Study of the lepton flavor-violating Z′→τμZ'\to\tau\mu decay

The lepton flavor violating $Z^{\prime}\to\tau\mu$ decay is studied in the context of several extended models that predict the existence of the new gauge boson named $Z^\prime$. A calculation of the strength of the lepton flavor violating $Z^\prime\mu\tau$ coupling is presented by using the most general renormalizable Lagrangian that includes lepton flavor violation. We used the experimental value of the muon magnetic dipole moment to bound this coupling, from which the $\mathrm{Re}(\Omega_{L\mu\tau}\Omega^\ast_{R\mu\tau})$ parameter is constrained and it is found that $\mathrm{Re}(\Omega_{L\mu\tau}\Omega^\ast_{R\mu\tau})\sim 10^{-2}$ for a $Z^\prime$ boson mass of 2 TeV. Alongside, we employed the experimental restrictions over the $\tau\to\mu\gamma$ and $\tau\to\mu\mu^+\mu^-$ processes in the context of several models that predict the existence of the $Z^\prime$ gauge boson to bound the mentioned coupling. The most restrictive bounds come from the calculation of the three-body decay. For this case, it was found that the most restrictive result is provided by a vector-like coupling, denoted as $|\Omega_{\mu\tau}|^2$, for the $Z_\chi$ case, finding around $10^{-2}$ for a $Z^\prime$ boson mass of 2 TeV. We used this information to estimate the branching ratio for the $Z^\prime\to\tau\mu$ decay. According to the analyzed models the least optimistic result is provided by the Sequential $Z$ model, which is of the order of $10^{-2}$ for a $Z^\prime$ boson mass around 2 TeV.Comment: Revised versio

CP-odd static electromagnetic properties of the W gauge boson and the t quark via the anomalous tbW coupling

In the framework of the electroweak chiral Lagrangian, the one-loop induced effects of the anomalous $tbW$ coupling, which includes both left- and right-handed complex components, on the static electromagnetic properties of the $W$ boson and the $t$ quark are studied. The attention is focused mainly on the CP-violating electromagnetic properties. It is found that the $tbW$ anomalous coupling can induce both CP-violating moments of the $W$ boson, namely, its electric dipole ($\tilde{\mu}_W$) and magnetic quadrupole ($\tilde{Q}_W$) moments. As far as the $t$ quark is concerned, a potentially large electric dipole moment $(d_t)$ can arise due to the anomalous $tbW$ coupling. The most recent bounds on the left- and right-handed parameters from $B$ meson physics lead to the following estimates $\tilde{\mu}_W ~ 10^{-23}-10^{-22}$ e-cm and $\tilde{Q}_W~ 10^{-38}-10^{-37}$ e-cm$^2$, which are 7 and 14 orders of magnitude larger than the standard model (SM) predictions, whereas $d_t$ may be as large as $10^{-22}$ e-cm, which is about 8 orders of magnitude larger than its SM counterpart.Comment: This paper has been merged with hep-ph/0612171 for publication in Physical Review

Electric dipole and magnetic quadrupole moments of the WW boson via a CP-violating HWWHWW vertex in effective Lagrangians

The possibility of nonnegligible $W$ electric dipole ($\widetilde{\mu}_W$) and magnetic quadrupole ($\widetilde{Q}_W$) moments induced by the most general $HWW$ vertex is examined via the effective Lagrangian technique. It is assumed that new heavy fermions induce an anomalous CP-odd component of the $HWW$ vertex, which can be parametrized by an $SU_L(2)\times U_Y(1)$-invariant dimension-six operator. This anomalous contribution, when combined with the standard model CP-even contribution, lead to CP-odd electromagnetic properties of the $W$ boson, which are characterized by the form factors $\Delta \widetilde{\kappa}$ and $\Delta \widetilde{Q}$. It is found that $\Delta \widetilde{\kappa}$ is divergent, whereas $\Delta \widetilde{Q}$ is finite, which reflects the fact that the latter cannot be generated at the one-loop level in any renormalizable theory. Assuming reasonable values for the unknown parameters, we found that $\widetilde{\mu}_W\sim 3-6\times 10^{-21}$ e-cm, which is eight orders of magnitude larger than the SM prediction and close to the upper bound derived from the neutron electric dipole moment. The estimated size of the somewhat less-studied $\widetilde{Q}_W$ moment is of the order of $-10^{-36}$ e-cm^2, which is fifteen orders of magnitude above the SM contribution.Comment: 7 pages, 6 figures, REVTEX styl

Aplicação de Membranas Amnióticas na Reconstrução da Superfície Ocular Externa em Idade Pediátrica

