arXiv subjects
Publications and source records attributed to Maxim Dvornikov.
Using the quantum field theory methods, we calculate the helicity flip of an electron scattering off protons in dense matter of a neutron star. The influence of the electroweak interaction between electrons and background nucleons on the helicity flip is examined. We also derive the kinetic equation for the chiral imbalance. The derived kinetic equation is compared with the results obtained by other authors.
The description of physical processes in accelerated frames opens a window to numerous new phenomena. One can encounter these effects both in the subatomic world and on a macroscale. In the present work we review our recent results on the study of the electroweak interaction of particles with an accelerated background matter. In our analysis we choose the noninertial comoving frame, where matter is at rest. Our study is based on the solution of the Dirac equation, which exactly takes into account both the interaction with matter and the nonintertial effects. First, we study the interaction of ultrarelativistic neutrinos, electrons and quarks with the rotating matter. We consider the influence of the matter rotation on the resonance in neutrino oscillations and the generation of anomalous electric current of charged particles along the rotation axis. Then, we study the creation of neutrino-antineutrino pairs in a linearly accelerated matter. The applications of the obtained results for elementary particle physics and astrophysics are discussed.
We study the magnetic field generation in a neutron star within the model based on the magnetic field instability in the nuclear matter owing to the electron-nucleon parity violating interaction. We suggest that the growing magnetic field takes the energy from thermal background fermions in the neutron star matter. The system of kinetic equations for the spectra of the magnetic helicity density and magnetic energy density as well as the chiral imbalance are solved numerically accounting for this energy source. We obtain that, for the initial conditions corresponding to a typical neutron star, the large scale magnetic field $\sim 10^{15}\thinspace\text{G}$ is generated during $(10^4-10^5)\thinspace\text{yr}$. We suggest that the proposed model describes strong magnetic fields observed in magnetars.
We study the evolution of neutrinos in a background matter moving with a linear acceleration. The Dirac equation for a massive neutrino electroweakly interacting with background fermions is obtained in a comoving frame where matter is at rest. We solve this Dirac equation for ultrarelativistic neutrinos. The neutrino quantum states in matter moving with a linear acceleration are obtained. We demonstrate that the neutrino electroweak interaction with an accelerated matter leads to the vacuum instability which results in the neutrino-antineutrino pairs creation. We rederive the temperature of the Unruh radiation and find the correction to the Unruh effect due to the specific neutrino interaction with background fermions. As a possible application of the obtained results we discuss the neutrino pairs creation in a core collapsing supernova. The astrophysical upper limit on the neutrino masses is obtained.
We study Dirac neutrinos propagating in rotating background matter. First we derive the Dirac equation for a single massive neutrino in the noninertial frame, where matter is at rest. This equation is written in the effective curved space-time corresponding to the corotating frame. We find the exact solution of the Dirac equation. The neutrino energy levels for ultrarelativistic particles are obtained. Then we discuss several neutrino mass eigenstates, with a nonzero mixing between them, interacting with rotating background matter. We derive the effective Schrödinger equation governing neutrino flavor oscillations in rotating matter. The new resonance condition for neutrino oscillations is obtained. We also examine the correction to the resonance condition caused by the matter rotation.
We study the instability of magnetic fields in a neutron star core driven by the parity violating part of the electron-nucleon interaction in the Standard Model. Assuming a seed field of the order $10^{12}\thinspace\text{G}$, that is a common value for pulsars, one obtains its amplification due to such a novel mechanism by about five orders of magnitude, up to $10^{17}\thinspace\text{G}$, at time scales $\sim (10^3 - 10^5)\thinspace\text{yr}$. This effect is suggested to be a possible explanation of the origin of the strongest magnetic fields observed in magnetars. The growth of a seed magnetic field energy density is stipulated by the corresponding growth of the magnetic helicity density due to the presence of the anomalous electric current in the Maxwell equation. Such an anomaly is the sum of the two competitive effects: (i) the chiral magnetic effect driven by the difference of chemical potentials for the right and left handed massless electrons and (ii) constant chiral electroweak electron-nucleon interaction term, which has the polarization origin and depends on the constant neutron density in a neutron star core. The remarkable issue for the decisive role of the magnetic helicity evolution in the suggested mechanism is the arbitrariness of an initial magnetic helicity including the case of non-helical fields from the beginning. The tendency of the magnetic helicity density to the maximal helicity case at large evolution times provides the growth of a seed magnetic field to the strongest magnetic fields in astrophysics.
