Searcharxiv⌕ Search

arXiv subjects

A. A. Gvozdev

Publications and source records attributed to A. A. Gvozdev.

At least 19 recordsLinked to original sources
arXiv2011

Lower Bound on the Magnetic Field Strength of a Magnetar from Analysis of SGR Giant Flares

Based on the magnetar model, we have studied in detail the processes of neutrino cooling of an electron--positron plasma generating an SGR giant flare and the influence of the magnetar magnetic field on these processes. Electron--positron pair annihilation and synchrotron neutrino emission are shown to make a dominant contribution to the neutrino emissivity of such a plasma. We have calculated the neutrino energy losses from a plasma-filled region at the long tail stage of the SGR 0526--66, SGR 1806--20, and SGR 1900+14 giant flares. This plasma can emit the energy observed in an SGR giant flare only in the presence of a strong magnetic field suppressing its neutrino energy losses. We have obtained a lower bound on the magnetic field strength and showed this value to be higher than the upper limit following from an estimate of the magnetic dipole losses for the magnetars being analyzed in a wide range of magnetar model parameters. Thus, it is problematic to explain the observed energy release at the long tail stage of an SGR giant flare in terms of the magnetar model.

astro-ph.HE↗
arXiv2006

Neutrino heating of a shock wave within magnetorotational model

Based on the magnetorotational model of a supernova explosion with core collapse, we investigate the significant processes of neutrino heating of the supernova shock. These processes should be taken into account in self-consistent modeling, since the neutrino heating mechanism is capable of increasing the explosion efficiency. We show that, even in the presence of a strong magnetic field in the shock formation region, the heating rate is determined with good accuracy by the absorption and emission of neutrinos in direct URCA processes. Moreover, the influence on them of a magnetic field is reduced to insignificant corrections.

astro-ph↗
arXiv2004

Neutrino Interaction with Nucleons in the Envelope of a Collapsing Star with a Strong Magnetic Field

The interaction of neutrinos with nucleons in the envelope of a remnant of collapse with a strong magnetic field during the passage of the main neutrino flux is investigated. General expressions are derived for the reaction rates and for the energy-momentum transferred to the medium through the neutrino scattering by nucleons and in the direct URCA processes. Parameters of the medium in a strong magnetic field are calculated under the condition of quasi-equilibrium with neutrinos. Numerical estimates are given for the neutrino mean free paths and for the density of the force acting on the envelope along the magnetic field. It is shown that in a strong toroidal magnetic field, the envelope region partially transparent to neutrinos can acquire a large angular acceleration on the passage time scales of the main neutrino flux.

astro-ph↗
arXiv2002

Efficiency of Electron-Positron Pair Productionby Neutrino Flux from Accretion Disk of a Kerr Black Hole

Dominant processes of neutrino production and neutrino-induced \ep-pair production are examined in the model of a disk hyper-accreting onto a Kerr black hole. The efficiency of plasma production by a neutrino flux from the disk, obtained for the both cases of presence and absence of a magnetic field, is found to be no more than several tenths of percent and, therefore, not enough for the origin of cosmological gamma-ray bursts.

astro-ph↗
arXiv1999

Kick asymmetry along a strong magnetic field in the process of neutrino scattering on nucleons

The neutrino-nucleon scattering in a collapsing star envelope with a strong magnetic field is investigated. The transferred by neutrinos momentum asymmetry along the field direction is obtained. It is shown that the neutrino-nucleon scattering gives a contribution to the asymmetry comparable with direct URCA processes. Hence, the neutrino-nucleon scattering should be taken into account in estimations of a possible influence of neutrino reemission processes on a collapsing star envelope dynamics.

astro-ph↗
arXiv1999

Influence of direct URCA processes in a strong magnetic field on dynamics of collapsing star envelope

Direct URCA processes in a collapsing star envelope with a strong magnetic field are investigated. It is shown that in the toroidal magnetic field these processes can develope a torque which quickly unwinds an envelope. A general expression for a force density along the field direction is obtained. An influence of the neutrino unwinding effect on a dynamics of the collapsar envelope is discussed and numerically estimated.

