CP-violation and ππ\pi\pi-interaction in the radiative decays of KLK_L and KSK_S

The phases of terms of amplitude that arise from the $\pi\pi$ interaction are obtained by using a simple realistic model of $\pi\pi$ interaction via virtual $\rho$-meson, instead of the ChPT. It is shown that the standard ChPT approach cannot reproduce the contribution of the $\rho$-meson to the $\pi\pi$ interaction. It is shown that the interference between the terms of amplitude with different CP-parity appears only when the photon is polarized (linearly or circularly). Instead of measuring the linear polarization, the angular correlation between the $\pi^{+}\pi^{-}$ and $e^{+}e^{-}$ planes in $K_{S,L}\to\pi^{+}\pi^{-}e^{+}e^{-}$ decay can be studied.Comment: 6 pages, 7 figures, 1 table, LaTex; moriond.sty included; text corrected. Contribution to the XXXVIIth Rencontres de Moriond, "Electroweak interactions and unified theories", Les Arcs, France, 9-16 Mar 200

Vacuum polarization and plasma oscillations

We evidence the existence of plasma oscillations of electrons-positron pairs created by the vacuum polarization in an uniform electric field with E < Ec. Our general treatment, encompassing also the traditional, well studied case of E > Ec, shows the existence in both cases of a maximum Lorentz factor acquired by electrons and positrons and allows determination of the a maximal length of oscillation. We quantitatively estimate how plasma oscillations reduce the rate of pair creation and increase the time scale of the pair production. These results are particularly relevant in view of the experimental progress in approaching the field strengths E < Ec.Comment: to appear in Phys. Lett.

Tailored laser pulse chirp to maintain optimum radiation pressure acceleration of ions

Ion beams generated with ultra-intense lasers-plasma accelerators hold promises to provide compact and affordable beams of relativistic ions. One of the most efficient acceleration setups was demonstrated to be direct acceleration by the laser's radiation pressure. Due to plasma instabilities developing in the ultra-thin foils required for radiation pressure acceleration, however, it is challenging to maintain stable acceleration over long distances. Recent studies demonstrated, on the other hand, that specially tailored laser pulses can shorten the required acceleration distance suppressing the onset of plasma instabilities. Here we extend the concept of specific laser pulse shapes to the experimentally accessible parameter of a frequency chirp. We present a novel analysis of how a laser pulse chirp may be used to drive a foil target constantly maintaining optimal radiation pressure acceleration conditions for in dependence on the target's areal density and the laser's local field strength. Our results indicate that an appropriately frequency chirped laser pulse yields a significantly enhanced acceleration to higher energies and over longer distances suppressing the onset of plasma instabilities.Comment: 7 pages, 4 figure

Fundamental Physics and Relativistic Laboratory Astrophysics with Extreme Power Lasers

The prospects of using extreme relativistic laser-matter interactions for laboratory astrophysics are discussed. Laser-driven process simulation of matter dynamics at ultra-high energy density is proposed for the studies of astrophysical compact objects and the early universe.Comment: 12 pages, 15 figures. Invited talk at European Conference on Laboratory Astrophysics (ECLA), 26-30 September, 2011, Paris, France. Submitted to European Astronomical Society Publications Serie

Requirements and Tools for Variability Management

Explicit and software-supported Business Process Management has become the core infrastructure of any medium and large organization that has a need to be efficient and effective. The number of processes of a single organization can be very high, furthermore, they might be very similar, be in need of momentary change, or evolve frequently. If the ad-hoc adaptation and customization of processes is currently the dominant way, it clearly is not the best. In fact, providing tools for supporting the explicit management of variation in processes (due to customization or evolution needs) has a profound impact on the overall life-cycle of processes in organizations. Additionally, with the increasing adoption of Service-Oriented Architectures, the infrastructure to support automatic reconfiguration and adaptation of business process is solid. In this paper, after defining variability in business process management, we consider the requirements for explicit variation handling for (service based) business process systems. eGovernment serves as an illustrative example of reuse. In this case study, all local municipalities need to implement the same general legal process while adapting it to the local business practices and IT infrastructure needs. Finally, an evaluation of existing tools for explicit variability management is provided with respect to the requirements identified.