We study electroweakly interacting particles in rotating matter. The existence of the electric current along the axis of the matter rotation is predicted in this system. This new galvano-rotational effect is caused by the parity violating interaction between massless charged particles in the rotating matter. We start with the exact solution of the Dirac equation for a fermion involved in the electroweak interaction in the rotating frame. This equation includes the noninertial effects. Then, using the obtained solution, we derive the induced electric current which turns out to flow along the rotation axis. We study the possibility of the appearance of the galvano-rotational effect in dense matter of compact astrophysical objects. The particular example of neutron and hypothetical quark stars is discussed. It is shown that, using this effect, one can expect the generation of toroidal magnetic fields comparable with poloidal ones in old millisecond pulsars. We also briefly discuss the generation of the magnetic helicity in these stars. Finally we analyze the possibility to apply the galvano-rotational effect for the description of the asymmetric neutrino emission from a neutron star to explain pulsars kicks.
We construct the model of a quantum spherically symmetric plasma structure based on radial oscillations of ions. We suppose that ions are involved in ion-acoustic plasma oscillations. We find the exact solution of the Schrödinger equation for an ion moving in the self-consistent oscillatory potential of an ion-acoustic wave. The system of ions is secondly quantized and its ground state is constructed. Then we consider the interaction between ions by the exchange of an acoustic wave. It is shown that this interaction can be attractive. We describe the formation of pairs of ions inside a plasma structure and demonstrate that such a plasmoid can exist in a dense astrophysical medium corresponding to the outer core of a neutron star.
We show that the Standard Model electroweak interaction of ultrarelativistic electrons with nucleons ($eN$ interaction) in a neutron star (NS) permeated by a seed large-scale helical magnetic field provides its growth up to $\gtrsim 10^{15}\thinspace\text{G}$ during a time comparable with the ages of young magnetars $\sim 10^4\thinspace\text{yr}$. The magnetic field instability originates from the parity violation in the $eN$ interaction entering the generalized Dirac equation for right and left massless electrons in an external uniform magnetic field. We calculate the averaged electric current given by the solution of the modified Dirac equation containing an extra current for right and left electrons (positrons), which turns out to be directed along the magnetic field. Such current includes both a changing chiral imbalance of electrons and the $eN$ potential given by a constant neutron density in NS. Then we derive the system of the kinetic equations for the chiral imbalance and the magnetic helicity which accounts for the $eN$ interaction. By solving this system, we show that a sizable chiral imbalance arising in a neutron protostar due to the Urca-process $e^-_\mathrm{L} + p\to N + ν_\mathrm{eL}$ diminishes very rapidly because of a huge chirality flip rate. Thus the $eN$ term prevails the chiral effect providing a huge growth of the magnetic helicity and the helical magnetic field.
We study the system of massive and mixed neutrinos interacting with background matter moving with an acceleration. We start with the derivation of the Dirac equation for a single neutrino in the noninertial frame where matter is at rest. A particular case of matter rotating with a constant angular velocity is considered. The Dirac equation is solved and the neutrino energy levels are found for ultrarelativistic particles propagating in rotating matter. Then we generalize our results to include several neutrino generations and consider mixing between them. Using the relativistic quantum mechanics approach we derive the effective Schrödinger equation for the description of neutrino flavor oscillations in rotating matter. We obtain the resonance condition for neutrino oscillations and examine how it can be affected by the matter rotation. We also compare our results with the findings of other authors who studied analogous problem previously.
We study the generation of strong magnetic fields in magnetars and in the early universe. For this purpose we calculate the antisymmetric contribution to the photon polarization tensor in a medium consisting of an electron-positron plasma and a gas of neutrinos and antineutrinos, interacting within the Standard Model. Such a contribution exactly takes into account the temperature and the chemical potential of plasma as well as the photon dispersion law in this background matter. It is shown that a nonvanishing Chern-Simons parameter, which appears if there is a nonzero asymmetry between neutrinos and antineutrinos, leads to the instability of a magnetic field resulting to its growth. We apply our result to the description of the magnetic field amplification in the first second of a supernova explosion. It is suggested that this mechanism can explain strong magnetic fields of magnetars. Then we use our approach to study the cosmological magnetic field evolution. We find a lower bound on the neutrino asymmetries consistent with the well-known Big Bang nucleosynthesis bound in a hot universe plasma. Finally we examine the issue of whether a magnetic field can be amplified in a background matter consisting of self-interacting electrons and positrons.
We examine the issue whether a magnetic field can be amplified in a background matter consisting of electrons and positrons self-interacting within the Fermi model. For this purpose we compute the antisymmetric contribution to the photon polarization tensor in this matter having nonzero temperature and chemical potential. It is shown that this contribution is vanishing in the static limit. Then we study a particular case of a degenerate relativistic electron gas present in a magnetar. We demonstrate that a seed magnetic field is attenuated in this case. Thus, contrary to the recent claim, we show that there is no magnetic field instability in such a system, which can lead to the magnetic field growth. Therefore recently proposed mechanism cannot be used for the explanation of strong magnetic fields of magnetars.
