Nonlinear dynamics in superlattices driven by high frequency ac-fields

We investigate the dynamical processes taking place in nanodevices driven by high-frequency electromagnetic fields. We want to elucidate the role of different mechanisms that could lead to loss of quantum coherence. Our results show how the dephasing effects of disorder that destroy after some periods coherent oscillations, such as Rabi oscillations, can be overestimated if we do not consider the electron-electron interactions that can reduce dramatically the decoherence effects of the structural imperfections. Experimental conditions for the observation of the predicted effects are discussed.Comment: REVTEX (8 pages) and 4 figures (Postscript

Silicon strip prototypes for the Phase-II upgrade of the ATLAS tracker for the HL-LHC

This paper describes the integration structures for the silicon strips tracker of the ATLAS detector proposed for the Phase-II upgrade of the Large Hadron Collider (LHC), also referred to as High Luminosity LHC (HL-LHC). In this proposed detector Silicon strip sensors are arranged in highly modular structures, called `staves' and `petals'. This paper presents performance results from the latest prototype stave built at Berkeley. This new, double-sided prototype is composed of a specialized core structure, in which a shield-less bus tape is embedded in between carbon fiber lay-ups. A detailed description of the prototype and its electrical performance are discussed in detail.Comment: Presentation at the DPF 2013 Meeting of the American Physical Society Division of Particles and Fields, Santa Cruz, California, August 13-17, 201

Latest results on differential cross sections as a function of kinematic variables at the LHC and Tevatron

An overview of recent measurements of differential top quark pair ($t\bar{t}$) production cross sections is presented, including results in boosted topologies and results both at parton and particle level. The first measurements of differential single top quark t-channel production cross sections in proton-proton collisions are as well presented. The results are obtained using data collected with the ATLAS and CMS experiments in proton-proton collisions at centre-of-mass energies of 7 TeV and 8 TeV. References to the latest results by the Tevatron experiments are also given. The data are compared with several predictions from perturbative QCD calculations up to approximate next-to-next-to-leading-order precision (approx. NNLO).Comment: 5 pages, 4 figures, TOP2014 Conferenc

ttˉ{\rm t\bar{t}} cross section measurements in CMS

An overview of the most recent measurements of inclusive top quark pair production cross section is presented. The results are obtained using data collected with the CMS experiment in proton-proton collisions at centre-of-mass energies of 5.02, 7, 8 and 13 TeV. The data are compared with the predictions from perturbative QCD calculations at full NNLO+NNLL accuracy.Comment: 6 pages, 5 figures, TOP2016 conferenc

Consumer Credit in the European Union. ECRI Research Report No. 1, 1 February 2000

[From the Introduction]. Economic deregulation in many industrialised countries during the 1980s, the liberalisation of capital movements within the European Union (EU) in 1990, and the establishment of the single market for financial services have radically transformed the regulatory framework of European financial markets. One of the main objectives of the single market programme (1985) was the opening of national markets in order to create a European financial area with the free provision of financial services. Its implementation started in 1993 with the application of the second banking directive.1 In this context, monetary union is often seen as the accomplishment of the process of European financial integration. The elimination of exchange risk should indeed boost cross-border competition. The nature and speed of integration differ between wholesale and retail financial markets. Despite the pressure towards convergence stemming from monetary unification, national differences and market segmentation still characterise retail credit markets across EU member states. A first objective of this study is to compare the structure and developments of consumer credit markets in the EU

Note on scalars, perfect fluids, constrained field theories, and all that

The relation of a scalar field with a perfect fluid has generated some debate along the last few years. In this paper we argue that shift-invariant scalar fields can describe accurately the potential flow of an isentropic perfect fluid, but, in general, the identification is possible only for a finite period of time. After that period in the evolution the dynamics of the scalar field and the perfect fluid branch off. The Lagrangian density for the velocity-potential can be read directly from the expression relating the pressure with the Taub charge and the entropy per particle in the fluid, whereas the other quantities of interest can be obtained from the thermodynamic relations.Comment: 5 pages, 1 figure. Accepted for publication in Phys. Lett.

