Relativistic Dynamics of Vector Bosons in the Field of Gravitational Radiation

We consider a model of the state evolution of relativistic vector bosons, which includes both the dynamical equations for the particle four-velocity and the equations for the polarization four-vector evolution in the field of a nonlinear plane gravitational wave. In addition to the gravitational minimal coupling, tidal forces linear in curvature tensor are suggested to drive the particle state evolution. The exact solutions of the evolutionary equations are obtained. Birefringence and tidal deviations from the geodesic motion are discussed.Comment: 10 pages, no figures, Te

Archimedean-type force in a cosmic dark fluid: II. Qualitative and numerical study of a multistage Universe expansion

In this (second) part of the work we present the results of numerical and qualitative analysis, based on a new model of the Archimedean-type interaction between dark matter and dark energy. The Archimedean-type force is linear in the four-gradient of the dark energy pressure and plays a role of self-regulator of the energy redistribution in a cosmic dark fluid. Because of the Archimedean-type interaction the cosmological evolution is shown to have a multistage character. Depending on the choice of the values of the model guiding parameters,the Universe's expansion is shown to be perpetually accelerated, periodic or quasiperiodic with finite number of deceleration/acceleration epochs. We distinguished the models, which can be definitely characterized by the inflation in the early Universe, by the late-time accelerated expansion and nonsingular behavior in intermediate epochs, and classified them with respect to a number of transition points. Transition points appear, when the acceleration parameter changes the sign, providing the natural partition of the Universe's history into epochs of accelerated and decelerated expansion. The strategy and results of numerical calculations are advocated by the qualitative analysis of the instantaneous phase portraits of the dynamic system associated with the key equation for the dark energy pressure evolution.Comment: 15 pages, 12 figures, Part II, typos corrected, Fig.4 replaced, references correcte

Assessment of the level and structure of stress in tax revenues of the federal and regional budgets

Relevance. In recent years, the Russian economy has faced the global challenges posed by the COVID-19 pandemic and unprecedented sanctions. Understanding how the tax systems of Russian regions respond to these external shocks is crucial for identifying critical stress sources affecting budgets at various levels.Research objective. This study aims to assess and compare tax revenue stress across the federal districts of the Russian Federation, considering different levels of the budget system, and to identify the underlying sources of this stress.Data and methods. The study relies on official data from the Federal Tax Service of the Russian Federation on tax revenues to federal and regional budgets in the federal districts. The analysis covers monthly data from January 2013 to December 2022. The stress index was calculated by measuring the difference between the moving standard deviation and the mean of the annual tax revenue growth rate, with a lag of 1 month. The methodology for decomposing the sources of tax revenue stress was also tested.Results. Over-time assessments of stress indices for tax revenues to federal and regional budgets were obtained for the Russian Federation and its federal districts. The varying levels, dynamics, and budgetary distribution of tax revenue stress across federal districts are explained by differences in the structure, growth rates, and volatility of various taxes, as well as their correlations in these districts. Decomposition of federal and regional tax stress showed the unique role of mineral extraction tax and profit tax as stress amplifiers during crises, while in stable periods, they contribute significantly to stress reduction. The study also establishes the distinct roles of federal districts in intensifying or alleviating overall tax revenue stress during pandemic and sanctions shocks, as well as periods of relative stability.Conclusions. This research demonstrates the importance of assessing and identifying sources of tax revenue stress in regions. Such insights help identify vulnerabilities and reserves for enhancing the resilience of regional and federal budgets through the diversification of regional economic systems and adjustments to tax system rules in response to changing external conditions

Non-minimal electrodynamics and resonance interactions in relativistic plasma

A three-parameter toy-model, which describes a non-minimal coupling of gravity field with electromagnetic field of a relativistic two-component electrically neutral plasma, is discussed. Resonance interactions between particles and transversal waves in plasma are shown to take place due to the curvature coupling effect.Comment: 6 pages, no figures, the short version of the talk at RUSGRAV-13, to be published in Gravitation and Cosmology, 2009, No.

Cherenkov radiation in a gravitational wave background

A covariant criterion for the Cherenkov radiation emission in the field of a non-linear gravitational wave is considered in the framework of exact integrable models of particle dynamics and electromagnetic wave propagation. It is shown that vacuum interacting with curvature can give rise to Cherenkov radiation. The conically shaped spatial distribution of radiation is derived and its basic properties are discussed.Comment: LaTeX file, no figures, 19 page

Non-minimal coupling of photons and axions

We establish a new self-consistent system of equations accounting for a non-minimal interaction of gravitational, electromagnetic and axion fields. The procedure is based on a non-minimal extension of the standard Einstein-Maxwell-axion action. The general properties of a ten-parameter family of non-minimal linear models are discussed. We apply this theory to the models with pp-wave symmetry and consider propagation of electromagnetic waves non-minimally coupled to the gravitational and axion fields. We focus on exact solutions of electrodynamic equations, which describe quasi-minimal and non-minimal optical activity induced by the axion field. We also discuss empirical constraints on coupling parameters from astrophysical birefringence and polarization rotation observations.Comment: 31 pages, 2 Tables; replaced with the final version published in Classical and Quantum Gravit