Do the fundamental physical constants have the same values in different regions of space-time?

An analysis of quasar spectra yields highly reliable constraints on the possible variation of the fine-structure constant a and the proton-to-electron mass ratio μ during cosmological evolution from the epoch corresponding to a cosmological red shift z≈2.8 (i.e., ∼10¹⁰ years ago) to the current epoch and . Zh. Tekh. Fiz. 69, 1–5 (September 1999)     

Solution of two mutually-reducible problems in electrostatics

There are two well-known problems in electrostatics whose solutions reduce to each other. One of them is that of a grounded conductor containing a cavity with given boundary . A charge distribution is specified on another surface S inside the cavity, or within the volume enclosed by S. It is required to find the charge density induced on . The other problem is that of finding “equivalent” sets of charges (producing identical external fields). Here again there are surfaces and S and the same original distributed charge as in the first problem, but the system is now in empty space and the problem is to find the charge distribution on that produces the same external field as the given distribution on S. Mutual reducibility means that it is sufficient to consider one of the two problems, say, the second. The problem examined in this paper is that of confocal ellipsoids S and and charge distributions described in terms polynomial functions of Cartesian coordinates. The method of multipole moments which leads directly to the solution (i.e., without the need to evaluate the field) is described. Analytical solutions are given for simple surface and volume charge distributions. Special and limiting cases are examined, including degenerate surfaces S and in the form of confocal elliptic cylinders. Zh. Tekh. Fiz. 67, 1–6 (April 1997)     

Atomic structure of silver clusters on silicon

The atomic structure of silver clusters formed on a Si(111)-7×7 single crystal surface by annealing a silver thin film condensed at room temperature is investigated by the diffraction of medium-energy quasielastically scattered electrons. Simulation of the diffraction pattern obtained within a nearly complete electron reflection hemisphere shows that the silver islands formed on the silicon have an ordered structure and a fixed orientation relative to the substrate. Close-packed Ag(111) monolayers, which form a face-centered cubic structure, are arranged parallel to the surface, the direction of these microcrystals being antiparallel to the axis of the substrate. Zh. Tekh. Fiz. 67, 62–66 (December 1997)     

Present and future experiments in nonequilibrium reactor antineutrino energy spectrum

Considerable efforts that have been undertaken in recent years in low-energy antineutrino experiments require further systematic investigations in line of reactor antineutrino spectroscopy as a metrological basis of these experiments. We consider some effects associated with the nonequilibrium of reactor radiation and residual emission from spent reactor fuel in contemporary experiments. The text was submitted by the authors in English.     

BV Structure of the Cohomology of Nilpotent Subalgebras and the Geometry of(W) Strings

Given a simple, simply laced, complex Lie algebra corresponding to the Lie group G, let be thesubalgebra generated by the positive roots. In this Letter we construct aBV algebra whose underlying graded commutative algebra is given by the cohomology, with respect to , of the algebra of regular functions on G with values in . We conjecture that describes the algebra of allphysical (i.e., BRST invariant) operators of the noncritical string. The conjecture is verified in the two explicitly known cases, ₂ (the Virasoro string) and ₃ (the string).     

On the Yangian Y $$(\mathfrak{g}\mathfrak{l}_{m|n} )$$ and its quantum Berezinian

Jonathan Brundan and Alexander Kleshchev recently introduced a new family of presentations for the Yangian Y of the general linear Lie algebra . In this article, we extend some of their ideas to consider the Yangian Y of the Lie superalgebra . In particular, we give a new proof of the result by Nazarov that the quantum Berezinian is central. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

Polarization effect in langasite crystals

The variation of the resonance frequency of piezoelectric resonators subjected to a constant electric field is demonstrated with longitudinal vibrations in La₃Ga₅SiO₁₄ (langasite) crystal rods at temperatures between −60 and +80°C. For the rods whose longtudinal axis makes angle α with the crystal axis in the plane of the axes and [0001], the change in the frequency is proportional to the field strength and depends on α. For a field of ±1.5 × 10⁶ V/m and α = 15°, the relative change in the frequency is ±120 × 10⁻⁶. It is shown that La₃Ga₅SiO₁₄ crystals offer a set of physical parameters that makes them promising for electrically controlled acoustoelectronic devices and for devices based on nonlinear interaction between acoustic waves.     

Theoretical analysis of collisional shift and broadening of antiprotonic helium spectral lines

Effect of medium density on shift and broadening of ( ) spectral lines is considered in the framework of binary-collision approximation with an effective ( )–He potential including the long-range attraction and short-range repulsion. Quantum calculations of the scattering phase shifts at reasonable values of the potential parameters allow to explain the main features of the observed density effect on the shape of ( ) spectral lines in low-temperature helium. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Generator for the Weert Superpotential

Weert found a superpotential for the bounded part of the Maxwelltensor associatedto the Lienard–Wiechert field. Here we obtain afourth-rank generator for the superpotential .     