Introdução: Vários estudos comprovam os benefícios da aplicação de membranas amnióticas na reconstrução da superfície ocular em idade adulta, pelos seus efeitos anti-inflamatorios, anti-adesivos e anti-apoptóticos. Em idade pediátrica, a reconstrução da superfície ocular carece de especial atenção e este procedimento encontra-se ainda pouco estudado. Não foi encontrado nenhum estudo especificamente dirigido à aplicação de membranas amnióticas na reconstrução da superfície ocular externa desta faixa etária, pelo que procurámos elucidá-lo. Material e métodos: Estudo retrospetivo englobando todos os doentes em idade pediátrica (7,1 anos +/- 4,17) submetidos a transplante de membrana amniótica no Centro Hospitalar de Lisboa Central entre 2008 e 2015, para reconstrução da superfície ocular externa. Entre os doentes (n=6 olhos de 6 crianças), quatro apresentavam patologia do foro neoformativo ou inflamatório e dois apresentavam queimaduras extensas da superfície ocular. Foi realizada divisão em dois grupos, com base na presença ou não de insuficiência de células limbares. Foram avaliadas características clínicas e demográficas, MAVC antes e após a cirurgia, tempo de reepitelização, amplitude de movimentos oculares antes e após a cirurgia, presença de recidiva ou complicações e resultado estético. O tempo de seguimento foi de 4 a 83 meses. Resultados: Verificaram-se sucessos completos em todos os doentes sem insuficiência limbar (50% do total de doentes), sucessos parciais em dois dos doentes com insuficiência limbar (33,3%) e um caso de falência terapêutica (16.7%). Nos doentes em que se observou recidiva, o tempo médio para esta ocorrência foi de 8,3 +/- 6,8 meses. Não se verificaram complicações em nenhum dos casos. Observou-se melhoria pós-operatória em um dos dois casos que tinham diminuição da acuidade visual pré-operatória (aumento da MAVC em 6 linhas). Verificou-se ainda uma melhoria da motilidade ocular e aspeto estético em todos os doentes com alterações prévias destes parâmetros. Conclusão: O transplante de membrana amniótica mostrou ser muito benéfico também em idade pediátrica. Pode ser realizado como tratamento isolado ou coadjuvante, sendo os resultados superiores nos casos de células limbares funcionantes. Não foi detetada maior incidência de complicações ou rejeições comparativamente ao descrito na literatura para a idade adulta.info:eu-repo/semantics/publishedVersio

Gauge invariance and radiative corrections in an extra dimensional theory

The gauge structure of the four dimensional effective theory originated in a pure five dimensional Yang-Mills theory compactified on the orbifold $S^1/Z_2$, is discussed on the basis of the BRST symmetry. If gauge parameters propagate in the bulk, the excited Kaluza-Klein (KK) modes are gauge fields and the four dimensional theory is gauge invariant only if the compactification is carried out by using curvatures as fundamental objects. The four dimensional theory is governed by two types of gauge transformations, one determined by the KK zero modes of the gauge parameters and the other by the excited ones. Within this context, a gauge-fixing procedure to quantize the KK modes that is covariant under the first type of gauge transformations is shown and the ghost sector induced by the gauge-fixing functions is presented. If the gauge parameters are confined to the usual four dimensional space-time, the known result in the literature is reproduced with some minor variants, although it is emphasized that the excited KK modes are not gauge fields, but matter fields transforming under the adjoint representation of $SU_4(N)$. A calculation of the one-loop contributions of the excited KK modes of the electroweak gauge group on the off-shell WWV, with V a photon or a Z boson, is exhibited. Such contributions are free of ultraviolet divergences and well-behaved at high energies.Comment: 7 pages, conference proceedings, a new reference was added, the title has been change

Ex-nihilo II: Examination Syllabi and the Sequencing of Cosmology Education

Cosmology education has become an integral part of modern physics courses. Directed by National Curricula, major UK examination boards have developed syllabi that contain explicit statements about the model of the Big Bang and the strong observational evidence that supports it. This work examines the similarities and differences in these specifications, addresses when cosmology could be taught within a physics course, what should be included in this teaching and in what sequence it should be taught at different levels.Comment: 9 pages. Accepted for publication in a special issue of Physics Educatio

Methods for assessment of keel bone damage in poultry

Keel bone damage (KBD) is a critical issue facing the laying hen industry today as a result of the likely pain leading to compromised welfare and the potential for reduced productivity. Recent reports suggest that damage, while highly variable and likely dependent on a host of factors, extends to all systems (including battery cages, furnished cages, and non-cage systems), genetic lines, and management styles. Despite the extent of the problem, the research community remains uncertain as to the causes and influencing factors of KBD. Although progress has been made investigating these factors, the overall effort is hindered by several issues related to the assessment of KBD, including quality and variation in the methods used between research groups. These issues prevent effective comparison of studies, as well as difficulties in identifying the presence of damage leading to poor accuracy and reliability. The current manuscript seeks to resolve these issues by offering precise definitions for types of KBD, reviewing methods for assessment, and providing recommendations that can improve the accuracy and reliability of those assessment