Experimental study of the time-dependent rate of K → πππ

The time-dependence of the decay rate of initially pure K⁰ into the final state (π⁺π⁻π⁰) has been studied in search for the decay k_S⁰→π⁺π⁻π⁰. No evidence is found in a sample of 384 observed events. The ratio of the CP -violating K_S⁰ amplitude and the K_L⁰ amplitude is η₊₋₀ = (0.13_−0.20^+0.17) + i(0.17_−0.26^+0.27); the ratio of the CP-conserving K_S⁰ amplitude and the K_L⁰ amplitude is < 0.4. The energy dependence of the K⁰→π⁺π⁻π⁰ matrix element is found to be a₊₋₀ = −0.31 ± 0.03.     

Preface

Preface

Preface     

Evaluation of the elastic and plastic theories as components of a general doctrine of analysis and design of metal structures

Summary A general method is developed to evaluate the nonstationary response of a linear damped system subjected to a random excitation which is represented as the product of a modulating deterministic function and a white noise process. An approximate solution method is presented first by means of a step-by-step procedure; then this method is shown to be able to generate a differential equation for the time variation of the mean square response. Stability and accuracy of the step-by-step procedure are discussed in detail, and compared with other methods. Extension to multidegree of freedom and nonlinear systems are discussed.

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Sommario Viene sviluppato un metodo per il calcolo del valore quadratico medio di un sistema lineare eccitato da forzanti aleatorie localmente stazionarie con densità spettrale di potenza uniforme. Viene dapprima presentata una procedura di tipo passo-passo; con passaggio al limite si ottiene un'equazione differenziale che definisce il modo con cui varia il valore quadratico medio al variare del tempo. Viene discussa in dettaglio altresi l'accuratezza e la stabilità della procedura al passo. Infine si estende il metodo ai sistemi a più gradi di libertà e a quelli non lineari.

     

Experimental results on diffractive one-pion production at the CERN ISR

New experimental results are reported on diffractive dissociation of protons into (nπ⁺) in proton-proton collisions at a centre-of-mass energy of $\text{s}\text{= 45}\text{GeV}$. The data were obtained using the Split-Field-Magnet detector at the CERN Intersecting Storage Rings. We have searched for resonance contributions and found peaks at mass values of 1.5 GeV, 1.65 GeV, and 2.1 GeV. A dip in $\text{d}\text{σ}\text{d}\text{t}$ is observed at low t and low mass; it is most pronounced for events with neutrons emitted at 90° in the Gottfried-Jackson frame. The correlation between mass and slope depends strongly on θ_J. The cross section of the channel pp → pnπ⁺ is 400 ± 110 μb at $\text{s}\text{= 45}\text{GeV}$, giving an energy dependence of s^?0.30±0.07 for isospin exchange zero in this channel.     

A study of the charge-exchange reaction pp → nΔ++(1232) at ISR energies

We report on a study of the charge-exchange reaction pp → nΔ⁺⁺(1232) at the CERN intersecting storage rings (ISR) in the energy range √s = 23 to 53 GeV. From our analysis of the energy dependence of the total cross-section, of the differential cross-section dσ/dt and of the decay angular distributions we find evidence that pion exchange is dominant up to √s = 23 GeV and that (?+A₂) exchange dominates the reaction for √s ? 30 GeV, as described by simple Regge-pole models.     

Buckling behaviour of imperfect elastic and linearly viscoelastic structures

In a previous paper, the author has shown that the behaviour of imperfect elastic structures subjected to buckling forces could be predicted on the basis of the eigenvalues and eigenmodes. After a brief recall of these properties, it is first shown—in Appendix—that they extend to cases of spatial buckling like the buckling of flexure and torsion. Then, it is shown that the correspondence principle valid in first-order behaviour of linearly viscoelastic structures can be extended in full generality—by the use of Laplace transformation—to buckling problems, whatever be the constitutive equations of the material.Finally, several examples of eulerian buckling or flexural-torsional buckling of a bar and of buckling of a plate, are treated in detail.     

Approximation algorithms for deterministic continuous-review inventory lot-sizing problems with time-varying demand

This work deals with the continuous time lot-sizing inventory problem when demand and costs are time-dependent. We adapt a cost balancing technique developed for the periodic-review version of our problem to the continuous-review framework. We prove that the solution obtained costs at most twice the cost of an optimal solution. We study the numerical complexity of the algorithm and generalize the policy to several important extensions while preserving its performance guarantee of two. Finally, we propose a modified version of our algorithm for the lot-sizing model with some restricted settings that improves the worst-case bound.     

Production of pseudoscalar mesons in 300 GeV central π+ N collisions

The exculsive production of π⁰, η, and η′ mesons in π⁺ N central collisions has been studied with 300 GeV incident pions. The experiment has been performed at the CERN SPS. The gammas from decaying mesons were detected in the hodoscope multiphoton spectrometer GAMS-4000. The measured differential cross sections show a plateau in the longitudinal momentum interval 0.1F<0.3.     

Experimental results on large angle elastic pp scattering at the CERN ISR

New experimental results are presented on proton-proton elastic scattering at centre-of-mass energies $\text{s}\text{=23}\text{GeV}$ and $\text{s}\text{=62}\text{GeV}$. The data are obtained using the Split Field Magnet detector at the CERN Intersecting Storage Rings. The absolute differential cross-sections show an energy-dependent behaviour. The position of the diffraction minimum changes from t=(?1.44±0.02)GeV² at 23 GeV to (?1.26±0.03)GeV² at 62 GeV. The cross-section at the second maximum is increasing with $\text{s}$. The connection of these observations with the hypothesis of “geometrical scaling” is discussed.