Yerevan, Armenia
Yerevan, Armenia

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Agency: European Commission | Branch: FP7 | Program: | Phase: | Award Amount: 3.21M | Year: 2008

eInfrastructure in Europe has reached a mature state where the GEANT network forms a backbone on top of which a distributed computing infrastructure - the Grid - provides processing and storage services for eScience research. The South-East European eInfrastructure initiatives are committed to ensuring equal participation of the less-resourced countries of the region in European trends. SEEREN initiative has established a regional network and its GEANT connection and the SEE-GRID initiative the regional Grid. Hereby proposed SEE-GRID-SCI will leverage the SEE eInfrastructure to enable new scientific collaborations among SEE user communities. SEE-GRID-SCI will stimulate widespread integrated eInfrastructure uptake by new cross-border user groups extending over the region, fostering collaboration and providing advanced capabilities to more researchers, with an emphasis on strategic groups in seismology, meteorology and environmental protection. The initiative thus aims to have a catalytic and structuring effect on a variety of user communities that currently do not directly benefit from the available eInfrastructures. In parallel, it will enlarge the regional eInfrastructure to cater for demands of the communities: a number of new Grid clusters and countries will be added, engaging a wider range of players and expanding the provider pool. Finally, SEE-GRID-SCI will help mature and stabilise the National Grid Initiatives in the region, allowing them to join the new era of longer-term sustainable Grid infrastructure in Europe. In this context, SEE-GRID-SCI will aim to attract political and financial support for materializing the eInfrastructure vision. In longer term, SEE-GRID-SCI aspires to contribute to the stabilisation and development of South-East Europe, by easing the digital divide and stimulating eInfrastructure development and adoption by new user communities, thus enabling collaborative high-quality research across a spectrum of scientific fields.

Chilingarian A.,Yerevan Physics Institute
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2014

In the beginning of last century C.T.R. Wilson proposed that strong electric field of the thunderclouds might accelerate electrons to very high energies. However, this and many other electromagnetic processes in our atmosphere are poorly understood till now; the key questions about the thundercloud electrification and lightning initiation remain unanswered. During recent decades several observations of gamma ray, electron and neutron fluxes correlated with thunderstorms were reported. Nonetheless, the origin of these fluxes is under debate till now. The direct registration of the particle showers initiated by the runaway electrons (the most popular theory) was missing. We present the experimental evidence of the microsecond duration electron bursts originated from runaway electrons accelerated in thunderclouds. The electron acceleration downward becomes possible after creation of the Lower Positive Charged Region below the main negative charged layer in the middle of the thundercloud. Our analysis is based on the vast thunderstorm data from the Aragats Mountain in Armenia, 3200. m above sea level. Varieties of particle detectors located at Aragats Space Environmental Center are registering neutral and charged particle fluxes correlated with thunderstorms, so-called Thunderstorm Ground Enhancements. Simultaneously the electric mills and lightning detectors are monitoring the near-surface electric field and lightning flashes. In the paper we present the model of TGE initiation. We demonstrate the necessity of the Lower positive charge region development for the lower dipole operation and TGE initiation. Our observations establish direct relationship of the negative electric field strength and rain rate with TGE. © 2013 Elsevier Ltd.

Poghossian R.,Yerevan Physics Institute
Journal of High Energy Physics | Year: 2014

Zamolodchikov's famous analysis of the RG trajectory connecting successive minimal CFT models M p and M p-1 for p â‰. © The Authors.

Oganesyan K.B.,Yerevan Physics Institute
Journal of Modern Optics | Year: 2014

A relativistic electron motion in a transversally inhomogeneous magnetic field of a wiggler is shown to consist of fast (undulator) and slow (strophotron) components. By separating fast and slow motions and by averaging equations of motion over fast undulator oscillations, we find spectral intensity of strophotron spontaneous emission in such a system. The strophotron intensity of spontaneous emission is shown to be well separated spectrally from the usual undulator parts. © 2014 Taylor & Francis.

Khachatryan S.,Yerevan Physics Institute
Nuclear Physics B | Year: 2014

A unified approach is applied in the consideration of the multi-parametric (colored) Yang-Baxter equations (YBE) and the usual YBE with two-parametric R-matrices, relying on the existence of the arbitrary functions in the general solutions. The colored YBE are considered with the R-matrices defined on two and three-dimensional states. We present an exhaustive study and the overall solutions for the YBE with 4×4 colored R-matrices. The established classification includes new multi-parametric free fermionic solutions. In the context of the given approach there are obtained the colored solutions to the YBE with 9 × 9 R-matrices having 15 non-zero elements. © 2014 The Author.

