Branching ratios and properties ofD-meson decays

Properties ofD mesons produced in the photo-production experiment NA 14/2 at CERN are reported. The following ratios of branching fractions were measured:

Association of Molybdenum Ionic Species with Alumina Surface

The adsorption isotherms at 25, 45, and 65 degrees C of molybdenum solutions of concentration ranges between 10(-3) and 3x10(-2) M(Mo) (pH 4-5) on different alumina samples are investigated. The analysis is conducted using a modified Frumkin isotherm which takes a more realistic account of the lateral interaction between adsorbed species and considers that the adsorption takes place on the most basic OH groups on the surface of alumina. The results are discussed in view of the difference in solutions speciation, and the changes in the pH of the remaining supernatant solutions. The solution temperature, PZC of the used aluminas, the configuration of the basic OH groups on their surface, and the pore structure have been shown to intervene effectively. Copyright 2000 Academic Press.     

A comparison of data reduction techniques for the aeroacoustic analysis of flow over a blunt flat plate

A large eddy simulation of flow over a forward-facing plate is performed and the resulting database analyzed with respect to sound radiation. Aeroacoustic analysis motivates an initial data compression comprising eduction of the zeroth-order spanwise Fourier mode. The space–time structure of this component of the flow is then analyzed using POD and DMD in order to probe both the energetics and dynamics of the sound-producing flow skeleton. Both data processing techniques educe flapping and shedding modes and identify a nonlinear interaction between the two. POD shows the flapping mode to be energetically unimportant, while DMD highlights its dynamic importance. The difference mode—vortex shedding modulated by flapping of the separation bubble—is found to be the most acoustically important feature of the flow.     

Tailored nearfield Green's functions for arbitrary geometries

An iterative technique, taken from the field of optics, is used to obtain tailored Green's functions suitable for the evaluation, in the nearfield, of pressure fluctuations generated by turbulent flow in the vicinity of solid boundaries. Comparisons are made with the analytical solution for the solid sphere, and with results obtained using conventional boundary element method (BEM) for the case of a thick semi-infinite plate. A divergence issue in the case of the solid sphere is resolved by the introduction of a relaxation factor. The performance of the iterative approach is found to be comparable to that of conventional BEM, except at irregular frequencies, where the bandwidth of the error is slightly larger than that of the conventional BEM. The main advantage of the iterative approach is a significantly reduced computational cost, which allows for higher surface mesh densities and a broader useful frequency range.     

List Coloring with a Bounded Palette

Král' and Sgall (J Graph Theory 49(3) (2005), 177–186) introduced a refinement of list coloring where every color list must be subset to one predetermined palette of colors. We call this ‐choosability when the palette is of size at most ? and the lists must be of size at least k . They showed that, for any integer , there is an integer , satisfying as , such that, if a graph is ‐choosable, then it is C‐choosable, and asked if C is required to be exponential in k . We demonstrate it must satisfy . For an integer , if is the least integer such that a graph is ‐choosable if it is ‐choosable, then we more generally supply a lower bound on , one that is super‐polynomial in k if , by relation to an extremal set theoretic property. By the use of containers, we also give upper bounds on that improve on earlier bounds if .     

The role of ΔK = ±3 transitions in collision-broadened NH3

The half-widths of ammonia lines collision-broadened by H₂, N₂ and CO₂ have been calculated for microwave and far-i.r. spectra. The R^-7 dispersion potential, which induced ΔK = ±3 transitions, was included in the calculations. A comparison is then made with available experimental data.     

Rovibrational inelastic scattering using adiabatic basis functions. Study of the 4 He + p-H2 collision

The exponential perturbed stationary state approximation is tested for rovibrational inelastic scattering. It appears as a fairly good approach in the low-energy range and would be promising in the whole energy scale by means of minor improvements.     

Memory effects in speed-changing collisions and their consequences for spectral line shape

The kinetic model accounting for speed-memory effects on the spectral line shape proposed in I [D. Robert, L. Bonamy, Eur. Phys. J. D 2, 245 (1998)] is extended for any density range, within the binary collision framework. The additional Doppler contribution requires to consider the 3D velocity-memory function instead of the 1D speed one, with distinct treatments for the velocity-orientation and velocity-modulus memory mechanisms. Both the collisional confinement narrowing of the Doppler distribution and the radiator speed-dependence of the collisional broadening and shifting parameters are thus conveniently taken into account. In the high density regime, this model leads to the same results as in I. At lower densities, it generalizes the very well-known hard and soft collision models for the Dicke narrowing of the Doppler distribution, but it also includes the second source of inhomogeneity tied to the speed-dependent collisional parameters and, concomitantly, the speed class exchanges. Numerical applications to H₂-N₂ and H₂-Ar gaseous mixtures are in close agreement with experiments. This allows one to clearly analyze the specific role of speed and velocity memory effects on the line profile.Received: 18 June 2004, Published online: 3 November 2004PACS: 34.10. + x General theories and models of atomic and molecular collisions and interactions (including statistical theories, transition state, stochastic and trajectory models, etc.) - 33.70.Jg Line and band widths, shapes, and shifts     

Semiclassical calculations of collision line broadening in Raman spectra of N2 and CO mixtures

We present a detailed theoretical study of pressure-broadened Raman line shapes in binary mixtures of nitrogen and carbon monoxide. The semiclassical Robert-Bonamy theory was used to calculate self-broadened Q-branch linewidths of N(2) and CO, and Lennard-Jones (LJ) potential energy surface parameters were fixed by comparing our results with extensive experimental linewidth data. For the case of N(2), the ab initio PES8 potential energy surface was investigated, however, the anisotropic repulsive part had to be reduced to ensure a good agreement with experimental linewidths. The agreement between calculations and experiments was remarkably good, both for self-broadened N(2) and CO Q-branch linewidths. Yet, our calculations were not able to predict the experimentally observed difference between Q- and S-branch linewidths of self-broadened N(2). The central results of this work are the Q-branch linewidths of N(2)-CO and CO-N(2), which have been calculated through an extrapolation of the parameters of the potential energy surfaces used for self-broadened linewidths by common combination rules.