astro-ph↗
arXiv1999

On the Possible Enhancement of the Magnetic Field by Neutrino Reemission Processes in the Mantle of a Supernova

URCA neutrino reemission processes under the conditions in the mantle of a supernova with a strong toroidal magnetic field are investigated. It is shown that parity violation in these processes can be manifested macroscopically as a torque that rapidly spins up the region of the mantle occupied by such a field. Neutrino spin-up of the mantle can strongly affect the mechanism of further generation of the toroidal field, specifically, it can enhance the field in a small neighborhood of the rigid-body-rotating core of the supernova remnant.

astro-ph↗
arXiv1997

Neutrino transitions nu -> nu gamma, nu -> nu e+ e- in a strong magnetic field as a possible origin of cosmological gamma-burst

The high energy neutrino transitions with the photon and electron-positron pair creation in a strong magnetic field in the framework of the Standard Model are investigated. The process probabilities and the mean values of the neutrino energy and momentum loss are presented. The asymmetry of outgoing neutrinos, as a possible source of sufficient recoil ``kick'' velocity of a remnant and the emission of e+ e- pairs and gamma-quanta in a ``polar cap'' region of a remnant, as a possible origin of cosmological gamma-burst are discussed.

hep-ph↗
arXiv1997

Creation of photons and electron - positron pairs by a neutrino in a strong magnetic field

The processes of the photon and electron-positron pair production by a neutrino propagating in a strong magnetic field are investigated in the framework of the Standard Model. The process probabilities and the mean values of the neutrino energy and momentum loss are calculated. Possible astrophysical manifestations of the processes considered are briefly analysed.

hep-ph↗
arXiv1997

Radiative Transition of Massless Neutrino in Strong Magnetic Field

Radiative transition of massless neutrino $ν_l \to ν_l + γ$ ($l = e, μ, τ$) in a strong magnetic field is investigated in the framework of the Standard Model. The process probability and the mean values of the neutrino energy and momentum loss are presented. Possible astrophysical manifestation of the process considered is analysed.

hep-ph↗
arXiv1997

Resonance neutrino bremsstrahlung $ν\to νγ$ in a strong magnetic field

High energy neutrino bremsstrahlung $ν\to ν+ γ$ in a strong magnetic field ($B \gg B_s$) is studied in the framework of the Standard Model (SM). A resonance probability and a four-vector of the neutrino energy and momentum loss are presented. A manifestation of the neutrino bremsstrahlung in astrophysical cataclysm of type of a supernova explosion or a merger of neutron stars, such as an possible origin of cosmological $γ$-burst is discussed.

hep-ph↗
arXiv1996

The radiative decay of the massive neutrino in the external electromagnetic fields

The radiative decay of the massive neutrino $ν_i \rightarrow ν_j γ$ is investigated in the framework of the Standard Model in external electromagnetic fields of various configurations: constant crossed field, constant uniform magnetic field, plane monochromatic wave's field. The effect of significant enhancement of the neutrino decay probability by the external field (electromagnetic catalysis) is discussed. An especially strong enhancement occurs in the case of the ultrarelativistic neutrino decay, since in this case the decay probability does not contain suppression caused by the smallness of the decaying neutrino mass. The ultrarelativistic neutrino decay catalysis is significant even in a relatively weak external field ($F/F_e << 1$, where $F_e$ is the critical Schwinger value). The expression for the photon splitting probability into the neutrino pair $γ\rightarrow ν_i \barν_j$ in the wave field is given. The estimations of a number of gamma-quanta produced in a volume filled with an electromagnetic field and the neutrino lifetime in a strong magnetic field are presented.

hep-ph↗
arXiv1995

Unitary Limit on $K^0_L \to μ^+ μ^-$ and the Top Quark Mass

A brief overview of the recent measurements of the branching ratio of the rare $K_L^0 \to μ^+ μ^-$ decay in the context of their agreement with the Standard Model (SM) is given. It is shown that KEK result well correlates with the SM and B-physics, whereas the BNL results are in conflict with the SM with the heavy top quark.

hep-ph↗
arXiv1995

Electromagnetic Catalysis of a Neutrino Radiative decay or One More Source of Information on the Lepton Mixing Angles?

