On the Inverse Scattering Transform for the Kadomtsev-Petviashvili Equation

The initial value problem of the Kadomtsev-Petviashvili equation for one choice of sign in the equation has been recently investigated in the literature. Here we consider the other choice of sign. We introduce suitable eigenfunctions which though bounded are not analytic in the spectral parameter. This, in contrast to the known case, prevents us from formulating the inverse problem as a nonlocal Riemann-Hilbert boundary value problem. Nevertheless a suitable formulation is given and a formal solution is constructed via a linear integral equation.     

The pomeron colour structure and hadron scattering on the six-quark deuteron configuration

The pomeron colour structure provides some contribution to the elastic hadron-deuteron amplitude not contained in the Glauber like approach. This contribution is very sensitive to the short distance behaviour of the deuteron wave function and poses one to fix with a high precision a size of the deuteron six-quark bag.     

Circular polarization of gamma quanta in the radiative capture of polarized thermal neutrons by protons

An experiment to measure the circular polarization of γ-quanta, P_γ, in the reaction of radiative capture of polarized thermal neutrons by protons is described. Solid parahydrogen was employed as a proton target.The circular polarization was found to be P_γ = ?(2.90 ± 0.87) × 10^?3 which is in agreement with the theoretical estimates of P_γ arising from the admixture of the triplet capturing state to the ¹S₀ principal capturing state.     

Parity nonconserving photon circular polarization in np → dγ capture as electroweak effect

It is shown that there exists a relatively large contribution of electroweak nature to parity nonconserving photon circular polarization in np → dγ capture, violating the Siegert theorem.     

Flavored exotic multibaryons and hypernuclei in topological soliton models

The energies of baryon states with positive strangeness, or anticharm (antibeauty), are estimated in the chiral soliton approach, in the “rigid oscillator” version of the bound-state soliton model proposed by Klebanov and Westerberg. Positive strangeness states can appear as relatively narrow nuclear levels (Θ-hypernuclei), and the states with heavy antiflavors can be bound with respect to strong interactions in the original Skyrme variant of the model (SK4 variant). The binding energies of antiflavored states are also estimated in the variant of the model with a sixth-order term in chiral derivatives added to the Lagrangian to stabilize solitons (SK6 variant). This variant is less attractive, and nuclear states with anticharm and antibeauty can be unstable relative to strong interactions. The chances of obtaining bound hypernuclei with heavy antiflavors increase within the “nuclear variant” of the model with a rescaled model parameter (the Skyrme constant e or e′ decreased by a out 30%), which is expected to be valid for baryon numbers greater than B ～ 10. The rational map approximation is used to describe multiskyrmions with a baryon number of up to about 30 and to calculate the quantities necessary for their quantization (moments of inertia, sigma term, etc.).     

On phonon-wind-driven spin injection and the conductivity mismatch problem

Spin injection from a ferromagnetic metal into a semiconductor driven by a constant phonon flow is considered. It is shown that diffusive (as opposed to electrical) spin injection gives rise to a highly spin-polarized current through the semiconductor. In other words, phonon-wind-driven injection under certain conditions eliminates the conductivity mismatch responsible for reduced spin polarization of the electric current injected from a ferromagnetic metal into a semiconductor.     

Interplay of soft and hard interactions in nuclear shadowing at highQ 2 and lowx

Nuclear shadowing corrections are known to be dominated by soft interactions. They grow as function of 1/x more slowly than the single scattering term, which has an essential contribution from hard interactions. Therefore, we predict that nuclear shadowing vanishes eventually at very lowx, provided thatQ ² is high and fixed. At the same time, at medium and lowQ ², nuclear shadowing grows with 1/x. Our formalism nicely explains also the recent NMC data onQ ²-dependence of the nuclear shadowing. The effect of gluon fusion is found to be of little importance for the nuclear structure function in the available range ofx. Communicated by W. Weise     

A simple synthesis of truxene,a building block for optoelectronics and fullerene fragments

Truxene was efficiently synthesized by reduction of truxenone with excess hydrazine hydrate in diethylene glycol at 180 °C without added base, a variation of the Huang-Minlon Wolff–Kishner reduction. The proposed mechanism highlights hydrazine as a nucleophile and a base, extracting protons from the hydrazone and diazene intermediates.     

Continuous and random Vapnik-Chervonenkis classes

Nous démontrons que si T est une théorie dépendante, sa randomisée de keisler T ^R l’est aussi. Pour faire cela nous généralisons la notion d’une classe de Vapnik-Chervonenkis à des familles de fonctions à valeurs dans [0, 1] (dyune classe de Vapnik-Chervonenkis continue), et nous caractérisons les familles de fonctions ayant cette propriété par la vitesse de croissance de la largeur moyenne d’une famille de compacts convexes associés.