The probability distribution of the number of electron-positron pairs produced in a uniform electric field

The probability-generating function of the number of electron-positron pairs produced in a uniform electric field is constructed. The mean and variance of the numbers of pairs are calculated, and analytical expressions for the probability of low numbers of electron-positron pairs are given. A recursive formula is derived for evaluating the probability of any number of pairs. In electric fields of supercritical strength |eE| > \pi m^2/ \ln 2, where e is the electron charge, E is the electric field, and m is the electron mass, a branch-point singularity of the probability-generating function penetrates the unit circle |z| = 1, which leads to the asymptotic divergence of the cumulative probability. This divergence indicates a failure of the continuum limit approximation. In the continuum limit and for any field strength, the positive definiteness of the probability is violated in the tail of the distribution. Analyticity, convergence, and positive definiteness are restored upon the summation over discrete levels of electrons in the normalization volume. Numerical examples illustrating the field strength dependence of the asymptotic behavior of the probability distribution are presented.Comment: 7 pages, REVTeX, 4 figures; new references added; a short version of this e-print has appeared in PR

Strong light-matter coupling: parametric interactions in a cavity and free-space

We consider parametric interactions of laser pulses in a coherent macroscopic ensemble of resonant atoms, which are possible in the strong coupling regime of light-matter interaction. The spectrum condensation (lasing at collective vacuum Rabi sidebands) was studied in an active cavity configuration. Parametric interactions under the strong light-matter coupling were proved even in free space. In contrast to bichromatic beats in a cavity, they were shown to appear due to interference between polaritonic wave packets of different group velocities.Comment: 4 pages, 2 figure

Classical and relativistic dynamics of supersolids: variational principle

We present a phenomenological Lagrangian and Poisson brackets for obtaining nondissipative hydrodynamic theory of supersolids. A Lagrangian is constructed on the basis of unification of the principles of non-equilibrium thermodynamics and classical field theory. The Poisson brackets, governing the dynamics of supersolids, are uniquely determined by the invariance requirement of the kinematic part of the found Lagrangian. The generalization of Lagrangian is discussed to include the dynamics of vortices. The obtained equations of motion do not account for any dynamic symmetry associated with Galilean or Lorentz invariance. They can be reduced to the original Andreev-Lifshitz equations if to require Galilean invariance. We also present a relativistic-invariant supersolid hydrodynamics, which might be useful in astrophysical applications.Comment: 22 pages, changed title and content, added reference

Directed Polymer -- Directed Percolation Transition

We study the relation between the directed polymer and the directed percolation models, for the case of a disordered energy landscape where the energies are taken from bimodal distribution. We find that at the critical concentration of the directed percolation, the directed polymer undergoes a transition from the directed polymer universality class to the directed percolation universality class. We also find that directed percolation clusters affect the characterisrics of the directed polymer below the critical concentration.Comment: LaTeX 2e; 12 pages, 5 figures; in press, will be published in Europhys. Let

Universal Torsion-Induced Interaction from Large Extra Dimensions

We consider the Kaluza-Klein (KK) scenario in which only gravity exists in the bulk. Without the assumption of symmetric connection, the presence of brane fermions induces torsion. The result is a universal axial contact interaction that dominates those induced by KK gravitons. This enhancement arises from a large spin density on the brane. Using a global fit to Z-pole observables, we find the 3 sigma bound on the scale of quantum gravity to be 28 TeV for n=2. If Dirac or light sterile neutrinos are present, the data from SN1987A increase the bound to \sqrt{n}M_S >= 210 TeV.Comment: 9 pages REVTeX, 1 postscript figure, uses axodraw.st

Оценка влияния интеллектуального капитала вузов на интеллектуальный капитал регионов их локации

The paper presents the study’s results, which allow to reveal the role and importance of universities’ intellectual capital in the formation of a comprehensive assessment of the indicators of regional intellectual capital.Based on the study of theoretical materials and methods on the problems of intellectual capital of universities and regions, systems of indicators of their evaluation were composed. Hypotheses about the mutual influence of the intellectual capital of the region and universities, as well as their individual elements were put forward.As a result of hypothesis testing, based on the results of correlation-regression analysis, hypotheses about the influence of the universities’ intellectual capital as well as their individual elements (human and reputational capital) on the regions’ intellectual capital, as well as the influence of the universities’ intellectual capital on regions’ human capital were confirmed with an above-average level.El documento presenta los resultados del estudio, que permiten revelar el papel y la importancia del capital intelectual de las universidades en la formación de una evaluación integral de los indicadores del capital intelectual regional.Sobre la base del estudio de los materiales y métodos teóricos sobre los problemas del capital intelectual de las universidades y regiones, se compusieron sistemas de indicadores de su evaluación. Se expusieron hipótesis sobre la influencia mutua del capital intelectual de la región y las universidades, así como sus elementos individuales.Como resultado de la prueba de hipótesis, basada en los resultados del análisis de correlación-regresión, las hipótesis sobre la influencia del capital intelectual de las universidades y sus elementos individuales (capital humano y reputacional) en el capital intelectual de las regiones, así como en La influencia del capital intelectual de las universidades en el capital humano de las regiones se confirmó con un nivel superior al promedio.O artigo apresenta os resultados do estudo, que permitem revelar o papel e a importância do capital intelectual das universidades na formação de uma avaliação abrangente dos indicadores do capital intelectual regional.Com base no estudo de materiais e métodos teóricos sobre os problemas de capital intelectual de universidades e regiões, foram constituídos sistemas de indicadores de sua avaliação. Hipóteses sobre a influência mútua do capital intelectual da região e das universidades, bem como seus elementos individuais foram apresentadas.Como resultado do teste de hipóteses, baseado nos resultados da análise de correlação-regressão, hipóteses sobre a influência do capital intelectual das universidades, bem como seus elementos individuais (capital humano e reputacional) sobre o capital intelectual das regiões, bem como a A influência do capital intelectual das universidades sobre o capital humano das regiões foi confirmada com um nível acima da média.В работе представлены результаты исследования, которые позволяют выявить роль и значение интеллектуального капитала вузов в формировании комплексной оценки показателей регионального интеллектуального капитала.На основе изучения теоретических материалов и методов по проблематике интеллектуального капитала университетов и регионов были выделены системы показателей их оценки. Были выдвинуты гипотезы о взаимном влиянии интеллектуального капитала региона и вузов, а также их отдельных элементов.В результате проверки гипотез на основании обработки результатов корреляционно-регрессионного анализа были подтверждены гипотезы с уровнем выше среднего о наличии влияния интеллектуального капитала вузов, а также отдельных их элементов (человеческого и репутационного капитала) на интеллектуальный капитал регионов, а также интеллектуального капитала вузов на человеческий капитал регионов

Nutritional correction of cognitive impairment in patients with signs of premature aging

This paper deals with the questions of cognitive impairment in patients with signs of premature aging. Within the framework of this paper, it is shown that patients with a "negative" variant of the biological age have lower cognitive abilities than those with a "positive" variant of biological age. It is determined that nutritional support in patients with a "negative" variant of biological age ensures almost the same scores in the evaluation of cognitive functions, as in patients with a "positive" version of biological ag