Microscopic derivation of the pion coupling to heavy-light mesons

The Goldberger--Treiman relation for heavy--light systems is derived in the context of a quark model. As a paradigmatic example, the case of ${\bar D}\to {\bar D}' \pi$ is studied in detail. The fundamental role played by the pion two-component wave function, in the context of the Salpeter equation, is emphasized.Comment: 6 pages, 2 figures, version to appear in Phys. Rev.

On Goldstone bosons decoupling from high-lying hadrons

In this paper, we discuss a decoupling of the Goldstone bosons from highly excited hadrons in relation to the restoration of chiral symmetry in such hadrons. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of an instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. For highly excited hadrons, where the typical momentum of valence quarks is large, the loop contributions represent only a small correction to the chiral-invariant classical contributions and asymptotically vanish. Consequently the chiral symmetry violating Lorentz-scalar dynamical mass of quarks vanishes. Then the conservation of the axial vector current in the chiral limit requires, via the Goldberger-Treiman relation, that the valence quarks decouple from the Goldstone boson. As a consequence, the whole hadron decouples from the Goldstone boson as well, which implies that its axial constant also vanishes.Comment: RevTeX4, 21 pages, 5 Postscript figures, uses epsfig.sty, new chapter with numerical estimates added, to appear in Phys.Rev.

Chiral symmetry restoration in excited hadrons, quantum fluctuations, and quasiclassics

In this paper, we discuss the transition to the semiclassical regime in excited hadrons, and consequently, the restoration of chiral symmetry for these states. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of the instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. It has been shown recently that the effective single-quark potential is of the Lorentz-scalar nature, for the low-lying hadrons, while, for the high-lying states, it becomes a pure Lorentz vector and hence the model exhibits the restoration of chiral symmetry. We demonstrate explicitly the quantum nature of chiral symmetry breaking, the absence of chiral symmetry breaking in the classical limit as well as the transition to the semiclassical regime for excited states, where the effect of chiral symmetry breaking becomes only a small correction to the classical contributions.Comment: RevTeX4, 20 pages, 4 Postscript figures, uses epsfig.sty, typos correcte

Education in the system of today’s employee values

Establishing the new society is accompanied by a global intellectualization of the entire economic system influencing the development of information, scientific and innovative branches of the indusry. The key factors of the society develpment are information and knowledge. An important quality of a modern employee is the ability for continuous training. Currently, the interest to education has significantly increased as well as the demand for education and the educational level of employees. Education is one of the most vital values, meeting the natural needs of humans in the knowledge of the external world and themselves. The growth of social demand for education in the evolution of social development has led to the gradual transformation of the elite educational institutions into the institutions for everyone. For most people nowadays, higher education has become not only sustainable, but one of the most significant values. The successful development of knowledge-based economy could be provided by the employees not only having a high degree, but having a desire for the continuous lifelong knowledge development

QCD string in light-light and heavy-light mesons

The spectra of light-light and heavy-light mesons are calculated within the framework of the QCD string model, which is derived from QCD in the Wilson loop approach. Special attention is payed to the proper string dynamics that allows us to reproduce the straight-line Regge trajectories with the inverse slope being 2\pi\sigma for light-light and twice as small for heavy-light mesons. We use the model of the rotating QCD string with quarks at the ends to calculate the masses of several light-light mesons lying on the lowest Regge trajectories and compare them with the experimental data as well as with the predictions of other models. The masses of several low-lying orbitally and radially excited heavy--light states in the D, D_s, B, and B_s meson spectra are calculated in the einbein (auxiliary) field approach, which has proven to be rather accurate in various calculations for relativistic systems. The results for the spectra are compared with the experimental and recent lattice data. It is demonstrated that an account of the proper string dynamics encoded in the so-called string correction to the interquark interaction leads to an extra negative contribution to the masses of orbitally excited states that resolves the problem of the identification of the D(2637) state recently claimed by the DELPHI Collaboration. For the heavy-light system we extract the constants \bar\Lambda, \lambda_1, and \lambda_2 used in Heavy Quark Effective Theory (HQET) and find good agreement with the results of other approaches.Comment: RevTeX, 42 pages, 7 tables, 7 EPS figures, uses epsfig.sty, typos corrected, to appear in Phys.Rev.

Radiative Decays of Excited Vector Mesons

Radiative decays of the $1^3S_1$ radial and $1^3D_1$ orbital excitations of the $\rho$, $\omega$ and $\phi$ are calculated in the quark model, using wave functions obtained variationally from the Hamiltonian with standard quark-model parameters. The larger radiative widths should be measurable at new high-intensity facilities being proposed, and in some cases may be measurable in data from existing experiments. The radiative decays are a strong discriminator between the $1^3S_1$ and $1^3D_1$ excitations, and can also be used to provide unique information about the decay products.Comment: 23 pages, 6 figure

Application of magnetic nanoparticles, fluorescent nanoparticles and nanozymes in immunoassays

The reported study was funded by RFBR according to the research project № 19-015-00408 А

Functional integration of brain regions in children with speech disorders from the positions of sexual dimorphism and interhemispheric functional asymmetry

The aim of the study was to study the features of the functional integration of brain zones, taking into account the functional dominance of the hemispheres and sexual dimorphism in the process of prospective observation.В статье рассматриваются особенности функциональной интеграции зон мозга с учетом функциональной доминантности полушарий и полового диморфизма в процессе проспективного наблюдения

Decay constants of the heavy-light mesons from the field correlator method

Meson Green's functions and decay constants $f_{\Gamma}$ in different channels $\Gamma$ are calculated using the Field Correlator Method. Both, spectrum and $f_\Gamma$, appear to be expressed only through universal constants: the string tension $\sigma$, $\alpha_s$, and the pole quark masses. For the $S$-wave states the calculated masses agree with the experimental numbers within $\pm 5$ MeV. For the $D$ and $D_s$ mesons the values of $f_{\rm P} (1S)$ are equal to 210(10) and 260(10) MeV, respectively, and their ratio $f_{D_s}/f_D$=1.24(3) agrees with recent CLEO experiment. The values $f_{\rm P}(1S)=182, 216, 438$ MeV are obtained for the $B$, $B_s$, and $B_c$ mesons with the ratio $f_{B_s}/f_B$=1.19(2) and $f_D/f_B$=1.14(2). The decay constants $f_{\rm P}(2S)$ for the first radial excitations as well as the decay constants $f_{\rm V}(1S)$ in the vector channel are also calculated. The difference of about 20% between $f_{D_s}$ and $f_D$, $f_{B_s}$ and $f_B$ directly follows from our analytical formulas.Comment: 37 pages, 10 tables, RevTeX

Clinical specificity of sleep disorders in children with deviant development

В статье рассматриваются клинические особенности сна у детей дошкольного возраста с синдромом дефицита внимания и гиперактивности.The article describes specific clinical features of sleep in preschool children with attention deficit hyper¬activity disorder (ADHD) and motor developmental dysphasia (MDD)