Semiclassical Diagonalization of Quantum Hamiltonian and Equations of Motion with Berry Phase Corrections

It has been recently found that the equations of motion of several semiclassical systems must take into account terms arising from Berry phases contributions. Those terms are responsible for the spin Hall effect in semiconductor as well as the Magnus effect of light propagating in inhomogeneous media. Intensive ongoing research on this subject seems to indicate that a broad class of quantum systems may be affected by Berry phase terms. It is therefore important to find a general procedure allowing for the determination of semiclassical Hamiltonian with Berry Phase corrections. This article presents a general diagonalization method at order $\hbar$ for a large class of quantum Hamiltonians directly inducing Berry phase corrections. As a consequence, Berry phase terms on both coordinates and momentum operators naturally arise during the diagonalization procedure. This leads to new equations of motion for a wide class of semiclassical system. As physical applications we consider here a Dirac particle in an electromagnetic or static gravitational field, and the propagation of a Bloch electrons in an external electromagnetic field.Comment: 15 page

Berry Phase Effects in the dynamics of Dirac Electrons in Doubly Special Relativity Framework

We consider the Doubly Special Relativity (DSR) generalization of Dirac equation in an external potential in the Magueijo-Smolin base. The particles obey a modified energy-momentum dispersion relation. The semiclassical diagonalization of the Dirac Hamiltonian reveals the intrinsic Berry phase effects in the particle dynamics

CLIC Detector Main Solenoid Design & Status Report

The magnet system for the CLIC Detector concepts is composed of the central solenoid in combination with the two forward anti-solenoids and the ancillary systems necessary for their operation, including the so-called push-pull scenario, allowing the quick exchange of the two detectors on the beam line. An overview of the design parameters of the detector main solenoids is presented hereafter.Comment: LCWS2011, Granada, Spai

Nouvelles études sur la provenance géographique des blocs utilisés pour la construction de monuments mégalithiques dans le département du Puy-de-Dôme

International audienceIn a previous article, we described the results of our research work on the source of the boulders that were used for the construction of certain megalithic monuments in the département of Puy de Dôme, mostly in the Limagne area. This study has led us to the conclusion that the stones from which the megaliths were made were not taken from the place where the monument was erected. The boulders, some weighing up to 10 tons, were dragged for distances of about 15 km. This allowed us to point out two facts which had already been emphasized by various authors studying other monuments in different areas. First of all, it is quite clear that for the builders, the choice of the construction site was not dictated by geological considerations but was made according to other criteria. Second, choosing the right place to build the monument was an essential part of the process. For this article, we have studied 14 dolmens and 8 menhirs from different areas of the département of Puy-de-Dôme. This study shows that the sites that were selected for the construction appear to have been the natural limits of the landscape and/or clearly visible places overlooking a wide territory. Indeed, Neolithic populations deliberately built monuments that were meant to be seen, and they erected them in very distinctive locations. That is why it is quite natural to suggest that those impressive monuments must have been considered as landmarks for sedentary or semi-sedentary populations. On the other hand, the transport of the boulders, a colossal task, provides evidence of the high degree of engineering ability and social organisation possesed by Neolithic communities. In order to give more susbtance and better support to these assumptions, we decided to extend our study to the other monuments of the département. In the course of this work, we have made new discoveries and have re-examined our interpretation of certain megalithic monuments. The results of this research work will be found in the list that follows. This latest stage of our research work on the megalithic monuments of the Puy de Dôme has brought us to the same conclusion that we had reached in our previous study. In most cases, the boulders from which the monuments were made were not found on the sites on which they were built. Neolithic builders may sometimes have found satisfactory material on the chosen spot and have used it, but most of the time, owing to a lack of local material, they were compelled to carry the stones distances ranging from a dozen metres up to 100 metres. When choosing the location for the construction of a monument, therefore, they had in mind other criteria than merely the local supply of suitable building material. We should also note that they looked for sites from which they had an excellent view over the surrounding area: thus, they were sure that the monuments would be clearly visible from far. And yet they avoided the highest uplands. The favourite location was undoubtedly the edge of a plateau. Unfortunately, so little is known about the Neolithic period in this region that we cannot establish possible links between megalithic monuments and settlements. It should be noted, however, that a number of polished stone axes have been found at megalithic sites (Surmely, 2001). The foregoing allows us to repeat again the following statement: megalithic monuments were used as landmarks by highly organised human groups.Dans un précédent article (Surmely et al. 1996), nous avions présenté le résultat de nos recherches sur la provenance des blocs utilisés pour la construction de certains monuments mégalithiques du département du Puy-de-Dôme, essentiellement dans le secteur de la Limagne, et du département du Cantal. Cette étude, basée sur une analyse pétrographique détaillée des constituants des monuments et du contexte, avait permis de mettre en évidence le fait que les pierres constituant les mégalithes n'avaient pas été prises à l'endroit où le monument avait été érigé. Le transport de ces blocs, pesant parfois plus de dix tonnes, atteignait des distances de près de 15 km. Pour étayer notre démonstration et lui donner plus de force, nous avons choisi d'étendre notre étude aux autres monuments du département du Puy-de-Dôme, ce qui nous a amené, ce faisant, à réaliser des découvertes et à revoir l'interprétation de certains mégalithes. C'est le résultat de ces recherches qui est présenté ici, de façon très résumée. L'intégralité de nos observations figure dans un autre article (Surmely et Goër, sous presse). Il est à noter que la majeure partie des monuments n'est pas datée de façon précise, faute de recherches récentes

Exocomets in the circumstellar gas disk of HD 172555

The source HD172555 is a young A7V star surrounded by a debris disk with a gaseous component. Here, we present the detection of variable absorption features detected simultaneously in the Ca II K and H doublet lines (at 3,933 and 3,968 Angstrom). We identified the presence of these absorption signatures at four different epochs in the 129 HARPS high-resolution spectra gathered between 2004 and 2011. These transient absorption features are most likely due to Falling Evaporating Bodies (FEBs, or exocomets) that produce absorbing gas observed transiting in front of the central star. We also detect a stable Ca II absorption component at the star's radial velocity. With no corresponding detection in the Na I line, the resulting very low upper limit for the NaI/CaII ratio suggests that this absorption is due to circumstellar gas.Comment: Accepted for publication in Astronomy&Astrophysics Letter