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S. Belov

Publications and source records attributed to S. Belov.

10 recordsLinked to original sources
arXiv2026

Failed ejection and oscillations of a current-carrying filament balanced by gravity

In this study, we investigate the post-destabilization evolution of a filament in a gravity-balanced model. We adopt the filament model proposed by Solov'ev (2010), in which a dense filament is supported against gravity by the repulsive force between the filament current and its sub-photospheric image. We first performed an analytical investigation of this model. For the numerical study, we use a two-dimensional magnetohydrodynamic (MHD) model that solves the MHD equations with the Lare2d numerical code. Results: In this filament model, analytical expressions are derived for the electric current density, plasma density, and their spatial distributions as functions of the model parameters. The total electric current and the filament weight are also calculated. For the numerical simulations, we constructed an equilibrium filament characterized by a magnetic field of $B_0$ = $10^{-3}$ T, mass density $ρ_0$ ~ 1.3 x $10^{-9}$ kg m$^{-3}$, and temperature T ~ 13000 K. The system was destabilized either by increasing the currents or by reducing the filament density, and its evolution was computed. In both destabilization regimes, the filament was ejected, then halted at a certain altitude, and subsequently fell back, repeating this cycle with a period of about 600 s. The maximum filament ejection velocity was approximately 80 and 40 km $s^{-1}$, respectively. Beneath the ejected filament a current sheet forms, where magnetic reconnection occurs. The maximum ejection altitudes were determined as functions of both the destabilizing currents and the degree of filament plasma dilution. Finally, we compared results of this MHD model with those of an ideal vacuum model and discussed all results.

astro-ph.SR↗
arXiv2025

Thermodynamic Evolution of Flaring Loops with Non-local Thermal Transport

Hot solar coronal loops, such as flaring loops, reach temperatures where the thermal transport becomes non-local. This occurs when the mean-free-path of electrons can no longer be assumed to be small. Using a modified version of the Lare2d code, we study the evolution of flare-heated coronal loops under three thermal transport models: classical Spitzer-Harm (SH), a flux-limited local model (FL), and the non-local Schurtz-Nicolai-Basquet (SNB) model. The SNB model is used extensively in laser-plasma studies. It has been benchmarked against accurate non-local Vlasov-Fokker-Planck models and proven to be the most accurate non-local model which can be applied on fluid time-scales. Analysis of the density-temperature evolution cycles near the loop apex reveals a distinct evolutionary path for the SNB model, with higher temperatures and lower densities than local models. During energy deposition, the SNB model produces a more localised and intense temperature peak at the apex due to heat flux suppression, which also reduces chromospheric evaporation and results in lower post-flare densities. EUV emission synthesis shows that the SNB model yields flare light curves with lower peak amplitudes and smoother decay phases. We also find that non-local transport affects equilibrium loop conditions, producing hotter and more rarefied apexes. These findings emphasise the need to account for non-local conduction in dynamic solar phenomena and highlight the potential of the SNB model for improving the realism of flare simulations. Flux-limited conduction models cannot reproduce the results of non-local transport covered by the SNB model.

astro-ph.SR↗
arXiv2021

Longitudinal Plasma Motions Generated by Shear Alfvén Waves in Plasma with Thermal Misbalance

Compressional plasma perturbations may cause thermal misbalance between plasma heating and cooling processes. This misbalance significantly affects the dispersion properties of compressional waves providing a feedback between the perturbations and plasmas. It has been shown that Alfvén waves may induce longitudinal (compressional) plasma motions. In the present study, we analyze the effects of thermal misbalance caused by longitudinal plasma motions induced by shear Alfvén waves. We show that thermal misbalance leads to appearance of exponential bulk flows, which itself modifies the Alfvén induced plasma motions. In the case of sinusoidal Alfvén waves, we show how the amplitude and phase shift of induced longitudinal motions gain dependence on the Alfvén wave frequency while shedding light on its functionality. This feature has been investigated analytically in application to coronal conditions. We also consider the evolution of longitudinal plasma motions induced by the shear sinusoidal Alfvén wave by numerical methods before comparing the results obtained with our presented analytical predictions to justify the model under consideration in the present study.

