The Glauber-Sudarshan and Kirkwood-Rihaczec functions

It is shown how to write the Kirkwood-Rihaczec quasiprobability distribution as an expectation value of the vacuum state. We do this, by writing the position eigenstates as a "displacment" of the vacumm. We also give a relation between the Glauber-Sudarshan and Kirkwood-Rihaczec quasiprobability distributions

Age determination of the HR8799 planetary system using asteroseismology

Discovery of the first planetary system by direct imaging around HR8799 has made the age determination of the host star a very important task. This determination is the key to derive accurate masses of the planets and to study the dynamical stability of the system. The age of this star has been estimated using different procedures. In this work we show that some of these procedures have problems and large uncertainties, and the real age of this star is still unknown, needing more observational constraints. Therefore, we have developed a comprehensive modeling of HR8799, and taking advantage of its gamma Doradus-type pulsations, we have estimated the age of the star using asteroseismology. The accuracy in the age determination depends on the rotation velocity of the star, and therefore an accurate value of the inclination angle is required to solve the problem. Nevertheless, we find that the age estimate for this star previously published in the literature ([30,160] Myr) is unlikely, and a more accurate value might be closer to the Gyr. This determination has deep implications on the value of the mass of the objects orbiting HR8799. An age around $\approx$ 1 Gyr implies that these objects are brown dwarfs.Comment: 5 pages, 3 figures, accepted in MNRAS Letter

A new record of fossil wood of Vochysiaceae from the Upper Pleistocene (Arroyo Feliciano Formation), Argentina, South America

A new species of Qualeoxylon Suguio & Mussa is described from the Late Pleistocene Arroyo Feliciano Formation of the Gualeguay Basin on eastern Argentina. It is the second record of this genus in South America and was previously only known from Late Eocene to Early Miocene (late Pleistocene for some authors) on the Itaquaquecetuba Formation, São Paulo, Brazil. This new fossil species was recovered in the Consorcio Paso Sociedad fossil locality (Federal, Entre Ríos, Argentina). Wood anatomical features suggest a close relationship with Vochysiaceae and is an affi nity with the extant genus Qualea. This fossil wood is consistent with the warm and humid climate inferred for this region during the upper Pleistocene. The discovery of Qualeoxylon in Arroyo Feliciano Formation supports the hypothesis that the Vochysiaceae was more widespread in the past than today.Uma nova espécie de Qualeoxylon Suguio & Mussa é descrita para a Formação Arroyo Feliciano Bacia Gualeguay, Pleistoceno fi nal no leste da Argentina. É o segundo registro desse gênero na América do Sul, até agora só conhecido para o Eoceno Superior a Mioceno Inferior (Pleistoceno Superior para alguns autores) da Formação Itaquaquecetuba, São Paulo, Brasil. O espécime aqui estudado foi coletado na localidade fossilífera Consorcio Paso Sociedad (Federal, Entre Ríos, Argentina). As características anatômicas da madeira sugerem uma relação com a família Vochysiaceae e uma afi nidade com o atual gênero Qualea. Esta madeira fóssil condiz com o clima quente e úmido inferido para esta região durante o Pleistoceno fi nal. A descoberta de Qualeoxylon na Formação Arroyo Feliciano apoia a ideia de que a família Vochysiaceae foi mais amplamente distribuída no passado que nos dias atuais.Fil: Moya, Eliana Vanesa. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Brea, Mariana. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentin

Polarized Deformed Nuclei Studied via Coincidence Polarized Electron Scattering: The case of 21 Ne

Coincidence reactions of the type \svec{A}(\svec{e},e'N)B involving the scattering of polarized electrons from deformed polarized targets are discussed within the context of the plane--wave impulse approximation. A general expression for the polarized spectral function for transitions leaving the residual nucleus in discrete states is presented. General properties and angular symmetries exhibited by the polarization observables are discussed in detail. Results for unpolarized cross sections as well as for polarization ratios (asymmetries) are obtained for typical quasi--free kinematics. The dependences of the polarization observables on the bound neutron momentum, target polarization orientation, nuclear deformation and value of the momentum transfer $q$ are discussed in detail for various different kinematical situations.Comment: 37 pages in Plain TeX, MIT-CTP-209