arXiv subjects

S. I. Kruglov

Publications and source records attributed to S. I. Kruglov.

At least 55 records · Page 3Linked to original sources

arXiv2019

Magnetized black holes and nonlinear electrodynamics

A new model of nonlinear electrodynamics with two parameters is proposed. We study the phenomenon of vacuum birefringence, the causality and unitarity in this model. There is no singularity of the electric field in the center of point-like charges and the total electrostatic energy is finite. We obtain corrections to the Coulomb law at $r\rightarrow\infty$. The weak, dominant and strong energy conditions are investigated. Magnetized charged black hole is considered and we evaluate the mass, metric function and their asymptotic at $r\rightarrow\infty$ and $r\rightarrow 0$. The magnetic mass of the black hole is calculated. The thermodynamic properties and thermal stability of regular black holes are discussed. We calculate the Hawking temperature of black holes and show that there are first-order and second-order phase transitions. The parameters of the model when the black hole is stable are found.

gr-qc↗

arXiv2019

Born - Infeld-type modified gravity

We propose and investigate the modified Born$-$Infeld-type gravity model with the function $F(R) = [1-(1-βR/σ)^σ]/β$. At different values of the dimensionless parameter $σ$ the action is converted into some models including general relativity ($σ=1$), the Starobinsky model ($σ=2$), the exponential model of gravity ($σ=\infty$), and a model proposed in [9], [10] ($σ=0.5$). A bound on the parameters, $β(1-σ)/σ\leq 2\times 10^{-6}$ cm$^2$, are due to local tests. The constant curvature solutions are obtained, and we found the potential, and the mass of the scalaron in the Einstein frame. The model describes the inflation of the universe. The de Sitter spacetime is unstable and a Minkovsky spacetime is stable. We investigate the cosmological parameters and some critical points of autonomous equations.

physics.gen-ph↗

arXiv2018

Holographic superconductor with nonlinear Born - Infeld-type electrodynamics

Holographic s-wave superconductors in the framework of nonlinear Born - Infeld-type electrodynamics is investigated in the background of Schwarzschild anti-de Sitter black holes. As particular cases, at some model parameters, we obtain results for Born - Infeld and exponential electrodynamics. We explore the analytical Sturm-Liouville eigenvalue problem in the probe limit where the scalar and electromagnetic fields do not effect on the background metric. The critical temperatures of phase transitions and the order parameter are calculated which depend on the model parameters. We show that the critical exponent near the critical temperature is 1/2. Making use of the matching method we derive analytical expressions for the condensation values and the critical temperature. The conductivity by the analytical method is calculated.

hep-th↗

arXiv2018

Holographic superconductor with nonlinear arcsin-electrodynamics

We investigate holographic s-wave superconductors with nonlinear arcsin-electrodynamics in the background of Schwarzschild anti-de Sitter black holes. The analytical Sturm-Liouville eigenvalue problem is explored and we assume that the scalar and electromagnetic fields do not influence on the background metric (the probe limit). The critical temperatures of phase transitions depending on the parameter of the model is obtained. We show that in our case the condensation formation becomes easier compared to Born-Infeld nonlinear electrodynamics. The critical exponent near the critical temperature is calculated which is 1/2. With the help of the matching method we derive analytic expressions for the condensation value and the critical temperature. The real and imaginary parts of the conductivity in our model, making use of an analytical method, are computed.

hep-th↗

arXiv2018

On a model of magnetically charged black hole with nonlinear electrodynamics

The Bronnikov model of nonlinear electrodynamics is investigated in general relativity. The magnetic black hole is considered and we obtain a solution giving corrections to the Reissner-Nordström solution. In this model spacetime at $r\rightarrow\infty$ becomes Minkowski's spacetime. We calculate the magnetic mass of the black hole and the metric function. At some parameters of the model there can be one, two or no horizons. The Hawking temperature and the heat capacity of black holes are calculated. We show that a second-order phase transition takes place and black holes are thermodynamically stable at some range of parameters.

