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Yerevan, Armenia

Chilingarian A.,Yerevan Physics Institute
Journal of Atmospheric and Solar-Terrestrial Physics

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. Source

Poghossian R.,Yerevan Physics Institute
Journal of High Energy Physics

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). Source

Oganesyan K.B.,Yerevan Physics Institute
Journal of Modern Optics

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. Source

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. Source

Poghossian R.,Yerevan Physics Institute
Journal of High Energy Physics

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

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