Nuclear Attenuation of high energy two-hadron system in the string model

Nuclear attenuation of the two-hadron system is considered in the string model. The two-scale model and its improved version with two different choices of constituent formation time and sets of parameters obtained earlier for the single hadron attenuation, are used to describe available experimental data for the $z$-dependence of subleading hadron, whereas satisfactory agreement with the experimental data has been observed. A model prediction for $\nu$-dependence of the nuclear attenuation of the two-hadron system is also presented.Comment: 8 page

Improved Crystal Method for Photon Beam Linear Polarization Measurement at High Energies

A method for photon linear polarization determination based on the measurement of the asymmetry of pairs produced by polarized photons in single crystals within the optimal intervals of pair particles energies is proposed. In difference to the well known methods the asymmetry in this case is essentially larger. The optimal orientation of crystal is found which provides the maximal values for analyzing power and figure of merit as well as minimal measurement time.Comment: 8 pages, 5 figure

New model for system of mesoscopic Josephson contacts

Quantum fluctuations of the phases of the order parameter in 2D arrays of mesoscopic Josephson junctions and their effect on the destruction of superconductivity in the system are investigated by means of a quantum-cosine model that is free of the incorrect application of the phase operator. The proposed model employs trigonometric phase operators and makes it possible to study arrays of small superconducting granules, pores filled with superfluid helium, or Josephson junctions in which the average number of particles $n_0$ (effective bosons, He atoms, and so on) is small, and the standard approach employing the phase operator and the particle number operator as conjugate ones is inapplicable. There is a large difference in the phase diagrams between arrays of macroscopic and mesoscopic objects for $n_0 < 5$ and $U<J$ ($U$ is the characteristic interaction energy of the particle per granule and $J$ is the Josephson coupling constant). Reentrant superconductivity phenomena are discussed.Comment: 4 pages, 3 Postscript figure

Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets

A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously

Nuclear Hadronization: Within or Without?

Nuclei are unique analyzers for the early stage of the space-time development of hadronization. DIS at medium energies is especially suitable for this task being sensitive to hadronization dynamics, since the production length is comparable with the nuclear size. This was the driving motivation to propose measurements at HERMES using nuclear targets, and to provide predictions based on a pQCD model of hadronization [1]. Now when the first results of the experiment are released [2,3], one can compare the predictions with the data. The model successfully describes with no adjustment the nuclear effects for various energies, zh, pT, and Q2, for different flavors and different nuclei. It turns out that the main source of nuclear suppression of the hadron production rate is attenuation of colorless pre-hadrons in the medium. An alternative model [4] is based upon an ad hoc assumption that the colorless pre-hadron is produced outside the nucleus. This model has apparent problems attempting to explain certain features of the results from HERMES. A good understanding of the hadronization dynamics is important for proper interpretation of the strong suppression of high-pT hadrons observed in heavy ion collisions at RHIC. We demonstrate that the production length is even shorter in this case and keeps contracting with rising pT.Comment: Latex 34 p. Based on talks given by B.Z.K. at the Fourth International Conference on Perspectives in Hadronic Physics, Trieste, Italy, May 12-16, 2003; and at the EuroConference on Hadron Structure Viewed with Electromagnetic Probes, Santorini, Greece, October 7-12, 200

ВЛИЯНИЕ ИЗМЕНЕНИЙ РОГОВОЙ ОБОЛОЧКИ ПРИ ПСЕВДОЭКСФОЛИАТИВНОМ СИНДРОМЕ НА СТЕПЕНЬ СОГЛАСИЯ МЕЖДУ ТОНОМЕТРОМ МАКЛАКОВА И ДИНАМИЧЕСКИМ КОНТУРНЫМ ТОНОМЕТРОМ PASCAL

Introduction. Pseudoexfoliative syndrome (PEX) changes the morphological structureof corneathat can affects its biomechanical properties. These properties affect the results of the intraocular pressure (IOP) measurement.Purpose of the study isto estimate the effect of PEХ on the error in intraocular pressure measurement (IOP) with Maklakov tonometer in relation to properties of the cornea.Materials and methods. The main group – 126 patients with PEХ, reference group – 104 patients without PEX. The main estimated indicator is the difference between the levels of IOP measured by the Maklakov tonometer and Pascaltonometer and coordination between two methods. Pascal tonometer was used as a reference one.Results and conclusions. The difference between the levels of IOP in the groups was unreliable. When measurements are made with Maklakov tonometer, PEX does not causethe significant tonometry error associated with properties of the cornea.Введение. При псевдоэксфолиативном синдроме (ПЭС) имеют место морфологические изменения роговой оболочки, которые могут влиять на ее биомеханические свойства. Последние, в свою очередь, влияют на результаты измерения внутриглазного давления (ВГД).Цель работы: оценка влияния ПЭС на ошибку измерения ВГД тонометром Маклакова, связанную со свойствами роговицы.Материал и методы. Основная группа – 126 пациентов с ПЭС, группа контроля – 104 пациента без ПЭС. Основной оценочный показатель – разница между уровнями ВГД, измеренного с помощью тонометра Маклакова и тонометром Pascal, а также степень их согласия. Тонометр Pascal – референтный тонометр.Результаты и выводы. Разница между уровнями ВГД в группах была недостоверна. ПЭС не вызывает значимой тонометрической ошибки, связанной со свойствами роговой оболочки, при использовании тонометра Маклакова

The HERMES Dual-Radiator Ring Imaging Cerenkov Detector

The construction and use of a dual radiator Ring Imaging Cerenkov(RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasizes measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses two radiators, C4F10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.Comment: 25 pages, 23 figure

Transverse-target-spin asymmetry in exclusive ω\omega-meson electroproduction

Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor.Comment: DESY Report 15-14

The Specificity of the Differential Regulation of Economic Integration in the Context of Contemporary Labor Migration

The issues of integration in the modern world become relevant in the rapidly changing geopolitical realities, and the strategic imperative of time for the vast majority of States. Today in accordance with the principle of multi-level and various-speed integration on Eurasian space are successfully developing various integration formats. They complement each other to provide a wide partnership platform. The authors argue that the main participants in labor migration in the post-Soviet space reflect the actual path of social and economic interaction worked out historically. Common historical fate and similar paths of development, similar mental conceptosphere steel trigger mechanism for the implementation of the Eurasian Economic Union. Researches show that labour of migrant workers from different countries is widely distributed in different sectors of Russia's economy, their labour is used almost everywhere. In many industries a mechanism was established where officially Russian workers are registered at enterprises, but foreign migrant workers are actually employed. Russians began to actively move, migration processes have increased substantially, new forms of temporary migration. These processes have become more active throughout Eurasia. The authors analyze the causes and characteristics of migration in the Eurasian economic union at the present stage. DOI: 10.5901/mjss.2015.v6n3p9