Λ, Λ production in e+e− annihilation at 33 GeV centre of mass energy

Performing a PWA of the π^?π^?π⁺ system over the ^?tp/p range 0.2 to 0.4 GeV² we find evidence for a J^P = 0^? ,J^G=1^? meson of mass 1342 ± 20 MeV and width 220 ±70 MeV decaying into ?π. This state is produced by natural parity exchange with a slope similar to that of elastic scattering. It can be interpreted as a radial excitation of the π meson (π′).     

A measurement of σtot(e+e− → hadrons) for cm energies between 12.0 and 36.7 GeV

The ration R = σ(e⁺e^? → hadrons)σ_μμ was measured between 12.0 and 36.7 GeV c.m. energy W with a precision of typically ± 5.2%. R is found to be constant with an average R = 4.01 ± 0.03 (stat) ± (syst.) for W ? 14 GeV. Quarks are found to be point-like, the mass parameter describing a possible quark form-factor being larger than 186 GeV. Fits including QCD corrections and a weak neutral-current contribution are presented.     

Photoproduction of negative pions on a polarized neutron target in the resonance region

At the Bonn 2.5 GeV electron synchrotron the first measurements of the target asymmetry for the reaction γ + n ↑ → π^? + p have been performed. The negative pions were detected in a magnetic spectrometer at a constant pion c.m. angle of 40° and photon energies between 0.45 GeV and 2.0 GeV. Deuterated butanol was used as target material. The polarization of the deuterons was about 16%. The results show a significant difference from the previously measured π⁺ asymmetry.     

Measurement of coherent pion-photoproduction on the 3He/3H isodoublet

Neutral and charged pion-photo production on ${}^3\text{H}$ and ${}^3\text{He}$ nuclei have been observed in the Δ(1232) resonance region. Resonance averaged cross-sections are presented as functions of momentum transfer.     

Etude par effusiometrie de torsion des proprietes thermodynamiques en phase solide des laitons binaries (Cu,Zn)

The Gibbs thermodynamic variables which we have determined for thirteen brass alloys (Cu, Zn) are in good accord with the literature. The experimental conditions were as close as possible to those of sublimation in static vacuum. The application of the test of the third law in β-brass shows that our free enthalphy measurements are in agreement with the measurements of specific heat by Moser. The primary solid solution α copper of the binary brasses shows quasi-regular behaviour over the whole composition range. Our measurements seem to indicate the existence of a β′/(α + γ) eutectoïd at a temperature less than 100°C. The high degree of order of the γ phase is seen in the large negative values of excess entropy.     

Piles de mesure àélectrolyte solide utilisant une ou deux électrodes ponctuelles en régime transitoire: I. Application à la mesure des enthalpies libres standards d'oxydation des métaux purs

The point electrode is a metal point touching a solid electrolyte (calcia stabilized zirconia), in an atmosphere with a controlled oxygen partial pressure. The system is equipped with an oxygen pump mounted before the cell, which is electronically controlled and attains 10^?20 atm O₂. The potential-time curves of the depolarisation of the point electrode permits a dynamic study of the oxidation of the metal, or of the reduction of its oxide. The point electrode has a very small inertia; the steps on the potential-time curves, even when strongly inclined, can be used to determine the standard free enthalpies of oxidation of pure metals. The measuring cell can be equipped, either with one point electrode associated with a reference electrode at a stable potential, or with two point electrodes placed side by side without any separation. The results obtained for the systems $\text{Cu}\text{Cu}{}_2\text{O}$ and $\text{Co}\text{CoO}$ serve as applications.     

The Category of Ladders

In the first part of this paper we introduce the category of ladders and develop the underlying theory. A ladder consists of a sequence of vector spaces (V _n ) and linear operators ${(A^+_n), (A^-_n)}$ acting between these vector spaces in ascending and descending direction. Unlike as in classical quantum mechanics ladders are defined as objects of a category, the corresponding notion of ladder homomorphisms allows to perform a mathematically structural and rigorous analysis of ladder theory. We allow dependence on n for spaces and operators in the ladder. The job in ladder theory is to find SIE-subladders, on which the Intrinsic Endomorphisms ${A^-_n A^+_n}$ and ${A^+_n A^-_n}$ act as Scalars α _n . A fundamental ladder theorem will provide conditions on the (generalized) commutators or anticommutators assuring the existence of SIE-subladders. The second part contains examples of ladders from classical quantum mechanics, such as the Heisenberg ladder, the Dirac ladder the ladder for the Lie algebra ${{\bf sl}(2,\mathbb{C})}$ . Whereas these classical examples are distinguished by constance of operators and spaces, we then show how the generalized ladder theory allows to handle deformations: h-discretization, q-discretization and “periodization”. Other examples come from orthogonal polynomials. The Legendre, Laguerre and Bessel ladder are presented. Ladder theory allows a certain “anticommutator factorization” of the relevant second order differential operators. In a final section we apply ladder theory to ladders that are at the same time complexes. This enables us to give a transparent structural proof of Hodge’s theorem. The idea of ladder operators and factorization is well-known in quantum mechanics and quantum field theory. The book of Shi-Hai Dong (Factorization method in quantum mechanics, Springer, Dordrecht, 2007) contains a good survey of applications in physics, it provides historical background and links to sources in the physics literature. Note that our approach is independent—not only with respect to notation—of that in Shi-Hai Dong (Factorization method in quantum mechanics, Springer, Dordrecht, 2007).     

An Application of Calculus on Measure Chains to Fourier Theory and Heisenberg's Uncertainty Principle

We present "one-dimensional" Fourier theory on commutative groups T hH , 0 h h < X , 0< H h X within the framework of the so-called calculus on measure chains (or time scales). Depending on certain values of the graininess h and length H of the group the four classical types of Fourier transform are covered: Fourier integral ( T 0 X = R ), Fourier series ( T 1 X = Z ), Fourier analysis of periodic functions ( T 0,2 ~ = S 1 (0) unit circle) and discrete Fourier transform ( T 1 N = Z N ). We will present Fourier theory on these groups in a unified manner. This also allows to closely track the roles of the graininess h and length H of the group--especially for h M 0 and H M X . In the final part of the paper, we investigate the solution of a fundamental equation on T hH , which can be considered as a generalization of the Gauss function. It finally leads to a version of the Heisenberg uncertainty principle, which extends the classical one, valid for T 0 X = R , to the case T hH , where either h >0 or H < X .