The QCD vacuum, confinement and strings in the Vacuum Correlator Method

In this review paper the QCD vacuum properties and the structure of color fields in hadrons are studied using the complete set of gauge-invariant correlators of gluon fields. Confinement in QCD is produced by the correlators of some certain Lorentz structure, which violate abelian Bianchi identities and therefore are absent in the case of QED. These correlators are used to define an effective colorless field, which satisfies Maxwell equation with nonzero effective magnetic current. With the help of the effective field and correlators it is shown that quarks are confined due to effective magnetic currents, squeezing gluonic fields into a string, in agreement with the ``dual Meissner effect''. Distribution of effective gluonic fields are plotted in mesons, baryons and glueballs with static sources.Comment: 36 pages, 19 figures, to appear in UFN, updated version. Few references added, minor difference

Coupled quantum wires

We study a set of crossed 1D systems, which are coupled with each other via tunnelling at the crossings. We begin with the simplest case with no electron-electron interactions and find that besides the expected level splitting, bound states can emerge. Next, we include an external potential and electron-electron interactions, which are treated within the Hartree approximation. Then, we write down a formal general solution to the problem, giving additional details for the case of a symmetric external potential. Concentrating on the case of a single crossing, we were able to explain recent experinents on crossed metallic and semiconducting nanotubes [J. W. Janssen, S. G. Lemay, L. P. Kouwenhoven, and C. Dekker, Phys. Rev. B 65, 115423 (2002)], which showed the presence of localized states in the region of crossing.Comment: 11 pages, 10 figure

Kramers-Kronig constrained variational analysis of optical spectra

A universal method of extraction of the complex dielectric function $\epsilon(\omega)=\epsilon_{1}(\omega)+i\epsilon_{2}(\omega)$ from experimentally accessible optical quantities is developed. The central idea is that $\epsilon_{2}(\omega)$ is parameterized independently at each node of a properly chosen anchor frequency mesh, while $\epsilon_{1}(\omega)$ is dynamically coupled to $\epsilon_{2}(\omega)$ by the Kramers-Kronig (KK) transformation. This approach can be regarded as a limiting case of the multi-oscillator fitting of spectra, when the number of oscillators is of the order of the number of experimental points. In the case of the normal-incidence reflectivity from a semi-infinite isotropic sample the new method gives essentially the same result as the conventional KK transformation of reflectivity. In contrast to the conventional approaches, the proposed technique is applicable, without readaptation, to virtually all types of linear-response optical measurements, or arbitrary combinations of measurements, such as reflectivity, transmission, ellipsometry {\it etc.}, done on different types of samples, including thin films and anisotropic crystals.Comment: 10 pages, 7 figure

BARRIERS IN PROFESSIONAL DEVELOPMENT OF WOMEN

Purpose: The current situation shows that women, in comparison with men, are a more vulnerable social group. Gender stereotypes lead to an underestimation of the abilities of women and their labor input. Methodology: The paper analyzes two groups of gender stereotypes, which in fact represent barriers that impede the professional development of women in the Russian labor market.  The authors established a level of agreement with the influence of barriers on female professional activity in two groups of respondents - women with or without professional experience.  Result: The authors identified and compared the leading barriers to female professional activities. In general, in the structure of the female professional mentality, there are certain personal stereotypes that, together with socially determined gender stereotypes, have a complex impact on unlocking the female employment potential. Applications: This research can be used for universities, teachers, and students. Novelty/Originality: In this research, the model of barriers in the professional development of women is presented in a comprehensive and complete manner

Multi-component magneto-optical conductivity of multilayer graphene on SiC

Far-infrared diagonal and Hall conductivities of multilayer epitaxial graphene on the C-face of SiC were measured using magneto-optical absorption and Faraday rotation in magnetic fields up to 7 T and temperatures between 5 and 300 K. Multiple components are identified in the spectra, which include: (i) a quasi-classical cyclotron resonance (CR), originating from the highly doped graphene layer closest to SiC, (ii) transitions between low-index Landau levels (LLs), which stem from weakly doped layers and (iii) a broad optical absorption background. Electron and hole type LL transitions are optically distinguished and shown to coexist. An electron-hole asymmetry of the Fermi velocity of about 2% was found within one graphene layer, while the Fermi velocity varies by about 10% across the layers. The optical intensity of the LL transitions is several times smaller than what is theoretically expected for isolated graphene monolayers without electron-electron and electron-phonon interactions.Comment: 9 pages, 6 figure