Interface delocalization in the three-dimensional Ising model

The interface delocalization in the three-dimensional Ising model is studied by real-space renormalization group methods. The first-order cumulant expansion approximation is used. Defect free energies for a boundary plane of defects and an internal plane of defects are calculated in the whole temperature region. The phase diagrams are also obtained. The method and the model analyzed may give a correct phase diagram only in the regime of continuous interface delocalization. The interface delocalization is obtained for the boundary defect and also for the internal defect if the systems on two sides of the internal defect plane have a different degree of order. The delocalization transition does not occur in the case of the internal defect plane between two equally ordered systems.     

Quarks and leptons as composite goldstone fermions

A dynamical scheme for composite quarks and leptons is proposed in which the observed fermions are Goldstone particles of spontaneously broken supersymmetry. Their residual interactions are described by a minimal effective lagrangian which invokes a non-linear realization of sypersymmetry. Possible experimental consequences are studied and it is found that the most conspicuous signature of this scheme would be a dramatic increase in the lepton pair production in hadronic collisions, particularly in $\text{pp}$ scattering, at high energy.     

Retardation effects in ion-ion collisons

The modification of the two center screened electronic Coulomb potential due to relativistic kinematical effects is investigated in the Coulomb gauge. Both nuclear and electronic charges were approximated by Gaussian distributions. For ion velocitiesv/c =0.1 the effect may roughly be approximated by a 0.1 % increase in the effective strength for the monopole term of the two center potential. Thus for ion kinetic energies not exceeding a few MeV/nucleon this relativistic contribution induces small effects on the binding energy of the 1σ-electrons except for super critical charges.     

Ligand field splitting in seven coordinated NbF 7 2− -type complexes

The splittings ofd-orbitals for seven coordinated complexes of the type NbF₇ ^2– is calculated using a point charge model. The perturbed energies are expressed as a function of =G ₂/G ₄. The results are very sensitive on assumed geometrical angles of the molecule.

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Zusammenfassung Es wurde die Aufspaltung derd-Zustände für siebenkoordinierte Komplexe des NbF₇ ^2– Typs mittels eines Punktladungsmodells berechnet. Die Störungsenergien werden als Funktion von =G ₂/G ₄ gegeben. Die Ergebnisse hängen empfindlich von den angenommenen Bindungswinkeln ab.

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Résumé La séparation des orbitalesd dans les complexes à sept ligandes du type NbF₇ ^2–est calculée d'après la méthode à charges ponctuelles. Les énergies de perturbation sont données en fonction de =G ₂/G ₄. Les résultats sont très sensibles envers les angles de valence adoptés.

     

Electron density measurements during a current perturbation of a wall stabilized argon arc

The paper describes the application of a laser interferometric technique to the measurement of electron density changes which occur when a d.c. argon arc is subjected to a current step or a.c. modulation. The frequency of the latter was varied from 50 to 30,000 Hz. A first attempt is made to derive mobility measurements from the data.     

A note on the Lüders-Von Neuman formula of collapse

The collapse in a quantum-mechanical measurement is treated as a physical process, described by a superoperator mapping states into states and depending only on the measured observable. The assumption that the states with a sharp value of the measured observable remains unchanged yields the Lüders-Von Neuman formula.