gr-qc↗

arXiv2018

Magnetically charged black hole in framework of nonlinear electrodynamics model

A model of nonlinear electrodynamics is proposed and investigated in general relativity. We consider the magnetic black hole and find a regular solution which gives corrections into the Reissner-Nordström solution. At $r\rightarrow\infty$ the asymptotic spacetime becomes flat. The magnetic mass of the black hole is calculated and the metric function is obtained. At some values of the model parameter there can be one, two or no horizons. Thermodynamics of black holes is studied and we calculate the Hawking temperature and heat capacity of black holes. It is demonstrated that there is a phase transition of second order. At some parameters of the model black holes are thermodynamically stable.

physics.gen-ph↗

arXiv2017

Notes on Born-Infeld-type electrodynamics

We propose a new model of nonlinear electrodynamics with three parameters. Born-Infeld electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence is studied. We show that there is not singularity of the electric field at the origin of point-like charged particles. The corrections to Coulomb's law at $r\rightarrow\infty$ are obtained. We calculate the total electrostatic energy of charges for different parameters of the model which is finite.

physics.gen-ph↗

arXiv2017

Nonlinear electrodynamics and magnetic black holes

A model of nonlinear electrodynamics with two parameters, coupled with general relativity, is investigated. We study the magnetized black hole and obtain solutions. The asymptotic of the metric and mass functions at $r\rightarrow\infty$ and $r\rightarrow 0$, and corrections to the Reissner-Nordström solution are found. We investigate thermodynamics of black holes and calculate the Hawking temperature and heat capacity of black holes. It is shown that there are phase transitions and at some parameters of the model black holes are stable.

gr-qc↗

arXiv2017

Energy Spectrum of anyon in the Coulomb field

One of the interesting fundamental phenomenon which was observed in the last decades is the discovery of anyons, relativistic spinning particles in $2+1$ dimensions. In contrast to three-dimensional space, indistinguishable quantum particles in two-dimensional space can, in general, have anomalous statistics [1-4]. These quasiparticles carry not only a charge $q$ also the magnetic flux $Φ_0$.

quant-ph↗

arXiv2017

Remarks on Heisenberg-Euler-type electrodynamics

We consider Heisenberg-Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg-Euler electrodynamics is a particular case of this model. Corrections to Coulomb's law at $r\rightarrow\infty$ are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at $r\rightarrow\infty$. Corrections to the Reissner-Nordström solution are obtained.

physics.gen-ph↗

arXiv2017

Inflation of universe due to nonlinear electrodynamics

A model of nonlinear electrodynamics with a dimensional parameter $β$ is considered. Electromagnetic fields are the source of the gravitation field and inflation of the universe. We imply that the universe is filled by stochastic magnetic fields. It is demonstrated that after the universe inflation the universe decelerates approaching the Minkowski spacetime. We evaluate the spectral index, the tensor-to-scalar ratio, and the running of the spectral index which approximately agree with the PLANK and WMAP data.

gr-qc↗

arXiv2017

Black hole as a magnetic monopole within exponential nonlinear electrodynamics

We perform the gauge covariant quantization of the exponential model of nonlinear electrodynamics. Magnetically charged black holes, in the framework of our model are considered, and the regular black hole solution is obtained in general relativity. The asymptotic black hole solution at $r\rightarrow \infty$ is found. We calculate the magnetic mass of the black hole and the metric function which are expressed via the parameter $β$ of the model and the magnetic charge. The thermodynamic properties and thermal stability of regular black holes are analysed. We calculate the Hawking temperature of black holes and their heat capacity at the constant magnetic charge. We find a point where the temperature changes the sign that corresponds to the first-order phase transition. It is shown that at critical point, where the heat capacity diverges, there is a phase transition of the second-order. We obtain the parameters of the model when the black hole is stable.

gr-qc↗

arXiv2017

Modified Gibbs's representation of rotation matrix

A modified Gibbs's rotation matrix is derived and the connection with the Euler angles, quaternions, and Cayley$-$Klein parameters is established. As particular cases, the Rodrigues and Gibbs parameterizations of the rotation are obtained. The composition law of two rotations from the quaternion representation is presented showing a convenient expression for calculating the successive rotations.

