arXiv subjects

V. M. Katkov

Publications and source records attributed to V. M. Katkov.

At least 19 recordsLinked to original sources

arXiv2019

The effect of radiation corrections to the mass of an electron and positron on the polarization operator of a photon in a magnetic field

The polarization operator of a photon in a constant and uniform magnetic field is studied taking into account the radiation width and shift of the Landau levels in both weak and strong fields compared with the critical field $H_0=4,41\cdot10^{13}$ G . A general formula is obtained for the polarization operator of a photon in which radiation effects are taken into account. Now diverging previously threshold terms have a finite value. The conditions are formulated under which the energy levels completely overlap, and thereby the most appropriate application of the semiclassical operator method to the problem under study becomes.

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arXiv2015

Influence of an Electric Field on the Propagation of a Photon in a Magnetic field

In this work, a constant and uniform magnetic field is less than the Schwinger critical value. In turn, an additional constant and uniform electric field is taken much smaller than the magnetic field value. The propagation of a photon in this electromagnetic field is investigating. In particular, in the presence of a weak electric field, the root divergence is absent in the photon effective mass near the thresholds of pair creation. The effective mass of a real photon with a preset polarization is considered in the quantum energy region as well as in the quasiclassical one.

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arXiv2015

Polarization operator of a photon in a magnetic field

In the first order of the fine structer constant, the polarization operator of a photon is investigated in a constant and homogeneous magnetic field at arbitrary photon energies. For weak and strong fields H, compared with the Schwinger critical field, approximate expressions have been found. We consider the pure quantum region of photon energy near the threshold of pair creation, as well as the region of high energy levels where the quasiclassical approximation is valid. The general formula has been obtained for the effective mass of photon with given polarization. It is useful for an analysis of the problem under consideration on the whole and at a numerical work

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arXiv2014

Spectral-integral representation of the photon polarization operator in a constant uniform magnetic field

The polarization operator in a constant and homogeneous magnetic field of arbitrary strength is investigated on mass shell. The calculations are carried out at all photon energies higher the pair creation threshold as well as lower this threshold. The general formula for the effective mass of the photon with given polarization has been obtained being useful for an analysis of the problem under consideration as well as at a numerical work. Approximate expressions for strong or weak fields, compared with the critical field, have been found. Depending on the ratio of these fields we consider the pure quantum region of photon energy, where particles are created on lower Landau levels or created not at all. Also the energy region of large level numbers is considered where the quasiclassical approximation is valid.

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arXiv2014

On effective mass of a photon in a strong magnetic field

For the magnetic field in order of the Schwinger critical value or much larger it, the effective mass of a real photon with a preset polarization is investigated in the energy region including two lower creation thresholds of electron and positron on Landau levels. In the high-energy range, when the number of thresholds is large, the quasiclassical approach is used.

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arXiv2013

On structure of the polarization operator in a magnetic field

The polarization operator is investigated at arbitrary photon energy in a constant and homogeneous magnetic field for the strength H less than the Schwinger critical value. The effective mass of a real photon with a preset polarization is considered in the quantum energy region as well as in the quasiclassical one. Obtained in the quantum region expressions include the singular terms at the creation threshold of electron and positron on Landau levels.

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arXiv2011

Pair Photoproduction in Constant and Homogeneous Electromagnetic Fields

The process of pair creation by a photon in a constant and homogeneous electromagnetic field of an arbitrary configuration is investigating. At high energy the correction to the standard quasiclassical approximation (SQA) has been calculated. In the region of intermediate photon energies where SQA is inapplicable the new approximation, developed recently by authors, is used. The influence of weak electric field on the process in a magnetic field is considered. In particular, in the presence of electric field the root divergence in the probability of pair creation on the Landau energy levels is vanished. For smaller photon energies the low energy approximation is used. The found probability describes the absorption of soft photon by particles created by field. At low photon energy the electric field action dominates and the influence of magnetic field on the process is connected with the interaction of it and the magnetic moment of creating particles.

