Exponential clustering for long-range integer-spin systems

By using Kirkwood-Salsburg equations for classical spin systems with unbounded integer values we prove exponential decay (resp. power law decay) for exponential (resp. power law) decaying potentials. We use these results to prove the mass gap in the two-dimensional Higgs-Villain model in the weak coupling region.Research partially supported by the National Science Foundation under Grant PHY-77-18762On leave from Department of Mathematics, University of British Columbia, Vancouver, B. C., Canada. Research partially supported by National Research Council under Grant A4015On leave from Istituto di Fisica Teorica, Napoli, Italy     

Multicatalytic asymmetric synthesis of complex tetrahydrocarbazoles via a Diels-Alder/benzoin reaction sequence

Expanding upon the recently developed aminocatalytic asymmetric indole-2,3-quinodimethane strategy, a straightforward synthesis of structurally and stereochemically complex tetrahydrocarbazoles has been devised. The chemistry's complexity-generating power was further harnessed by designing a multicatalytic, one-pot Diels-Alder/benzoin reaction sequence to stereoselectively access trans-fused tetracyclic indole-based compounds having four stereogenic centers with very high fidelity.     

Measurement of the K S mean lifetime from π+π− and π0π0 decays using K L decays to determine the acceptance

A precision measurement of the K _S mean lifetime has been performed by comparing, in the same experimental setup, the distributions of two-pion decays of neutral kaons produced by high energy proton-beryllium interactions in two targets at a relative distance variable between 112 and 160 m. The value obtained combining the results from π⁺π^? and π⁰π⁰ decays is τ_s = (0.8971 ± 0.0021) 10^?10 s.     

Inclusive π0 production at very large pT at the ISR

Inclusive π⁰ production at 90° has been studied at the ISR at $\text{s}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 52.7}\text{and}\text{62.4}\text{GeV}$ over the p_T range from 7 to 15 GeV/c. The two photons from π⁰ decay yielded overlapping electromagnetic showers in the liquid-argon-Pb plate calorimeter detector system. Any direct photon production is included in these measurements. For large values of p_T, the cross section is observed to decrease with p_T more slowly than the p_T^?8 behaviour which has been observed at lower values of p_T.     

Ion-beam sputtering deposition of CsI thin films

Stoichiometric CsI thin films were deposited by Ar ion-beam sputtering of a CsI target at room temperature. The sputtered 100-nm thick CsI films obtained were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and quantum efficiency (QE) measurements. As it was expected, the chemical, morphological, crystalline and photo-emissive properties of CsI films obtained depended on the deposition parameters. Comparison with results obtained for evaporated CsI films indicated that surface morphology, i.e., the effective photo-emissive surface area, is one of the important parameters in influencing the QE . PACS 81.15.-z; 79.60.Dp; 68.37.Ps     

BCS quasi-particle tunnelling current in Josephson tunnel junctions

Summary The recent improvements in the fabrication technology have succeeded in obtaining high-quality Josephson tunnel junctions. TheI–V characteristics of these junctions exhibit now lesser and lesser differences from the theoretical predictions. The various figures of merit, so far introduced to qualify the junctions, appear now focused on too limited aspects and a direct comparison with the detailed prediction of the theory is in order. For this awaken interest in the detailed predictions of the BCS theory, we have revisited the relevant formulae for the quasi-particle tunnelling current. A detailed discussion of the analytical transformation necessary for a simple numerical evaluation of this current is reported. SeveralI–V curves are obtained using the parameter values corresponding to the case of Nb-based junctions, which is the actual running technology. Peculiar interesting aspects are outlined.     

Closed form solutions for the self-resonances in a short Josephson junction

We present a closed form solution for the self-resonances in a short Josephson tunnel junction. This solution is alternative to the well-known textbook result (Barone and Paternó (1982) and Kulik (1965)) [1] and [2] based on a series expansion. Results are derived for the up-to-date case of a 0-π junction.