The strength of small-instanton amplitudes in gauge theories with compact extra dimensions

We study instanton effects in theories with compact extra dimensions. We perform an instanton calculation in a 5d theory on a circle of radius R, with gauge, scalar, and fermion fields in the bulk of the extra dimension. We show that, depending on the matter content, instantons of size rho << R can dominate the amplitude. Using deconstruction as an ultraviolet definition of the theory allows us to show, in a controlled approximation, that for a small number of bulk fermions, the amplitude for small size instantons exponentially grows as e^{O(1)R/rho}.Comment: Title modified, references added, typos corrected. Version to appear in JHEP. 24 pages, 1 figur

Amplification of Magnetooptical Response in the «Nanocomposite-Bismuth Telluride» Multilayer System

The presented work is devoted to the study of magneto-optical properties of «nanocompositesemiconductor » ((Co40Fe40B20)33.9(SiO2)66.1/Te3Bi2)) multilayer structures. It has been found, that the adding of Te3Bi2 spacer regardless of composite’s compound increases a magneto-optical response and the amplification of it is the biggest among the other spacers such as Si, SiC and Cu. There has also been established a good correlation between thickness dependencies of magnetooptical (MO) and magnetotransport properties. This correlation is related to the peculiarities of interface forming at the «FM-granule - semiconductor » edge and to percolation process in multilayer structures. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3533

Domain Walls Zoo in Supersymmetric QCD

Solving numerically the equations of motion for the effective lagrangian describing supersymmetric QCD with the SU(2) gauge group, we find a menagerie of complex domain wall solutions connecting different chirally asymmetric vacua. Some of these solutions are BPS saturated walls; they exist when the mass of the matter fields does not exceed some critical value m < m* < 4.67059... There are also sphaleron branches (saddle points of the ebergy functional). In the range m* < m < m** \approx 4.83, one of these branches becomes a local minimum (which is not a BPS saturated one). At m > m*, the complex walls disappear altogether and only the walls connecting a chirally asymmetric vacuum with the chirally symmetric one survive.Comment: 23 pages, LaTeX, 11 figure

Analysis of the selective value of promising Melissa officinalis L. subsp. altissima (Smith.) Arcang variety

The aim of this research was to study a promising MD 1–17 Melissa officinalis L. subsp. altissima (Smith.) Arcang. variety sample obtained in the collection of the gene pool of the Research Institute of Agriculture of Crimea (RIAC) in comparison with Krymchanka (selected in the RIAC) and Lada (selected in the All-Russian research Institute of medicinal and aromatic plants(VILAR) varieties of lemon balm M. officinalis L. subsp. officinalis. In 2017– 2019, in the Department of Essential Oil and Medicinal Plants of the RIAC,a competitive variety trial of lemon balm varieties was conducted in accordance with the methodological recommendations for the selection of essential-oil plants. A territory where this study was conducted belongs to one of the five agroclimatic regions – the upper piedmont, warm, not enough humid; to the northern subarea with moderately mild winters. Weather conditions during the years of competitive variety trial varied significantlya fact that allowed assessing the adaptability of studied variety samples and forecasting the nature of productivity potential realization in different growing conditions. As a result, it was found that MD 1–17 variety sample significantly exceeds other varieties in terms of yield of fresh raw materials, on average, by 62.2 and 77.4%, and in yield of air-dried raw materials, on average, by 32.2 and 52.2%, respectively. In terms of obtaining essential oil from air-dried raw materials, this variety sample exceeds the best in this parameter Crimean variety Krymchanka by 56.3%. Basic components of its essential oil are caryophyllene (25.3–35.9%) and germacrene D (17.7–31.2%) with almost complete absence or insignificant amount of citral (0.1–7.3%); the proportion of latter in essential oils of Krymchanka and Lada varieties can reach 36.6% or more. Novelty of this study includes the creation of the first variety of a new promising essential oil plant –M. altissima. Raw materials of this variety and products of its processing may be of interest for different ways of use, including the perfumery and cosmetics industry, for food purposes as a component of tea compositions, etc

Nonperturbative Corrections to Inclusive Beauty and Charm Decays: QCD versus Phenomenological Models

We present a selfconsistent method for treating nonperturbative effects in inclusive nonleptonic and semileptonic decays of heavy flavour hadrons. These effects give rise to powerlike corrections $\propto 1/m_Q^n\,$, $n \ge 2$ with $m_Q$ denoting the heavy quark mass.The leading correction to the semileptonic branching ratio occurs for n=2. It is expressed in terms of the vector-pseudoscalar mass splitting: \delta BR\ind{sl}/BR\ind{sl} \simeq BR\ind{nl}\, \cdot \,6\,(\,(M_V^2-M_P^2)/m_Q^2)\cdot (c_+^2 - c_-^2)/2N_c and yields a {\it reduction} of BR\ind{sl}. This nonperturbative correction contributes to the nonleptonic width with a sign opposite to that of the perturbative terms that are non-leading in $1/N_c$. In beauty decays the former reduces the latter by 20 \% whereas in charm decays they more or less cancel. This leads to a {\it reduction} of BR\ind{sl} by no more than 10 \% in beauty decays and by a factor of roughly two in charm decays. We confront these results with those obtained from phenomenological models of heavy flavour decays and find that such models are unable to mimic these leading corrections by a specific choice of quark masses or by invoking Fermi motion.Comment: 11 pages (2 figs are not included), Latex file, FERMILAB-PUB-92/158-T UND-HEP-92-BIG04 TPI-MINN-92/30-

Pion form factor and QCD sum rules: case of pseudoscalar current

We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of pseudoscalar pion currents. The essential instanton contribution is reanalysed with account for present more accurate values of parameters entering Single Instanton Approximation (SIA). The theoretical curve obtained for Q^2 dependence of pion form factor is in a good agreement with existing experimental data. To calculate NLO corrections for double spectral densities we developed an effective computational technic. The details of the method together with the results for pion form factor in a more theoretically clean case of axial interpolating currents will be presented elsewhere.Comment: LaTeX file, 12 pages, 5 figures, uses axodraw.st

Can Theta/N Dependence for Gluodynamics be Compatible with 2 pi Periodicity in Theta ?

In a number of field theoretical models the vacuum angle \theta enters physics in the combination \theta/N, where N stands generically for the number of colors or flavors, in an apparent contradiction with the expected 2 \pi periodicity in \theta. We argue that a resolution of this puzzle is related to the existence of a number of different \theta dependent sectors in a finite volume formulation, which can not be seen in the naive thermodynamic limit V -> \infty. It is shown that, when the limit V -> \infty is properly defined, physics is always 2 \pi periodic in \theta for any integer, and even rational, values of N, with vacuum doubling at certain values of \theta. We demonstrate this phenomenon in both the multi-flavor Schwinger model with the bosonization technique, and four-dimensional gluodynamics with the effective Lagrangian method. The proposed mechanism works for an arbitrary gauge group.Comment: minor changes in the discussion, a few references are adde

Spectral representation and QCD sum rules for nucleon at finite temperature

We examine the problem of constructing spectral representations for two point correlation functions, needed to write down the QCD sum rules in the medium. We suggest constructing them from the Feynman diagrams for the correlation functions. As an example we use this procedure to write the QCD sum rules for the nucleon current at finite temperature

The type numbers of closed geodesics

A short survey on the type numbers of closed geodesics, on applications of the Morse theory to proving the existence of closed geodesics and on the recent progress in applying variational methods to the periodic problem for Finsler and magnetic geodesicsComment: 29 pages, an appendix to the Russian translation of "The calculus of variations in the large" by M. Mors