Time-dependent Mechanics and Lagrangian submanifolds of Dirac manifolds

A description of time-dependent Mechanics in terms of Lagrangian submanifolds of Dirac manifolds (in particular, presymplectic and Poisson manifolds) is presented. Two new Tulczyjew triples are discussed. The first one is adapted to the restricted Hamiltonian formalism and the second one is adapted to the extended Hamiltonian formalism

Bianchi Cosmologies: New Variables and a Hidden Supersymmetry

We find a supersymmetrization of the Bianchi IX cosmology in terms of Ashtekar's new variables. This provides a framework for connecting the recent results of Graham and those of Ryan and Moncrief for quantum states of this model. These states are also related with the states obtained particularizing supergravity for a minisuperspace. Implications for the general theory are also briefly discussed.Comment: 15 Pages, RevTex, NSF-ITP-93-9

The XMM spectral catalog of SDSS optically selected Seyfert 2 galaxies

We present an X-ray spectroscopic study of optically selected (SDSS) Seyfert 2 (Sy2) galaxies. The goal is to study the obscuration of Sy2 galaxies beyond the local universe, using good quality X-ray spectra in combination with high S/N optical spectra for their robust classification. We analyzed all available XMM-Newton archival observations of narrow emission line galaxies that meet the above criteria in the redshift range 0.05<z<0.35. We initially selected narrow line AGN using the SDSS optical spectra and the BPT classification diagram. We further modeled and removed the stellar continuum, and we analyzed the residual emission line spectrum to exclude any possible intermediate-type Seyferts. Our final catalog comprises 31 Sy2 galaxies with median redshift z~0.1. X-ray spectroscopy is performed using the available X-ray spectra from the 3XMM and the XMMFITCAT catalogs. Implementing various indicators of obscuration, we find seven (~23%) Compton-thick AGN. The X-ray spectroscopic Compton-thick classification agrees with other commonly used diagnostics, such as the X-ray to mid-IR luminosity ratio and the X-ray to [OIII] luminosity ratio. Most importantly, we find four (~13%) unobscured Sy2 galaxies, at odds with the simplest unification model. Their accretion rates are significantly lower than the rest of our Sy2 sample, in agreement with previous studies that predict the absence of the broad line region below a certain Eddington ratio threshold.Comment: 12 pages, 6 figures, accepted for publication in A&

Contenido polínico de la familia Pinaceae en la atmósfera de Córdoba, España

XV lnternational A.P.L.E. Symposium of Palynolog

Dynamics of momentum entanglement in lowest-order QED

We study the dynamics of momentum entanglement generated in the lowest-order QED interaction between two massive spin-1/2 charged particles, which grows in time as the two fermions exchange virtual photons. We observe that the degree of generated entanglement between interacting particles with initial well-defined momentum can be infinite. We explain this divergence in the context of entanglement theory for continuous variables, and show how to circumvent this apparent paradox. Finally, we discuss two different possibilities of transforming momentum into spin entanglement, through dynamical operations or through Lorentz boosts.Comment: 10 pages and 7 figures. Accepted in PR

On the Hamilton-Jacobi Theory for Singular Lagrangian Systems

We develop a Hamilton-Jacobi theory for singular lagrangian systems using the Gotay-Nester-Hinds constraint algorithm. The procedure works even if the system has secondary constraints.Comment: 36 page