Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering

The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model, where the quark loops (in the mean field approximation) and the meson loops (in the $1/N_c$ approximation) are taken into account. We show that quark loop contribution dominates, because the meson loops strongly conceal each other. The sigma-pole contribution $(m^2_\sigma-t)^{-1}$ plays the main role and contains strong t-dependence of the effective pion polarizability at the region $|t|\geq 4M_\pi^2$. Possibilities of experimental test of this sigma-pole effect in the reaction of Coulomb Nuclear Scattering are estimated for the COMPASS experiment.Comment: 11 pages, 8 figure

Anomalous transport in normal-superconducting and ferromagnetic-superconducting nanostructures

We have calculated the temperature dependence of the conductance variation ($\delta S(T)$) of mesoscopic superconductor normal metal(S/N) structures, in the diffusive regime, analysing both weak and strong proximity effects. We show that in the case of a weak proximity effect there are two peaks in the dependence of $\delta S(T)$ on temperature. One of them (known from previous studies) corresponds to a temperature $T_1$ of order of the Thouless energy ($\epsilon_{Th}$), and another, newly predicted maximum, occurs at a temperature $T_2$ where the energy gap in the superconductor $\Delta(T_2)$ is of order $\epsilon_{Th}$. In the limit $L_{\phi}<L$ the temperature $T_1$ is determined by $D \hbar /L^2_{\phi}$ ($L_{\phi}$ is the phase breaking length), and not $\epsilon_{Th}$. We have also calculated the voltage dependence $\delta S(V)$ for a S/F structure (F is a ferromagnet) and predict non-monotonic behaviour at voltages of order the Zeeman splitting.Comment: 6 figures. Submitted to PRB Rapid com

Energy Resolved Supercurrent between two superconductors

In this paper I study the energy resolved supercurrent of a junction consisting of a dirty normal metal between two superconductors. I also consider a cross geometry with two additional arms connecting the above mentioned junction with two normal reservoirs at equal and opposite voltages. The dependence of the supercurrent between the two superconductors on the applied voltages is studied.Comment: revtex, 7 pages, 8 figures. accepted by Phys. Rev.

1/N_c- expansion of the quark condensate at finite temperature

Previously the quark and meson properties in a many quark system at finite temperature have been studied within effective QCD approaches in the Hartree approximation. In the present paper we consider the influence of the mesonic correlations on the quark self-energy and on the quark propagator within a systematic $1/N_c$- expansion. Using a general separable ansatz for the nonlocal interaction, we derive a selfconsistent equation for the $1/N_c$ correction to the quark propagator. For a separable model with cut-off formfactor, we obtain a decrease of the condensate of the order of 20\% at zero temperature. A lowering the critical temperature for the onset of the chiral restoration transition due to the inclusion of mesonic correlations is obtained what seems to be closer to the results from lattice calculations.Comment: 19 pages, REVTeX, 5 figure

Civic patriotism among young sportsman in the South of Russia: Sociological analysis and diagnostics

Purpose: This article is aimed at revealing the specifics of civil and Patriotic practices in the youth environment of the South Russian region. Methodology: The sociological study used methods of qualitative operational analysis and theoretical interpretation of the obtained empirical data, as well as methods of sociological diagnostics aimed at the conceptual generalization of the results of empirical research by social recognition of the qualitative characteristics of civil patriotism in the youth environment as an integral social phenomenon. Result: In modern Russian society, patriotism is positively perceived by the majority, including young Russians, who associate it with love for the Motherland and a willingness to stand up for it. However, state patriotism in the youth environment lacks citizenship, that is, the desire of young people to actively participate in social Affairs, working for the benefit of society and the social environment. Applications: This research can be used for the universities, teachers and students. Novelty/Originality: The sociological analysis and diagnostics reveal the reasons for the low level of civic patriotism among young people, as well as the factors that hinder its development in regional communities in the South of Russia.The article was completed as part of the implementation of the State Assignment (Ministry of Education and Science of the Russian Federation), project No. 28.3486.2017 / PC “Civil patriotism in the formation and development of solidarity practices in the south of Russia: resource potential and conditions for its implementation”

Bulk-boundary correspondence in three dimensional topological insulators

We discuss the relation between bulk topological invariants and the spectrum of surface states in three dimensional non-interacting topological insulators. By studying particular models, and considering general boundary conditions for the electron wavefunction on the crystal surface, we demonstrate that using experimental techniques that probe surface states, only strong topological and trivial insulating phases can be distinguished; the latter state being equivalent to a weak topological insulator. In a strong topological insulator, only the {\it parity} of the number of surface states, but not the number itself, is robust against time-reversal invariant boundary perturbations. Our results suggest a \z definition of the bulk-boundary correspondence, compatible with the \z classification of topological insulators.Comment: TeXLive (Unix), revtex4-1, 7 pages, 3 figure

Lattice WW algebras and quantum groups

We represent Feigin's construction [22] of lattice W algebras and give some simple results: lattice Virasoro and $W_3$ algebras. For simplest case $g=sl(2)$ we introduce whole $U_q(sl(2))$ quantum group on this lattice. We find simplest two-dimensional module as well as exchange relations and define lattice Virasoro algebra as algebra of invariants of $U_q(sl(2))$. Another generalization is connected with lattice integrals of motion as the invariants of quantum affine group $U_q(\hat{n}_{+})$. We show that Volkov's scheme leads to the system of difference equations for the function from non-commutative variables.Comment: 13 pages, misprints have been correcte