The radial excitations of η−η′ mesons

The possibility of identification of a number of the recently discoveredJ ^PC=0^?+ isosinglet resonances (the ζ(1275), ι(1460) and others) as radial excitations of the η(549)- and η′(958)-mesons is investigated within the earlier developed phenomenological approach to analyse radial excitations of light mesons. The widths of the electromagnetic and strong decays of these mesons and the branching ratios of their production in the radiativeJ/ψ decay, as well as in the π^- p charge exchange reaction, are estimated. It is pointed out that the abundant production of the ι-meson in theJ/ψ-decays and the small width of the ι→2γ decay put forward repeatedly as an evidence for the glueball nature of this meson, can qualitatively be obtained in one of the considered schemes of the radial excitations of the η?η′-system.     

Epidemic dynamics in a heterogeneous incompletely isolated population with allowance for seasonal variations in the infection rate

Mathematical parasite-host models are generalized to the case when the population members differ in susceptibility and contagiousness, there is an external source of infection, and the model parameters depend periodically (seasonally) on time. The model is proved to have a periodic solution that is unique and exponentially stable for sufficiently small periodic oscillations of the coefficients.     

Experimental Study of Ar-Gas Radiation Behind the Front of a Strong Shock Wave

Journal of Applied Spectroscopy - Emission spectra of argon behind the front of a strong shock wave are studied in the range of shock-wave velocities of 4.6–8.3 km/s and pressures before the...     

Low-Frequency Optically Detected EPR of Sm<Superscript>3+</Superscript> in Cs<Subscript>2</Subscript>NaYF<Subscript>6</Subscript> Single Crystal

The Sm³⁺ ion in the Cs₂NaYF₆ single crystal was studied by optically detected electron paramagnetic resonance spectroscopy. Magnetic resonance signals were recorded by Faraday rotation at the frequency of 0.6–0.85 GHz and magnetic fields of about 0.14 T. The hyperfine parameters of ¹⁴⁷Sm³⁺ and ¹⁴⁹Sm³⁺ isotopes were determined.     

On q-Deformed $${{\mathfrak{gl}}_{\ell+1}}$$-Whittaker Function III

In this paper, we identify q-deformed \mathfrakgl_l+1{\mathfrak{gl}_{\ell+1}}-Whittaker functions with a specialization of the Macdonald polynomials. This provides a representation of q-deformed \mathfrakgl_l+1{\mathfrak{gl}_{\ell+1}}-Whittaker functions in terms of the Demazure characters of affine Lie algebra [^(\mathfrakgl)]_l+1{\widehat{\mathfrak{gl}}_{\ell+1}}. We also define a system of dual Hamiltonians for q-deformed \mathfrakgl_l+1{\mathfrak{gl}_{\ell+1}}-Toda chains and give a new integral representation for the q-deformed \mathfrakgl_l+1{\mathfrak{gl}_{\ell+1}}-Whittaker functions. Finally, we represent the q-deformed \mathfrakgl_l+1{\mathfrak{gl}_{\ell+1}}-Whittaker function as a matrix element of a quantum torus algebra.     

Special features of thermal evaporation of rare-earth metals

The process of thermal evaporation of rare-earth metals (Ce-Yb) with an incomplete 4f-shell is discussed in terms of electronic structure of their surface. Evaluation of the surface density of neutral intrinsic atoms determining the evaporation process is made. The fact of detachment of Sm atoms in the lowest excited 4f⁵5d6s²-state from the surface is experimentally demonstrated. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 43–47, June, 2006.     

Influence of indentation-forming conditions on the estimation of the photomechanical effect

The anisotropy, spectral dependence, and time dependence of relaxation of the dimensions of microhardness indentations in silicon are investigated. It is shown that the time and spectral dependences correlate with the density of excited carriers in the (defective and elastically deformed) region in which they are excited, and the anisotropy is determined by various types of deformations of the chemical bonds for different positions of the indenter. Fiz. Tverd. Tela (St. Petersburg) 40, 503–504 (March 1998)     

Calculations on the mechanism of ion polymerization in the formaldehyde crystal

A number of possible crystal structures of formaldehyde are calculated using an atom—atom scheme in order to explain some phenomena observed in the low-temperature solid-state polymerization of this and related systems. The structures whose molecular packing favours the polymerization are shown to represent local energy minima. Studies of various molecular motions in so calculated crystals support the hypothesis that polymer chains move spontaneously at the propagation stage. Main peculiarities of the solid-state polymerization mechanism are formulated on the basis of the present and previous calculations.     

Experimental studies of passive correlation tomography of incoherent acoustic sources in the megahertz frequency band

Correlation properties of thermal acoustic radiation in the megahertz frequency band are studied experimentally. The amplitudes of correlation peaks measured at the sum of the delays that correspond to the direct signal propagation between the piezoelectric transducers are found to depend on the relative transducer positions. This effect is explained by a possible difference between the receive patterns of the transducers and the patterns of their intrinsic thermal radiation. The correlation of signals received from a spatial region heated above the ambient medium is measured. The correlation between the received signals is found to depend on the time of heating of the emitter’s working medium. Numerical calculation of temperature distributions and the allowance for the decorrelation effect due to the spatial extent of the source provide a quantitative agreement between the theoretical and experimental results. Estimates of the spatial resolution achievable with the given experimental configuration show that it is close to the coherence length of the received radiation.