Investigation of split injection in a single cylinder optical diesel engine

SAE paper 2010-01-0605, Copyright © 2010 SAE International. This paper is posted on this site with permission from SAE International, and is for viewing only. Further use and distribution of this paper is not permitted without permission from SAE.Over the last decade, the diesel engine has made dramatic progress in its performance and market penetration. However, in order to meet future emissions legislations, Nitrogen Oxides (NOx) and particulate matters’ (PM) emissions will need to be reduced simultaneously. Nowadays researchers are focused on different combustion modes which can have a great potential for both low soot and low NOx. In order to achieve this, different injection strategies have been investigated. This study investigates the effects of split injection strategies with high levels of Exhaust Gas Recirculation (EGR) on combustion performance and emissions in a single cylinder direct injection optical diesel engine. The investigation is focused on the effects of injection timing of split injection strategies. A Ricardo Hydra single cylinder optical engine was used in which conventional experimental methods like cylinder pressure data, heat release analysis and exhaust emissions analysis were applied. Optical techniques like direct spray and combustion visualization were applied by means of a high speed imaging system with a copper vapor laser illumination system and a high-speed two-color system was applied to obtain in-cylinder diesel combustion temperature and soot measurements distributions

Slice theorem and orbit type stratification in infinite dimensions

We establish a general slice theorem for the action of a locally convex Lie group on a locally convex manifold, which generalizes the classical slice theorem of Palais to infinite dimensions. We discuss two important settings under which the assumptions of this theorem are fulfilled. First, using Gl\"ockner's inverse function theorem, we show that the linear action of a compact Lie group on a Fr\'echet space admits a slice. Second, using the Nash--Moser theorem, we establish a slice theorem for the tame action of a tame Fr\'echet Lie group on a tame Fr\'echet manifold. For this purpose, we develop the concept of a graded Riemannian metric, which allows the construction of a path-length metric compatible with the manifold topology and of a local addition. Finally, generalizing a classical result in finite dimensions, we prove that the existence of a slice implies that the decomposition of the manifold into orbit types of the group action is a stratification

Semiclassical theory of anisotropic transport at LaAlO3/SrTiO3 interfaces under in-plane magnetic field

The unconventional magnetotransport at the interface between transition-metal oxides $LaAlO_3$ (LAO) and $SrTiO_3$ (STO) is frequently related to mobile electrons interacting with localized magnetic moments. However nature and properties of magnetism at this interface are not well understood so far. In this paper, we focus on transport effects driven by spin-orbit coupling and intentionally neglect possible strong correlations. The electrical resistivity tensor is calculated as a function of the magnitude and orientation of an external magnetic field parallel to the interface. The semiclassical Boltzmann equation is solved numerically for the two-dimensional system of spin-orbit coupled electrons accelerated by an electric field and scattered by spatially-correlated impurities. At temperatures of a few Kelvin and densities such that the chemical potential crosses the second pair of spin-orbit split bands, we find a strongly anisotropic modulation of the (negative) magnetoresistance above 10 T, characterized by multiple maxima and minima away from the crystalline axes. Along with the drop of the magnetoresistance, an abrupt enhancement of the transverse resistivity occurs. The angular modulation of the latter considerably deviates from a (low-field) sinusoidal dependence to a (high-field) step-like behaviour. These peculiar features are the consequences of the anisotropy of both (intra-band and inter-band ) scattering-amplitudes in the Brillouin zone when the relevant energy scales in the system - chemical potential, spin-orbit interaction and Zeeman energy - are all comparable to each other. The theory provides good qualitative agreement with experimental data in the literature.Comment: 14 pages, 9 figures, 2 appendices. Extended version with discussion section widely revised, additional results for different parameters in Appendix B, theoretical model presented in details in Appendix A. To be published in Phys. Rev.

Bias-dependent D'yakonov-Perel' spin relaxation in bilayer graphene

We calculate the spin relaxation time of mobile electrons due to spin precession between random impurity scattering (D'yakonov-Perel' mechanism) in electrically gated bilayer graphene analytically and numerically. Due to the trigonal warping of the bandstructure, the spin relaxation time exhibits an interesting non-monotonic behavior as a function of both the Fermi energy and the interlayer bias potential. Our results are in good agreement with recent four-probe measurements of the spin relaxation time in bilayer graphene and indicate the possibility of an electrically-switched spin device.Comment: 9 pages, 3 figures, 1 tabl