Mechanisms of Auger-induced chemistry derived from wave packet dynamics

To understand how core ionization and subsequent Auger decay lead to bond breaking in large systems, we simulate the wave packet dynamics of electrons in the hydrogenated diamond nanoparticle C_(197)H_(112). We find that surface core ionizations cause emission of carbon fragments and protons through a direct Auger mechanism, whereas deeper core ionizations cause hydrides to be emitted from the surface via remote heating, consistent with results from photon-stimulated desorption experiments [Hoffman A, Laikhtman A, (2006) J Phys Condens Mater 18:S1517–S1546]. This demonstrates that it is feasible to study the chemistry of highly excited large-scale systems using simulation and analysis tools comparable in simplicity to those used for classical molecular dynamics

Dirac-Schr\"odinger equation for quark-antiquark bound states and derivation of its interaction kerne

The four-dimensional Dirac-Schr\"odinger equation satisfied by quark-antiquark bound states is derived from Quantum Chromodynamics. Different from the Bethe-Salpeter equation, the equation derived is a kind of first-order differential equations of Schr\"odinger-type in the position space. Especially, the interaction kernel in the equation is given by two different closed expressions. One expression which contains only a few types of Green's functions is derived with the aid of the equations of motion satisfied by some kinds of Green's functions. Another expression which is represented in terms of the quark, antiquark and gluon propagators and some kinds of proper vertices is derived by means of the technique of irreducible decomposition of Green's functions. The kernel derived not only can easily be calculated by the perturbation method, but also provides a suitable basis for nonperturbative investigations. Furthermore, it is shown that the four-dimensinal Dirac-Schr\"odinger equation and its kernel can directly be reduced to rigorous three-dimensional forms in the equal-time Lorentz frame and the Dirac-Schr\"odinger equation can be reduced to an equivalent Pauli-Schr\"odinger equation which is represented in the Pauli spinor space. To show the applicability of the closed expressions derived and to demonstrate the equivalence between the two different expressions of the kernel, the t-channel and s-channel one gluon exchange kernels are chosen as an example to show how they are derived from the closed expressions. In addition, the connection of the Dirac-Schr\"odinger equation with the Bethe-Salpeter equation is discussed

Renormalization of the Sigma-Omega model within the framework of U(1) gauge symmetry

It is shown that the Sigma-Omega model which is widely used in the study of nuclear relativistic many-body problem can exactly be treated as an Abelian massive gauge field theory. The quantization of this theory can perfectly be performed by means of the general methods described in the quantum gauge field theory. Especially, the local U(1) gauge symmetry of the theory leads to a series of Ward-Takahashi identities satisfied by Green's functions and proper vertices. These identities form an uniquely correct basis for the renormalization of the theory. The renormalization is carried out in the mass-dependent momentum space subtraction scheme and by the renormalization group approach. With the aid of the renormalization boundary conditions, the solutions to the renormalization group equations are given in definite expressions without any ambiguity and renormalized S-matrix elememts are exactly formulated in forms as given in a series of tree diagrams provided that the physical parameters are replaced by the running ones. As an illustration of the renormalization procedure, the one-loop renormalization is concretely carried out and the results are given in rigorous forms which are suitable in the whole energy region. The effect of the one-loop renormalization is examined by the two-nucleon elastic scattering.Comment: 32 pages, 17 figure

The effect of tool fixturing quality on the design of condition monitoring systems for detecting tool conditions

Condition monitoring systems of machining processes are essential technology for improving productivity and automation. Tool wear monitoring of cutting tools is one of the important applications in this area. In this paper, the effect of collet fixturing quality on the design of condition monitoring systems to detect tool wear is discussed. The paper investigates the difference in the system's behaviour and the changes in the condition monitoring system when the cutting tool is not rigidly fastened to the collet. A group of sensors, namely acoustic emission, force, strain, vibration and sound, are used to design the condition monitoring system. Automated Sensor and Signal Processing Selection (ASPS) approach1 is implemented to address the effect of the tool holding device (collet) on the monitoring system and the most sensitive sensors and signal processing method to detect tool wear. The results prove that the change in the fixturing quality could have significant effect on the design of the condition monitoring system and the behaviour of the system

Parity-Violating Electron Scattering as a Probe of Supersymmetry

We compute the one-loop supersymmetric (SUSY) contributions to the weak charges of the electron ($Q_W^e$) and proton ($Q_W^p$) using the Minimal Supersymmetric Standard Model (MSSM). These $q^2=0$ vector couplings of the $Z^0$-boson to fermions will be determined in two fixed-target, parity-violating electron scattering experiments. The SUSY loop contributions to $Q_W^p$ and $Q_W^e$ can be substantial, leading to several percent corrections to the Standard Model values for these quantities. We show that the relative signs of the SUSY loop effects on $Q_W^e$ and $Q_W^p$ are correlated and positive over nearly all of the MSSM parameter space, whereas inclusion of R-parity nonconserving interactions can lead to opposite sign relative shifts in the weak charges. Thus, a comparison of $Q_W^p$ and $Q_W^e$ measurements could help distinguish between different SUSY scenarios.Comment: 4 pages, 2 figure

An innovative approach for energy generation from waves

Sustainable energy generation is becoming increasingly important due to the expected limitations in current energy resources and to reduce pollution. Wave energy generation has seen significant development in recent years. This paper describes an innovative system for generating energy from wave power. A complete description of the system is presented including the general concept, configurations, mechanical design, electrical system, simulation techniques and expected power output of the system. The results from the hydraulic linear wave simulator, using a real wave profiles captured at a location in the UK using an ultrasound system, it was seen that a ±0.8 m wave at 10 s time period, produced a conditioned power output of approximately 22 kW at optimum load conditions for the tested 3-phase 44 kW permanent magnet generator type STK500. The results indicate that this new technology could provide an efficient and low cost method of generating electricity from waves

Probing Supersymmetry with Neutral Current Scattering Experiments

We compute the supersymmetric contributions to the weak charges of the electron and proton in the framework of Minimal Supersymmetric Standard Model. We also consider the ratio of neutral current to charged current cross sections, R_nu and R_nubar at nu (nubar)-nucleus deep inelastic scattering, and compare the supersymmetric corrections with the deviations of these quantities from the Standard Model predictions implied by the recent NuTeV measurement.Comment: 4 pages, contribution to the proceedings of CIPANP 2003 (May, 2003), New York Cit