The Uehling correction to the energy levels in a pionic atom

We consider a correction to energy levels in a pionic atom induced by the Uehling potential, i.e., by a free electron vacuum-polarization loop. The calculation is performed for circular states (l=n-1). The result is obtained in a closed analytic form as a function of $Z\alpha$ and the pion-to-electron mass ratio. Certain asymptotics of the result are also presented

On the boundary value problem for the vibration and wave processes in two-dimensional environs

In the article research of the third boundary value problem for the two - dimensional equation of free membrane vibrations is presented. The solution of the original differential operator is found in the form of a combination of the linearly independent system of orthonormal eigenfunctions on the given interval. Using the spectral decomposition for sufficiently smooth function, one can obtain the exact analytical representation of the deflection function for investigated problem in two - dimensional environs. The deflection function characterizes a membrane deviation from the equilibrium position

On the solution of boundary value problems by the spectral element method

In spectral element method approximate solution of the original differential operator is found in the form of a combination of the linearly independent system of orthogonal functions on the unit interval. Using the spectral decomposition for sufficiently smooth functions, one can obtain an exponential rate of convergence of the approximate solution to the exact solution and the approximation error will decrease exponentially as n grows. In the article the application of spectral element method to the solution of the boundary value problem for the Poisson equation is presented

Thomson and Compton scattering with an intense laser pulse

Our paper concerns the scattering of intense laser radiation on free electrons and it is focused on the relation between nonlinear Compton and nonlinear Thomson scattering. The analysis is performed for a laser field modeled by an ideal pulse with a finite duration, a fixed direction of propagation and indefinitely extended in the plane perpendicular to it. We derive the classical limit of the quantum spectral and angular distribution of the emitted radiation, for an arbitrary polarization of the laser pulse. We also rederive our result directly, in the framework of classical electrodynamics, obtaining, at the same time, the distribution for the emitted radiation with a well defined polarization. The results reduce to those established by Krafft et al. [Phys. Rev. E 72, 056502 (2005)] in the particular case of linear polarization of the pulse, orthogonal to the initial electron momentum. Conditions in which the differences between classical and quantum results are visible are discussed and illustrated by graphs

New experimental data for the decays ϕ→μ+μ−\phi\to\mu^+\mu^- and ϕ→π+π−\phi\to\pi^+\pi^- from SND detector

The processes $e^+e^-\to\mu^+\mu^-$ and $e^+e^-\to\pi^+\pi^-$ have been studied with SND detector at VEPP-2M $e^+e^-$ collider in the vicinity of $\phi(1020)$ resonance. The branching ratios $B(\phi\to\mu^+\mu^-)=(3.30\pm 0.45\pm 0.32)\times 10^{-4}$ and $B(\phi\to\pi^+\pi^-)=(0.71\pm 0.11\pm 0.09)\times 10^{-4}$ were obtained.Comment: 5 pages, 4 figures, talk given at 8th International Conference on Hadron Spectroscopy (HADRON 99), Beijing, China, 24-28 Aug 199

Hunting For Massive Late-Type Stars In The Inner Disk Of The Milky Way

Stars and planetary system

Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.Comment: 14 pages, 8 figure

Analytic Methods in Nonperturbative QCD

Recently developed analytic methods in the framework of the Field Correlator Method are reviewed in this series of four lectures and results of calculations are compared to lattice data and experiment. Recent lattice data demonstrating the Casimir scaling of static quark interaction strongly support the FCM and leave very little space for all other theoretical models, e.g. instanton gas/liquid model. Results of calculations for mesons, baryons, quark-gluon plasma and phase transition temperature demonstrate that new analytic methods are a powerful tool of nonperturbative QCD along with lattice simulations.Comment: LaTeX, 34 pages; Lectures given at the 13th Indian-Summer School "Understanding the Structure of Hadrons", August 28 - September 1, 2000, Prague, Czech Republi

Precision Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetries A2

We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 0.7 < Q^2 < 20 GeV^2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets. Our measured g2 approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d2p and d2n are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x->0. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range. The absolute value of A2 is significantly smaller than the sqrt[R(1+A1)/2] limit.Comment: 12 pages, 4 figures, 2 table

The C-80 cyclotron system. Current status

The C-80 cyclotron system is intended to produce proton beams with an energy ranging from 40 up to 80 MeV and current up to 200 μA. The beams with the aforementioned parameters will be used for commercial production of a wide assortment of isotopes for medicine including radiation generators. In addition, creation of a special beamline to form homogeneous proton beams of ultra-low intensity (10⁷…10⁹) will allow the proton therapy of eye diseases and superficial oncological diseases as well as tests of radioelectronic components for radiation resistance to be performed. The equipment of the cyclotron and the first section of the beam transport system has been manufactured, tested at test facilities in the Efremov Institute, installed in the PNPI and made ready for acceptance tests.Циклотронный комплекс Ц-80 предназначен для получения протонных пучков с энергией 40…80 МэВ и током до 200 мкА. Пучки с такими параметрами будут использоваться для производства широкого спектра изотопов медицинского назначения, в том числе генераторов излучения, в коммерческих масштабах. Кроме того, создание специального тракта формирования гомогенных пучков протонов ультрамалой интенсивности (10⁷…10⁹) позволит осуществлять протонную лучевую терапию глаза и поверхностных форм онкологических заболеваний, а также проводить испытания радиоэлектронных изделий на радиационную стойкость. Оборудование циклотрона и первого участка системы транспортировки изготовлено и испытано на стендах НИИЭФА им. Д.В. Ефремова, смонтировано в ПИЯФ им. Б.П. Константинова и подготовлено для проведения приемосдаточных испытаний.Циклотронний комплекс Ц-80 призначений для отримання протонних пучків з енергією 40...80 МеВ і струмом до 200 мкА. Пучки з такими параметрами використовуватимуться для виробництва широкого спек-тра ізотопів медичного призначення, у тому числі генераторів випромінювання, в комерційних масштабах. Крім того, створення спеціального тракту формування гомогенних пучків протонів ультрамалої інтенсивності (10⁷…10⁹) дозволить здійснювати протонну променеву терапію ока і поверхневих форм онкологічних захворювань, а також проводити випробування радіоелектронних виробів на радіаційну стійкість. Устаткування циклотрона і першої ділянки системи транспортування виготовлене та випробуване на стендах НДІЕФА ім. Д.В. Єфремова, змонтовано в ПІЯФ ім. Б.П. Константинова і підготовлено для проведення приймальноздавальних випробувань