Oganesyan K.B.,Yerevan Physics Institute
Journal of Modern Optics | Year: 2014

We calculate the gain in a plane wiggler (undulator) with inhomogeneous magnetic field and in the external electromagnetic wave. The electromagnetic field-induced corrections to electron trajectories are found. The linear (field-independent) gain is calculated using these corrections to complex motion of electrons, which was described in previous paper, without electromagnetic field. This complex motion arises because of magnetic field inhomogeneity. It is shown that the account of inhomogeneity of the magnetic field leads to appearance of additional peaks in the gain of usual wiggler with uniform magnetic field. © 2014 © 2014 Taylor & Francis.

Poghossian R.,Yerevan Physics Institute
Journal of High Energy Physics | Year: 2016

Abstract: It is shown that the deformed Seiberg-Witten curve equation after Fourier transform is mapped into a differential equation for the AGT dual 2d CFT cnformal block containing an extra completely degenerate field. We carefully match parameters in two sides of duality thus providing not only a simple independent prove of the AGT correspondence in Nekrasov-Shatashvili limit, but also an extension of AGT to the case when a secondary field is included in the CFT conformal block. Implications of our results in the study of monodromy problems for a large class of n’th order Fuchsian differential equations are discussed. © 2016, The Author(s).

Karapetyan G.G.,Yerevan Physics Institute
Astroparticle Physics | Year: 2012

We conducted theoretical investigation of long lasting pulses of cosmic-ray electrons and gamma-ray radiation, which are often observed during thunderstorms by particle detectors at high altitude cosmic-ray stations. These thunderstorm ground enhancements (TGEs) last several minutes, during which the flux of electrons and gamma-quants can surpass a few hundred percent over background level. We developed theoretical model and derived energetic spectrums of electrons and gamma-quants at given value of thunderstorm electric field. The model considers two following mechanisms, which can change the flux of electrons in electric field: (i) transformation of the spectrum of cosmic-ray electrons and (ii) formation of electron avalanche. Due to (i) the number of low (few MeV) energy electrons decreases and small abundance (<5% of total flux of cosmic rays) of cosmic-ray electrons with energies >10 MeV emerges. The spectral fluxes of two electron components - avalanche and cosmic-ray electrons are derived, which shows that contribution of cosmic-ray electrons in total abundance of electrons is small. Consequently, the contribution of gamma ray radiation, produced by the abundance of cosmic-ray electrons is small as well. We derived the exact equations for the spectrums of these two components of gamma ray radiation and showed that spectral curve of avalanche gamma-quants can be approximated by a simple function exp(-E/E 0)/E up to ∼40 MeV. At higher energies gamma-ray radiation is produced by the abundance of cosmic-ray electrons and it has approximately power-law spectrum. © 2012 Elsevier B.V. All rights reserved.

Allahverdyan A.E.,Yerevan Physics Institute
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The concept of work is basic for statistical thermodynamics. To gain a fuller understanding of work and its (quantum) features, it needs to be represented as an average of a fluctuating quantity. Here I focus on the work done between two moments of time for a thermally isolated quantum system driven by a time-dependent Hamiltonian. I formulate two natural conditions needed for the fluctuating work to be physically meaningful for a system that starts its evolution from a nonequilibrium state. The existing definitions do not satisfy these conditions due to issues that are traced back to noncommutativity. I propose a definition of fluctuating work that is free of previous drawbacks and that applies for a wide class of nonequilibrium initial states. It allows the deduction of a generalized work-fluctuation theorem that applies for an arbitrary (out-of-equilibrium) initial state. © 2014 American Physical Society.

Mkrtchyan R.L.,Yerevan Physics Institute
Journal of High Energy Physics | Year: 2013

Closed simple integral representation through Vogel's universal parameters is found both for perturbative and nonperturbative (which is inverse invariant group volume) parts of free energy of Chern-Simons theory on S 3. This proves the universality of that partition function. For classical groups it manifestly satisfy N → -N duality, in apparent contradiction with previously used ones. For SU(N) we show that asymptotic of nonperturbative part of our partition function coincides with that of Barnes G-function, recover Chern-Simons/topological string duality in genus expansion and resolve abovementioned contradiction. We discuss few possible directions of development of these results: derivation of representation of free energy through Gopakumar-Vafa invariants, possible appearance of non-perturbative additional terms, 1/N expansion for exceptional groups, duality between string coupling constant and Kähler parameters, etc. © 2013 SISSA, Trieste, Italy.

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