physics.plasm-ph↗
arXiv2015

Semi-relativistic wave-phase approximation for two-body spinless bound states in 1+1 dimensions

An approximate quantum-mechanical two-body equation for spinless particles incorporating relativistic kinematics is derived. The derivation is based on the relativistic energy-momentum relation $mc^{2}+ε= \sqrt{m^{2}c^{4}+p^{2}c^{2}}+V$ for each single particle, where $mc^2$ is the particle rest mass energy, $p$ its linear momentum, $ε$ its dynamical energy, and $V$ being the time-like vector interaction potential. The resulting two-body equation assumes rapid wave oscillations in a single, slowly varying potential well. A Bohr-Sommerfeld-type quantization condition is obtained. The approximation is compared to exact results for the harmonic potential.

quant-ph↗
arXiv2010

HepML, an XML-based format for describing simulated data in high energy physics

In this paper we describe a HepML format and a corresponding C++ library developed for keeping complete description of parton level events in a unified and flexible form. HepML tags contain enough information to understand what kind of physics the simulated events describe and how the events have been prepared. A HepML block can be included into event files in the LHEF format. The structure of the HepML block is described by means of several XML Schemas. The Schemas define necessary information for the HepML block and how this information should be located within the block. The library libhepml is a C++ library intended for parsing and serialization of HepML tags, and representing the HepML block in computer memory. The library is an API for external software. For example, Matrix Element Monte Carlo event generators can use the library for preparing and writing a header of a LHEF file in the form of HepML tags. In turn, Showering and Hadronization event generators can parse the HepML header and get the information in the form of C++ classes. libhepml can be used in C++, C, and Fortran programs. All necessary parts of HepML have been prepared and we present the project to the HEP community.

hep-ph↗
arXiv2009

Low temperature properties of the Electron Spin Resonance in YbRh2Si2

We present the field and temperature behavior of the narrow Electron Spin Resonance (ESR) response in YbRh2Si2 well below the single ion Kondo temperature. The ESR g factor reflects a Kondo-like field and temperature evolution of the Yb3+ magnetism. Measurements towards low temperatures (>0.5K) have shown distinct crossover anomalies of the ESR parameters upon approaching the regime of a well defined heavy Fermi liquid. Comparison with the field dependence of specific heat and electrical resistivity reveal that the ESR parameters can be related to quasiparticle mass and cross section and, hence, contain inherent heavy electron properties.

cond-mat.str-el↗
arXiv2008

LCG MCDB -- a Knowledgebase of Monte Carlo Simulated Events

In this paper we report on LCG Monte Carlo Data Base (MCDB) and software which has been developed to operate MCDB. The main purpose of the LCG MCDB project is to provide a storage and documentation system for sophisticated event samples simulated for the LHC collaborations by experts. In many cases, the modern Monte Carlo simulation of physical processes requires expert knowledge in Monte Carlo generators or significant amount of CPU time to produce the events. MCDB is a knowledgebase mainly dedicated to accumulate simulated events of this type. The main motivation behind LCG MCDB is to make the sophisticated MC event samples available for various physical groups. All the data from MCDB is accessible in several convenient ways. LCG MCDB is being developed within the CERN LCG Application Area Simulation project.

hep-ph↗
arXiv2006

A standard format for Les Houches Event Files

A standard file format is proposed to store process and event information, primarily output from parton-level event generators for further use by general-purpose ones. The information content is identical with what was already defined by the Les Houches Accord five years ago, but then in terms of Fortran commonblocks. This information is embedded in a minimal XML-style structure, for clarity and to simplify parsing.

hep-ph↗
arXiv2006

Les Houches Physics at TeV Colliders 2005, Standard Model and Higgs working group: Summary report

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

hep-ph↗