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arXiv2009

Pair creation by a photon in an electric field

The process of pair creation by a photon in a constant and homogeneous electric field is investigated basing on the polarization operator in the field. The total probability of the process is found in a relatively simple form. At high energy the quasiclassical approximation is valid. The corrections to the standard quasiclassical approximation (SQA) are calculated. In the region relatively low photon energies, where SQA is unapplicable, the new approximation is used. It is shown that in this energy interval the probability of pair creation by a photon in electric field exceeds essentially the corresponding probability in a magnetic field. This approach is valid at the photon energy much larger than "vacuum" energy in electric field: $ω\gg eE/m$. For smaller photon energies the low energy approximation is developed. At $ω\ll eE/m$ the found probability describes the absorption of soft photon by the particles created by an electric field.

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arXiv2009

Spectra of radiation and created particles at intermediate energy in oriented crystal taking into account energy loss

The spectral distribution of positron created by photon and the spectral distribution of photons radiated from electron in an oriented single crystal of intermediate thickness is calculated at intermediate energies. The energy loss of charged particles as well as photon absorption are taken into account. The used basic probabilities of processes include the action of field of axis as well as the multiple scattering of radiating electron or particles of the created pair (the Landau-Pomeranchuk-Migdal (LPM) effect)

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arXiv2008

Electroproduction of electron-positron pair in oriented crystal at high energy

The process of electroproduction of the electron-positron pair by high energy electron in an oriented single crystal is investigated. Two contributions are considered: the direct (one-step) process via the virtual intermediate photon and the cascade(two-step) process when the electron emits the real photon moving in the field of axis and afterwards the photon converts into the pair. The spectrum of created positron(electron) is found. It is shown that the probability of the process is strongly enhanced comparing with the corresponding amorphous medium.

hep-ph↗

arXiv2008

Electroproduction of electron-positron pair in a medium

The process of electron-positron pair creation by a high-energy electron in a medium is analyzed. The spectral distribution over energies of created particles is calculated for the direct and cascade mechanisms of the process. The Coulomb corrections are included. The new formulation of the equivalent photons method is developed which takes into account the influence of multiple scattering. It is shown the effects of multiple scattering can be quite effectively studied in the process under consideration.

hep-ph↗

arXiv2007

Opportunity to study the LPM effect in oriented crystal at GeV energy

The spectral distribution of electron-positron pair created by photon and the spectral distribution of photons radiated from high-energy electron in an oriented single crystal is calculated using the method which permits inseparable consideration both of the coherent and incoherent mechanisms of two relevant processes. The method includes the action of field of axis (or plane) as well as the multiple scattering of radiating electron or particles of the created pair (the Landau-Pomeranchuk-Migdal (LPM) effect). The influence of scattering on the coherent mechanism and the influence of field on the incoherent mechanism are analyzed. In tungsten, axis $<111>$ for the pair creation process at temperature T= 100 K the LPM effect attains 8 % at photon energy 5 GeV and for the radiation process at T= 293 K the LPM effect reaches 6 % at electron energy 10 GeV.

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arXiv2007

Spectrum and polarization of coherent and incoherent radiation and the LPM effect in oriented single crystal

The spectrum and the circular polarization of radiation from longitudinally polarized high-energy electrons in oriented single crystal are considered using the method which permits inseparable consideration of both the coherent and the incoherent mechanisms of photon emission. The spectral and polarization properties of radiation are obtained and analyzed. It is found that in some part of spectral distribution the influence of multiple scattering (the Landau-Pomeranchuk-Migdal (LPM) effect) attains the order of 7 percent. The same is true for the influence of multiple scattering on the polarization part of the radiation intensity. The degree of circular polarization of total intensity of radiation is found. It is shown that the influence of multiple scattering on the photon polarization is similar to the influence of the LPM effect on the total intensity of radiation: it appears only for relatively low energies of radiating electron and has the order of 1 percent, while at higher energies the crystal field action excludes the LPM effect.

