depto. de OftalmologiaSciEL

Broken R-parity, stop decays, and neutrino physics

We discuss the phenomenology of the lightest stop in models where R-parity is broken by bilinear superpotential terms. In this class of models we consider scenarios where the R-parity breaking two-body decay ~t_1->\tau^+b competes with the leading three-body decays such as ~t_1->W^+b~\chi^0_1. We demonstrate that the R-parity violating decay can be sizable and in some parts of the parameter space even the dominant one. Moreover we discuss the expectations for \~t_1->\mu^+b and ~t_1->e^+b. The recent results from solar and atmospheric neutrinos suggest that these are as important as the tau bottom mode. The \~t_1->l^+b decays are of particular interest for hadron colliders, as they may allow a full mass reconstruction of the lighter stop. Moreover these decay modes allow cross checks on the neutrino mixing angle involved in the solar neutrino puzzle complementary to those possible using neutralino decays. For the so--called small mixing angle or SMA solution ~t_1->e^+b should be negligible, while for the large mixing angle type solutions all ~t_1->l^+b decays should have comparable magnitude.Comment: 51 pages, 6 figures, LaTeX2e and RevTeX4, published versio

Reconciling neutrino anomalies in a simple four-neutrino scheme with R-parity violation

We propose a simple extension of the MSSM based on extra compact dimensions which includes an $SU(2) \otimes U(1)$ singlet superfield. The fermion present in this superfield is the sterile neutrino, which combines with one linear combination of $\nu_e-\nu_{\mu}-\nu_{\tau}$ to form a Dirac pair whose mass accounts for the LSND anomaly. Its small mass can be ascribed to a volume suppression factor associated with extra compact dimensions. On the other hand the sterile neutrino scalar partner can trigger the spontaneous violation of R-parity, thereby inducing the necessary mass splittings to fit also the solar and atmospheric neutrino data. Thus the model can explain all neutrino oscillation data. It leads to four predictions for the neutrino oscillation parameters and implies that the atmospheric neutrino problem must include at least some $\nu_{\mu} \to \nu_s$ oscillations, which will be testable in the near future. Moreover it also predicts that the lightest supersymmetric particle (LSP) decays visibly via lepton number violating modes, which could be searched for at present and future accelerators.Comment: 15 pages, requires axodraw.sty and elsart.cl