Comparative analysis of real and \mathcal{P}\mathcal{T}-symmetric Scarf potentials

The Scarf I and Scarf II potentials are discussed within a common mathematical framework, which is then specified to handle the two potentials separately both in the conventional Hermitian and in the -symmetric setting. The physically admissible solutions are identified in each case together with the corresponding energy eigenvalues. Several main differences between the -symmetric Scarf I and II potentials are pointed out. These include the presence and absence of the quasi-parity quantum number, the sign of the pseudo-norm, the mechanism of the spontaneous breakdown of symmetry and the non- orthogonality of otherwise admissible solutions in the Scarf I potential. Similarities and differences with respect to the corresponding Hermitian systems are also pointed out.     

On the Product of Real Spectral Triples

The product of two real spectral triples and , the first of which is necessarily even, was defined by A.Connes as given by and, in the even-even case, by . Generically it is assumed that the real structure obeys the relations , , , where the -sign table depends on the dimension n modulo 8 of the spectral triple. If both spectral triples obey Connes' >-sign table, it is seen that their product, defined in the straightforward way above, does not necessarily obey this -sign table. In this Letter, we propose an alternative definition of the product real structure such that the -sign table is also satisfied by the product.     

Observable N \overline N oscillation, high-scale see-saw and origin of matteroscillation, high-scale see-saw and origin of matter

See-saw mechanism has been a dominant paradigm in the discussion of neutrino masses. We discuss how this idea can be tested via a baryon number violating process such as N- oscillation. Since the expected see-saw scale is high and the N- amplitude goes like M _R ⁻⁵ , one might think that this process is not observable in realistic see-saw models for neutrino masses. In this talk I show that in supersymmetric models, the above conclusion is circumvented leading to an enhanced and observable rate for N oscillation. I also discuss a new mechanism for baryogenesis in generic models for neutron-anti-neutron oscillation.     

Preferred Invariant Symplectic Connections on Compact Coadjoint Orbits

Let be the Haag--Kastler net generated by the (2) chiral current algebra at level 1. We classify the SL(2, )-covariant subsystems by showing that they are all fixed points nets ^H for some subgroup H of the gauge automorphisms group SO(3) of . Then, using the fact that the net ₁ generated by the (1) chiral current can be regarded as a subsystem of , we classify the subsystems of ₁. In this case, there are two distinct proper subsystems: the one generated by the energy-momentum tensor and the gauge invariant subsystem .     

High precision X-ray spectroscopy in hydrogen-like fermionic and bosonic atomic systems

Some time after its formation an exotic atom may be considered a hydrogen-like system consisting of a nucleus and an exotic particle in a bound state. In this situation it is an ideal tool to study cascade properties, while for the innermost orbits it can be used to probe the interaction with the nucleus. From an extended series of experiments using high resolution X-ray spectroscopy for both aspects typical examples are reported and preliminary results are given: 1. To determine the complex scattering length in H the hyperfine transitions have been measured. 2. To determine the pion mass the 5 4 transitions in N have been studied. In all cases a major contribution to the uncertainty originates from the calibration. Therefore a new method is proposed that will establish a universal set of high precision calibration lines for pionic, muonic and electronic systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

A study of the nuclear-medium influence on neutral-strange-particle production in deep-inelastic neutrino scattering

The influence of nuclear effects on the production of neutral strange particles (V ⁰) is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with E _v =3−30 GeV) at the Serpukhov accelerator. The mean multiplicity of V ⁰ particles in nuclear interactions, , is found to exceed significantly that in “quasideuteron” interactions, . The ratio of is larger than that for π⁻ mesons, . It is shown that the multiplicity gain of V ⁰ particles can be explained by intranuclear interactions of produced pions. The text was submitted by the authors in English.     

Laser spectroscopy of the antiprotonic helium atom–molecule {\bar pHe}^+

The metastable antiprotonic helium atom–molecule (in short, atomcule), , which was discovered in 1991 as being the cause of the anomalous longevity of antiprotons with an overall lifetime of about 3 μs, now provides an exotic playground for laser spectroscopy, helped by the existence of numerous long lived states with 1–2 μs lifetimes. This three body system is characterized by a large angular momentum l ∼ 38 of coupled with the electron in the 1s ground orbital, and looks like an exotic hydrogen isotope with many different “nuclear states” as well as an exotic molecule with two centers (He²⁺ and ). So far, a number of laser resonance transitions have been identified. The present talk will cover the following topics: (1) high precision spectroscopy in comparison with three body theories involving the relativistic effect and QED, and (2) hyperfine structure of ;laser-microwave triple resonance. This revised version was published online in August 2006 with corrections to the Cover Date.     

New Simple Method for Obtaining Integrable Hierarchies of Soliton Equations with Multicomponent Potential Functions

A new simple method for obtaining integrable hierarchies of soliton equations is proposed. First of all, a new loop algebra is constructed, whose commutation operation is clear as that in loop algebra . Second, by making use of the Tu scheme, many of integrable hierarchies with multicomponent potential functions can be produced. As a specific application of our method, a multicomponent AKNS hierarchy is obtained. Finally, an expanding loop algebra of the loop algebra is constructed. Taking advantage of above, a type of integrable coupling system of the multicomponent AKNS hierarchy is worked out.