hep-ph↗

arXiv2007

Pair creation by a photon in a strong magnetic field

The process of pair creation by a photon in a strong magnetic field is investigated basing on the polarization operator in the field. The total probability of the process is found in a relatively simple form. The probability exhibits a "saw-tooth" pattern because of divergences arising when the electron and positron are created at threshold of the Landau energy levels. The pattern will be washed out at averaging over any smooth photon energy distribution. The new results are obtained in the scope of the quasiclassical approach: 1) in the case when the magnetic field $B \ll B_0, (B_0$ is the critical field) the new formulation extends the photon energy interval to the case when the created particles are not ultrarelativistic; 2) the correction to the standard quasiclassical approximation is found showing the range of applicability of the approach at high photon energy as well. The very important conclusion is that for both cases $B \ll B_0$ and $B \geq B_0$ the results of the quasiclassical calculation are very close to averaged probabilities of exact theory in a very wide range of photon energies. The quasiclassical approximation is valid also for the energy distribution if the electron and positron are created on enough high levels.

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arXiv2006

Coherent and incoherent processes and the LPM effect in oriented single crystals at high-energy

The process of radiation from high-energy electron and electron-positron pair production by a photon in oriented single crystal is considered using the method which permits inseparable consideration of both coherent and incoherent mechanisms of photon emission from an electron and of pair creation by a photon and includes the action of field of axis (or plane) as well as the multiple scattering of radiating electron or particles of the created pair (the Landau-Pomeranchuk-Migdal (LPM) effect). The total intensity of radiation and total probability pair creation are calculated. The theory, where the energy loss of projectile has to be taken into account, and found probabilities of pair creation agree quite satisfactory with available CERN data. From obtained results it follows that multiple scattering appears only for relatively low energy of radiating electron or a photon, while at higher energies the field action excludes the LPM effect.

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arXiv2005

Coherent and incoherent radiation from high-energy electron and the LPM effect in oriented single crystal

The process of radiation from high-energy electron in oriented single crystal is considered using the method which permits inseparable consideration of both coherent and incoherent mechanisms of photon emission. The total intensity of radiation is calculated. The theory, where the energy loss of projectile has to be taken into account, agrees quite satisfactory with available CERN data. It is shown that the influence of multiple scattering on radiation process is suppressed due to action of crystal field.

hep-ph↗

arXiv2005

Polarization effects for pair creation by photon in oriented crystals at high energy

Pair creation by a photon in an oriented crystal is considered in a frame of the quasiclassical operator method, which includes processes with polarized particles. Under some quite generic assumptions the general expression is derived for the probability of pair creation of longitudinally polarized electron (positron) by circularly polarized photon in oriented crystal. In particular cases $\vartheta_0 \ll V_0/m$ and $\vartheta_0 \gg V_0/m$ ($\vartheta_0$ is the angle of incidence, angle between the momentum of initial photon and axis (plane) of crystal, $V_0$ is the scale of a potential of axis or a plane relative to which the angle $\vartheta_0$ is defined) one has constant field approximation and the coherent pair production theory correspondingly. Side by side with coherent process the probability of incoherent pair creation is calculated, which differs essentially from amorphous one. At high energy the pair creation in oriented crystals is strongly enhanced comparing with amorphous medium. In appendixes the integral polarization of positron is found in external field and for coherent and incoherent mechanisms.

hep-ph↗

arXiv2005

Coherent and incoherent pair creation by a photon in oriented single crystal

The new approach is developed for study of electron-positron pair production by a photon in oriented single crystal. It permits indivisible consideration of both coherent and incoherent mechanisms of pair creation and includes the action of field of axis (or plane) as well as the multiple scattering of particles of the created pair (the Landau-Pomeranchuk-Migdal (LPM) effect). From obtained integral probability of pair creation, it follows that multiple scattering appears only for relatively low energy of photon, while at higher photon energy the field action excludes the LPM effect. The found results agree quite satisfactory with recent CERN experiment.

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