Chiral kinetic theory from the on-shell effective theory: derivation of collision terms

We show that the on-shell effective theory (OSEFT) is the quantum field theory counterpart of a Foldy-Wouthuysen diagonalization of relativistic quantum mechanics for massless fermions. Thus, it is free of the Zitterbewegung oscillations that would yield an ill-defined meaning to the semiclassical transport approach at short distances if derived from the pure Dirac picture. We present a detailed derivation of the collision terms in the chiral kinetic theory using the OSEFT. Collision integrals are derived up to order 1/E, where E is the energy of an on-shell fermion. At this order, the collision terms depends on the spin tensor of the fermion, and in the presence of chiral imbalance, it describes how a massless fermion of a given helicity interacts differently with the transverse photons of different circular polarization. In order to back up our results, we check that they allow us to reproduce the fermion decay rate in an ultradegenerate plasma with a chiral imbalance computed directly from QED.Comment: 36 pages, 2 figures, title and abstract modified, version largely extended with more details and discussions, results and conclusions unchange

Ultrafast Transfer and Transient Entrapment of Photoexcited Mg Electron in Mg@C-60

Electron relaxation is studied in endofullerene Mg@C-60 after an initial localized photoexcitation in Mg by nonadiabatic molecular dynamics simulations. Two approaches to the electronic structure of the excited electronic states are used: (i) an independent particle approximation based on a density-functional theory description of molecular orbitals and (ii) a configuration-interaction description of the many-body effects. Both methods exhibit similar relaxation times, leading to an ultrafast decay and charge transfer from Mg to C-60 within tens of femtoseconds. Method (i) further elicits a transient trap of the transferred electron that can delay the electron-hole recombination. Results shall motivate experiments to probe these ultrafast processes by two-photon transient absorption or photoelectron spectroscopy in gas phase, in solution, or as thin films

RADS: una herramienta para reutilizar estrategias en diseños de arquitecturas de software

El diseño de arquitecturas de software es un proceso altamente creativo que aún no ha sido estandarizado, por lo que las actividades llevadas a cabo para construir la arquitectura de un sistema son aquellas que los arquitectos involucrados consideran convenientes y pertinentes según el método de diseño que utilicen, su experiencia, conocimientos y habilidades personales. La reutilización es una práctica habitual dentro de dicha actividad. Sin embargo, no existen herramientas que asistan a los arquitectos para llevarla a cabo. En este trabajo se describe una herramienta de software construida con el objetivo de colaborar con los arquitectos de software en la recuperación de experiencias pasadas, propias y ajenas, para hacerlas accesibles de manera de que puedan ser reutilizadas durante el diseño de un nuevo sistema.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Reasoning and Reuse in Software Architecture Design : Practices in the Argentine Industry

Over the last years, software architecture design has gained significant importance in both, industrial and research areas due to its relevance in the software system development process. In this context, special attention has been given to the documentation of architects’ reasoning during an architectural design, highlighting the advantages and disadvantages of this activity. This work intends to present a view of architects’ practices in the Argentine industry regarding reasoning documentation and its subsequent use and access.Sociedad Argentina de Informática e Investigación Operativ