The radiative decay of ultrarelativistic massive neutrino $ν_i \rightarrow ν_j γ$ is investigated in electromagnetic fields in the framework of the Standard Model with lepton mixing. Estimates of the decay probability and ``decay cross-section'' for accelerator neutrinos of high energies in the electric field of nucleus permit one to discuss the general possibility of carrying out the neutrino experiment. Such an experiment could give unique information on mixing angles in the lepton sector of the Standard Model which would be almost independent of the specific neutrino masses.

hep-ph↗
arXiv1995

THREE TYPES OF FERMION MIXING AND POSSIBLE MANIFESTATIONS OF A PATI--SALAM LEPTOQUARK IN THE LOW--ENERGY PROCESSES

I report the recent studies\cite{1,2} on the low--energy manifestations of a minimal extension of the Standard Model based on the quark-lepton symmetry $SU(4)_V \otimes SU(2)_L \otimes G_R$ of the Pati-Salam type. Given this symmetry the third type of mixing in the interactions ot the $SU(4)_V$ leptoquarks with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow, in principle, to decrease noticeably the lower bound on the vector leptoquark mass originated from the low-energy rare processes. The decays $μ\rightarrow e γ$, $μ\rightarrow e γγ$, and $μ\rightarrow e e \bar e$ via the vector leptoquark are analysed and the specific hierarchy of the decay probabilities $Γ(μ\rightarrow e e \bar e) \gg Γ(μ\rightarrow e γγ) \gg Γ(μ\rightarrow e γ)$ is shown to exist. The upper limits on the branching ratios at a level of $10^{-18}$ for the $μ\rightarrow e γγ$ decay and at a level of $10^{-15}$ for the $μ\rightarrow e e \bar e$ decay are established.

hep-ph↗
arXiv1994

Muon decays with lepton--number violation via vector leptoquark

The decays $μ\rightarrow e γ$, $μ\rightarrow e γγ$, and $μ\rightarrow e e \bar e$ are analysed in the framework of the Pati-Salam type quark-lepton symmetry $SU(4)_V \otimes SU(2)_L \otimes G_R$ where the effects of mixing in the quark-lepton currents are taken into account. It is shown that the $μ\rightarrow e γγ$ and $μ\rightarrow e e \bar e$ decays via the vector leptoquark have not a GIM--type suppression, while the $μ\rightarrow e γ$ decay has. So, the specific hierarchy of the decay probabilities could take place $Γ(μ\rightarrow e e \bar e) \gg Γ(μ\rightarrow e γγ) \gg Γ(μ\rightarrow e γ)$. The existing bounds on the vector leptoquark mass and on the mixing matrix elements, based on the data for the $μe$ conversion in nuclei and for the ratio of the $K_{e 2}$ and $K_{μ2}$ decays allow to set the upper limits on the branching ratios at a level of $10^{-18}$ for the $μ\rightarrow e γγ$ decay and at a level of $10^{-15}$ for the $μ\rightarrow e e \bar e$ decay.

hep-ph↗
arXiv1994

One More Source of Information on the Lepton Mixing Angles

In the framework of the Standard Model with lepton mixing the radiative decay $ν_i \rightarrow ν_j γ$ of a neutrino of high ($E_ν\sim 100 \, GeV$) and super-high ($E_ν\ge 1 \, TeV$) energy is investigated in the Coulomb field of a nucleus. Estimates of the decay probability and ``decay cross-section'' for neutrinos of these energies in the electric field of nucleus permit one to discuss the general possibility of carrying out the neutrino experiment, subject to the condition of availability in the future of a beam of neutrinos of that high energies. Such an experiment could give unique information on mixing angles in the lepton sector of the Standard Model which would be independent of the specific neutrino masses if only the threshold factor ($1 - m_j^4 / m_i^4$) was not close to zero.

hep-ph↗