Handbook of Higher Twist Distribution Amplitudes of Vector Mesons in QCD

We give a summary of existing results on higher twist distribution amplitudes of vector mesons in QCD. Special attention is payed to meson mass corrections which turn out to be large. A ``shopping list'' is presented of most important nonperturbative parameters which enter distribution amplitudes.Comment: Talk presented by V.M. Braun at 3rd workshop ``Continuous Advances in QCD'', Minneapolis, MN, USA, April 16--19, 1998; 17 pages, 2 figures, requires sprocl.sty (included

The stress transmission universality classes of periodic granular arrays

The transmission of stress is analysed for static periodic arrays of rigid grains, with perfect and zero friction. For minimal coordination number (which is sensitive to friction, sphericity and dimensionality), the stress distribution is soluble without reference to the corresponding displacement fields. In non-degenerate cases, the constitutive equations are found to be simple linear in the stress components. The corresponding coefficients depend crucially upon geometrical disorder of the grain contacts

The Bs→KB_{s}\to K Form Factor in The Whole Kinematically Accessible Range

A systematic analysis is presented of the $B_{s}\to K$ form factor $f(q^{2})$ in the whole range of momentum transfer $q^{2}$, which would be useful to analyzing the future data on $B_{s}\to K$ decays and extracting $| V_{ub}|$. With a modified QCD light cone sum rule (LCSR) approach, in which the contributions cancel out from the twist 3 wavefunctions of $K$ meson, we investigate in detail the behavior of $f(q^{2})$ at small and intermediate $q^{2}$ and the nonperturbative quantity $f_{B^{\ast}}g_{B^{\ast}B_{s}K}$ $(f_{B^{\ast}}$ is the decay constant of $B^{\ast}$ meson and $g_{B^{\ast}B_{s}K}$ the $B^{\ast}B_{s}K$ strong coupling), whose numerical result is used to study $q^{2}$ dependence of $f(q^{2})$ at large $q^{2}$ in the single pole approximation. Based on these findings, a form factor model from the best fit is formulated, which applies to the calculation on $f(q^{2})$ in the whole kinematically accessible range. Also, a comparison is made with the standard LCSR predictions.Comment: 11 pages, Latex, 1 eps figure, Final version to appear in Phys.Rev.

Isostaticity in two dimensional pile of rigid disks

We study the static structure of piles made of polydisperse disks in the rigid limit with and without friction using molecular dynamic simulations for various elasticities of the disks and pile preparation procedures. The coordination numbers are calculated to examine the isostaticity of the pile structure. For the frictionless pile, it is demonstrated that the coordination number converges to 4 in the rigid limit, which implies that the structure of rigid disk pile is isostatic. On the other hand, for the frictional case with the infinite friction constant, the coordination number depends on the preparation procedure of the pile, but we find that the structure becomes very close to isostatic with the coordination number close to 3 in the rigid limit when the pile is formed through the process that tends to make a pile of random configuration.Comment: 3 pages, 3 figures, Submitted to J. Phys. Soc. Jp

Lattice deformations at martensite-martensite interfaces in Ni-Al

The atomic configurations at macrotwin interfaces between microtwinned martensite plates in $Ni_{65}Al_{35}$ material are investigated using high resolution transmission electron microscopy (HRTEM). The observed structures are interpreted in view of possible formation mechanisms of these interfaces. A distinction is made between cases in which the microtwins, originating from mutually perpendicular \{110\} austenite planes, enclose a final angle larger or smaller than $90^{\circ}$, measured over the boundary. Two different configurations, one with crossing microtwins and the other with ending microtwins producing a step configuration are described. The latter is related with the existence of microtwin sequences with changing variant widths. Although both features appear irrespective of the material’s preparation technique, rapid solidification seems to prefer the step configuration. Depending on the actual case, tapering, bending and tip splitting of the small microtwin variants is observed. Sever lattice deformations and reorientations occur in a region of 5 – 10 nm around the interface while sequences of single plane ledges gradually bending the microtwins are found up to 50 nm away form the interface. These structures and deformations are interpreted in view of the need to accommodate any remaining stresses

Poisson transition rates from time-domain measurements with finite bandwidth

In time-domain measurements of a Poisson two-level system, the observed transition rates are always smaller than those of the actual system, a general consequence of finite measurement bandwidth in an experiment. This underestimation of the rates is significant even when the measurement and detection apparatus is ten times faster than the process under study. We derive here a quantitative form for this correction using a straightforward state-transition model that includes the detection apparatus, and provide a method for determining a system's actual transition rates from bandwidth-limited measurements. We support our results with computer simulations and experimental data from time-domain measurements of quasiparticle tunneling in a single-Cooper-pair transistor.Comment: 4 pages, 5 figure

U.S. Agriculture, 1960-96 A Multilateral Comparison of Total Factor Productivity

This study provides estimates of the growth and relative levels of agricultural productivity for the 48 contiguous States for the period 1960 to 1996. For the full 1960-96 period, every State exhibits a positive and generally substantial average annual rate of productivity growth. There is considerable variance, however. The wide disparity in growth rates resulted in substantial changes in the ranking order of States by productivity. For each year, we calculate the coefficient of variation of productivity levels. We use these coefficients to show that the range of levels of productivity has narrowed over time, although the pattern of convergence was far from uniform. The fact that in some States, productivity grew faster than others and yet the cross-section dispersion decreased, implies that the States whose productivity grew most rapidly were those with lower initial levels of productivity. This result is consistent with Gerschenkron's notion of the advantage of relative backwardness. The States that were particularly far behind the productivity leaders had the most to gain from the diffusion of technical knowledge and proceeded to grow most rapidly. We also observe a positive relation between capital accumulation and productivity growth, implying embodiment of technology in capital.production accounts, multilateral index numbers, total factor productivity, Productivity Analysis,