NNLO massive corrections to Bhabha scattering and theoretical precision of BabaYaga@NLO

We provide an exact calculation of next-to-next-to-leading order (NNLO) massive corrections to Bhabha scattering in QED, relevant for precision luminosity monitoring at meson factories. Using realistic reference event selections, exact numerical results for leptonic and hadronic corrections are given and compared with the corresponding approximate predictions of the event generator BabaYaga@NLO. It is shown that the NNLO massive corrections are necessary for luminosity measurements with per mille precision. At the same time they are found to be well accounted for in the generator at an accuracy level below the one per mille. An update of the total theoretical precision of BabaYaga@NLO is presented and possible directions for a further error reduction are sketched.Comment: 5 pages, 3 tables, contrib. to proceedings of International Workshop on e+e- collisions: from Phi to Psi, PHIPSI11, BINP, Novosibirsk, Russia, September 19-22, 201

Automated Reconstruction of Particle Cascades in High Energy Physics Experiments

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.Comment: 8 pages, 2 figures. Submitted to Computational Science & Discover

A Development Environment for Visual Physics Analysis

The Visual Physics Analysis (VISPA) project integrates different aspects of physics analyses into a graphical development environment. It addresses the typical development cycle of (re-)designing, executing and verifying an analysis. The project provides an extendable plug-in mechanism and includes plug-ins for designing the analysis flow, for running the analysis on batch systems, and for browsing the data content. The corresponding plug-ins are based on an object-oriented toolkit for modular data analysis. We introduce the main concepts of the project, describe the technical realization and demonstrate the functionality in example applications

EU External Relations: Exclusive Competence Revisited

This Article will focus on the question of exclusive competence in the field of EU external relations, especially in the light of recent developments. After a brief discussion on the origins and development of exclusive competence, a distinction will be made between common commercial policy, which has traditionally been the most important area of an explicit “a priori” exclusive competence, and what is often called an implicit exclusive competence, which, as it is today based on some general criteria enshrined in TFEU Article 3(2), may be called “supervening” exclusive competence. With regard to both categories, the main focus will be on recent developments, notably the impact of the Treaty of Lisbon, which introduced the TFEU and its Articles 2 and 3, as well as the case law of the European Court of Justice (“ECJ” or the “Court”) following the entry into force of the Treaty of Lisbon, on December 1, 2009

Gauge-independent MS‾\overline{MS} renormalization in the 2HDM

We present a consistent renormalization scheme for the CP-conserving Two-Higgs-Doublet Model based on $\overline{MS}$ renormalization of the mixing angles and the soft-$Z_2$-symmetry-breaking scale $M_{sb}$ in the Higgs sector. This scheme requires to treat tadpoles fully consistently in all steps of the calculation in order to provide gauge-independent $S$-matrix elements. We show how bare physical parameters have to be defined and verify the gauge independence of physical quantities by explicit calculations in a general $R_{\xi}$-gauge. The procedure is straightforward and applicable to other models with extended Higgs sectors. In contrast to the proposed scheme, the $\overline{MS}$ renormalization of the mixing angles combined with popular on-shell renormalization schemes gives rise to gauge-dependent results already at the one-loop level. We present explicit results for electroweak NLO corrections to selected processes in the appropriately renormalized Two-Higgs-Doublet Model and in particular discuss their scale dependence.Comment: 52 pages, PDFLaTeX, PDF figures, JHEP version with Eq. (5.23) correcte

Visual Physics Analysis (VISPA) - Concepts and First Applications

VISPA is a novel development environment for high energy physics analyses, based on a combination of graphical and textual steering. The primary aim of VISPA is to support physicists in prototyping, performing, and verifying a data analysis of any complexity. We present example screenshots, and describe the underlying software concepts.Comment: Parallel talk at ICHEP08, Philadelphia, USA, July 2008. 4 pages, 2 figure

Gamma-ray signatures of cosmic ray acceleration, propagation, and confinement in the era of CTA

Galactic cosmic rays are commonly believed to be accelerated at supernova remnants via diffusive shock acceleration. Despite the popularity of this idea, a conclusive proof for its validity is still missing. Gamma-ray astronomy provides us with a powerful tool to tackle this problem, because gamma rays are produced during cosmic ray interactions with the ambient gas. The detection of gamma rays from several supernova remnants is encouraging, but still does not constitute a proof of the scenario, the main problem being the difficulty in disentangling the hadronic and leptonic contributions to the emission. Once released by their sources, cosmic rays diffuse in the interstellar medium, and finally escape from the Galaxy. The diffuse gamma-ray emission from the Galactic disk, as well as the gamma-ray emission detected from a few galaxies is largely due to the interactions of cosmic rays in the interstellar medium. On much larger scales, cosmic rays are also expected to permeate the intracluster medium, since they can be confined and accumulated within clusters of galaxies for cosmological times. Thus, the detection of gamma rays from clusters of galaxies, or even upper limits on their emission, will allow us to constrain the cosmic ray output of the sources they contain, such as normal galaxies, AGNs, and cosmological shocks. In this paper, we describe the impact that the Cherenkov Telescope Array, a future ground-based facility for very-high energy gamma-ray astronomy, is expected to have in this field of research.Comment: accepted to Astroparticle Physics, special issue on Physics with the Cherenkov Telescope Arra

Proyecto "Satélite Universitario" de la Universidad Nacional de La Plata: viabilidad, áreas de interés y misiones consideradas

El proyecto Satélite Universitario, encabezado por el Centro Tecnológico Aeroespacial (CTA), tiene el objetivo de diseñar, construir, ensayar y operar el primer satélite de la Universidad Nacional de La Plata. Habiendo participado en gran parte de las misiones satelitales argentinas a través del Grupo de Ensayos Mecánicos Aplicados (GEMA), el CTA tiene más de 20 años de experiencia en el área espacial y una infraestructura apta para la construcción y ensayo de satélites. Con la creación de la carrera de Ingeniería Aeroespacial, este proyecto busca darles a los estudiantes la oportunidad de participar en el proceso de desarrollo de sistemas espaciales desde las fases iniciales hasta el lanzamiento, operación y fin de vida. En este trabajo se presentará un resumen del estudio de viabilidad desde las perspectivas de la infraestructura, el desarrollo tecnológico y la experiencia de los profesionales involucrados. Además, se detallan las áreas de interés captadas en la primera convocatoria y las misiones que se consideraron para este primer satélite, como punto de posible colaboración con otras universidades e instituciones.Centro Tecnológico Aeroespacia

Mini-review on Monte Carlo programs for Bhabha scattering

We review the status of Monte Carlo generators presently used for simulations of the large-angle Bhabha process at electron-positron colliders of moderately high energy (flavour factories), operating at centre-of-mass energies between about 1 GeV and 10 GeV. It is shown how the theoretical accuracy reached by present Bhabha programs for physics at flavour factories is at the level of 0.1% and, therefore, comparable with that reached about a decade ago for luminosity monitoring through small-angle Bhabha scattering at LEP.Comment: Contribution to the Proceedings of the 9th DESY workshop on "Loops and Legs in Quantum Field Theory", Sondershausen, April 200

On relativization of the Sommerfeld-Gamow-Sakharov factor

The Sommerfeld-Gamow-Sakharov factor is considered for the general case of arbitrary masses and energies. It is shown that the scalar triangular one-loop diagram gives the Coulomb singularity in radiative corrections at the threshold. The singular part of the correction is factorized at the complete Born cross section regardless of its partial wave decomposition. Different approaches to generalize the factor are discussed.Comment: 9 pages, 4 figures; references and discussion are extende