physics.gen-ph↗

arXiv2017

Black hole solution in the framework of $\arctan$-electrodynamics

An $arctan$-electrodynamics coupled with the gravitational field is investigated. We obtain the regular black hole solution that at $r\rightarrow \infty$ gives corrections to the Reissner-Nordström solution. The corrections to Coulomb's law at $r\rightarrow\infty$ are found. We evaluate the mass of the black hole that is a function of the dimensional parameter $β$ introduced in the model. The magnetically charged black hole was investigated and we have obtained the magnetic mass of the black hole and the metric function at $r\rightarrow \infty$. The regular black hole solution is obtained at $r\rightarrow 0$ with the de Sitter core. We show that there is no singularity of the Ricci scalar for electrically and magnetically charged black holes. Restrictions on the electric and magnetic fields are found that follow from the requirement of the absence of superluminal sound speed and the requirement of a classical stability.

physics.gen-ph↗

arXiv2016

Corrections to Reissner-Nordström black hole solution due to exponential nonlinear electrodynamics

An exponential model of nonlinear electrodynamics coupled with the gravitational field is analyzed. It was shown that weak, dominant, and strong energy conditions are satisfied. We obtain corrections to Coulomb's law at $r\rightarrow\infty$. It was demonstrated that electric-magnetic duality between ${\cal F}$ and ${\cal P}$ frames is violated. The asymptotic black hole solution at $r\rightarrow \infty$ is found that contains corrections to the Reissner-Nordström solution. The electromagnetic mass of the black hole is calculated, expressed through the parameter $β$ of the model.

physics.gen-ph↗

arXiv2016

Asymptotic Reissner-Nordström solution within nonlinear electrodynamics

A model of nonlinear electrodynamics coupled with the gravitational field is studied. We obtain the asymptotic black hole solutions at $r\rightarrow 0$ and $r\rightarrow \infty$. The asymptotic at $r\rightarrow 0$ is shown, and we find corrections to the Reissner-Nordström solution and Coulomb's law at $r\rightarrow\infty$. The mass of the black hole is evaluated having the electromagnetic origin. We investigate the thermodynamics of charged black holes and their thermal stability. The critical point corresponding to the second-order phase transition (where heat capacity diverges) is found. If the mass of the black hole is greater than the critical mass, the black hole becomes unstable.

gr-qc↗

arXiv2016

Nonlinear $\arcsin$-electrodynamics and asymptotic Reissner-Nordström black holes

A model of nonlinear electrodynamics with the Lagrangian density ${\cal L} = -(1/β)\arcsin(βF_{μν}F^{μν}/4)$ is proposed. The scale invariance and the dual invariance of electromagnetic fields are broken in the model. In the limit $β\rightarrow 0$ one comes to Maxwell's electrodynamics and the scale and dual invariances are recovered. We investigate the effect of coupling electromagnetic fields with the gravitational field. The asymptotic black hole solution is found which is similar to the Reissner-Nordström solution. We obtain corrections to Coulomb's law and to the Reissner-Nordström solution in the model proposed. The existence of the regular asymptotic at $r\rightarrow 0$ was demonstrated. The mass of the black hole is calculated possessing the electromagnetic origin. It was shown that there are not superluminal fluctuations and principles of causality and unitarity take place.

gr-qc↗

arXiv2016

Modified nonlinear model of arcsin-electrodynamics

A new modified model of nonlinear arcsin-electrodynamics with two parameters is proposed and analyzed. We obtain the corrections to the Coulomb law. The effect of vacuum birefringence takes place when the external constant magnetic field is present. We calculate indices of refraction for two perpendicular polarizations of electromagnetic waves and estimate bounds on the parameter $γ$ from the BMV and PVLAS experiments. It is shown that the electric field of a point-like charge is finite at the origin. We calculate the finite static electric energy of point-like particles and demonstrate that the electron mass can have the pure electromagnetic nature. The symmetrical Belinfante energy-momentum tensor and dilatation current are found. We show that the dilatation symmetry and dual symmetry are broken in the model suggested. We have investigated the gauge covariant quantization of the nonlinear electrodynamics fields as well as the gauge fixing approach based on Dirac's brackets.

hep-ph↗