1,652 research outputs found
Neutrino propagation in media and axis of complete polarization
We construct a spectral representation of neutrino propagator in moving
matter or in external magnetic field. In both cases there exists fixed
four-dimensional axis of polarization, such that the corresponding spin
projectors commute with propagator. As a result, all eigenvalues of propagator
and, consequently, dispersion laws for neutrino in media are classified
according to spin projection onto this axis. Use of the found spin projectors
simplifies essentially the eigenvalue problem and allows to build spectral
representation of propagator in moving matter or external magnetic field in
analogy with the vacuum propagator.Comment: 16 pages, journal versio
Decision Support System for Urbanization of the Northern Part of the Volga-Akhtuba Floodplain (Russia) on the Basis of Interdisciplinary Computer Modeling
There is a computer decision support system (CDSS) for urbanization of the
northern part of the Volga-Akhtuba floodplain. This system includes subsystems
of cognitive and game-theoretic analysis, geoinformation and hydrodynamic
simulations. The paper presents the cognitive graph, two-level and three-level
models of hierarchical games for the cases of uncontrolled and controlled
development of the problem situation. We described the quantitative analysis of
the effects of different strategies for the spatial distribution of the
urbanized territories. For this reason we conducted the territory zoning
according to the level of negative consequences of urbanization for various
agents. In addition, we found an analytical solution for games with the linear
dependence of the average flooded area on the urbanized area. We numerically
computed a game equilibrium for dependences derived from the imitational
geoinformation and hydrodynamic modeling of flooding. As the result, we showed
that the transition to the three-level management system and the implementation
of an optimal urbanization strategy minimize its negative consequences.Comment: 14 pages, 5 figures; Conference: Creativity in Intelligent
Technologies and Data Science. CIT&DS 201
Geomagnetic disturbances on ground associated with particle precipitation during SC
We have examined several cases of magnetosphere compression by solar wind pressure pulses using a set of instruments located in the noon sector of auroral zone. We have found that the increase in riometric absorption (sudden commencement absorption, SCA) occurred simultaneously with the beginning of negative or positive magnetic variations and broadband enhancement of magnetic activity in the frequency range above 0.1 Hz. Since magnetic variations were observed before the step-like increase of magnetic field at equatorial station (main impulse, MI), the negative declinations resembled the so-called preliminary impulse, PI. In this paper a mechanism for the generation of PI is introduced whereby PI's generation is linked to SCA – associated precipitation and the local enhancement of ionospheric conductivity leading to the reconstruction of the ionospheric current system prior to MI. Calculation showed that PI polarity depends on orientation of the background electric field and location of the observation point relative to ionospheric irregularity. For one case of direct measurements of electric field in the place where the ionospheric irregularity was present, the sign of calculated disturbance corresponded to the observed one. High-resolution measurements on IRIS facility and meridional chain of the induction magnetometers are utilized for the accurate timing of the impact of solar wind irregularity on the magnetopause
Can we observe the gravitational quantum states of Positronium?
In this paper we consider the feasibility of observing the gravitational
quantum states of positronium. The proposed scheme employs the flow-throw
technique used for the first observation of this effect with neutrons.
Collimation and Stark deceleration of Rydberg positronium atoms allow to select
the required velocity class. If this experiment could be realized with
positronium it would lead to a determination of g for this matter-antimatter
system at the few % level. As discussed in this contribution, most of the
required techniques are currently available but important milestones have to be
demonstrated experimentally before such an experiment could become reality.
Those are: the efficient focusing of a bunched positron beam, Stark
deceleration of Rydberg positronium and its subsequent excitation into states
with large angular momentum. We provide an estimate of the efficiencies we
expect for these steps and assuming those could be confirmed we calculate the
signal rate.Comment: 12 pages, 1 figure, contribution to the GRANIT 2014 workshop: Quantum
gravitationnal spectroscopy with ultra-cold system
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