I study stable spatial Langmuir solitons in plasma based on nonlinear radial oscillations of charged particles. I discuss two situations when a Langmuir soliton can be stable. In the former case the stability of solitons against the collapse is due to electron-electron interactions which result in the nonlocal terms in the nonlinear Schrödinger equation. In the latter situation I derive the new cubic-quintic nonlinear Schrödinger equation with accounts for the interaction of induced dipole moments of diatomic ions with a rapidly oscillating electric field and show that the collapse of Langmuir waves can be also arrested. In both cases I find the numerical solutions of the nonlinear Schrödinger equation and analyze their stability using the Vakhitov-Kolokolov criterion. I discuss the application of my results for the description of long-lived atmospheric plasma structures. I show that, using my model, one can explain the existence of atmospheric plasmoids in the upper ionosphere. It is also demonstrated that Langmuir solitons described by the cubic-quintic nonlinear Schrödinger equation can describe atmospheric plasmoids at the initial stages of their evolution. Note that, besides the modeling of atmospheric plasma structures, my results can be applied for the explanation of the results of experiments where long-lived glowing plasmoids weere obtained in electric discharges in liquid nitrogen.
We consider Dirac neutrinos interacting with background fermions in the frame of the standard model. We demonstrate that a time-dependent effective potential is quite possible in a protoneutron star (PNS) at certain stages of its evolution. For the first time, we formulate a nonperturbative treatment of neutrino processes in a matter with arbitrary time-dependent effective potential. Using linearly growing effective potential, we study the typical case of a slowly varying matter interaction potential. We calculate differential mean numbers of $ν\barν$ pairs created from the vacuum by this potential and find that they crucially depend on the magnitude of masses of the lightest neutrino eigenstate. These distributions uniformly span up to $\sim 10$ eV energies for muon and tau neutrinos created in PNS core due to the compression just before the hydrodynamic bounce and up to $\sim 0.1$ eV energies for all three active neutrino flavors created in the neutronization. Considering different stages of the PNS evolution, we derive constraints on neutrino masses, $m_ν\lesssim (10^{-8}-10^{-7})$ eV corresponding to the nonvanishing $ν\barν$ pairs flux produced by this mechanism. We show that one can distinguish such coherent flux from chaotic fluxes of any other origin. Part of these neutrinos, depending on the flavor and helicity, are bounded in the PNS, while antineutrinos of any flavor escape the PNS. If the created pairs are $ν_{e}\barν_{e}$, then a part of the corresponding neutrinos also escape the PNS. The detection of $ν$ and $\barν$ with such low energies is beyond current experimental techniques.
The magnetohydrodynamics (MHD) is modified to incorporate the parity violation in the Standard Model leading to a new instability of magnetic fields in the electroweak plasma in the presence of nonzero neutrino asymmetries. The main ingredient for such a modified MHD is the antisymmetric part of the photon polarization tensor in plasma, where the parity violating neutrino interaction with charged leptons is present. We calculate this contribution to the polarization tensor connected with the Chern-Simons term in effective Lagrangian of the electromagnetic field. The general expression for such a contribution which depends on the temperature and the chemical potential of plasma as well as on the photon's momentum is derived. The instability of a magnetic field driven by the electron neutrino asymmetry for the $ν$-burst during the first second of a supernova explosion can amplify a seed magnetic field of a protostar, and, perhaps, can explain the generation of strongest magnetic fields in magnetars. The growth of a cosmological magnetic field driven by the neutrino asymmetry density $Δn_ν=n_ν - n_{\barν}\neq 0$ is provided by a lower bound on $|ξ_{ν_e}|=|μ_{ν_e}|/T$ which is consistent with the well-known Big Bang nucleosynthesis (upper) bound on neutrino asymmetries in a hot universe plasma.
We study stable axially and spherically symmetric spatial solitons in plasma with diatomic ions. The stability of a soliton against the collapse is provided by the interaction of induced electric dipole moments of ions with rapidly oscillating electric field of a plasmoid. We derive the new cubic-quintic nonlinear Schrodinger equation which governs the soliton dynamics and numerically solve it. Then we discuss the possibility of implementation of such plasmoids in realistic atmospheric plasma. In particular, we suggest that spherically symmetric Langmuir solitons, described in the present work, can be excited at the formation stage of long-lived atmospheric plasma structures. The implication of our model for the interpretation of the results of experiments for the plasmoids generation is discussed.
We derive the new quasi-classical equation for the description of the spin evolution of a neutrino propagating in a curved space-time and interacting with a background matter and an external electromagnetic field. This equation is used to analyze neutrino spin oscillations in these external backgrounds. We obtain the effective Hamiltonian and the transition probability for oscillations of neutrinos when they move in the vicinity of a rotating black hole, surrounded by an accretion disk, and interact with an external magnetic field. The appearance of new resonances in neutrino spin oscillations in this system is considered. The approximate treatment of spin oscillations of radially propagating ultra high energy neutrinos is developed. We also discuss the applications of our results to the description of neutrino spin oscillations in realistic astrophysical media.
We briefly review the main methods for the description of massive Weyl fields in vacuum. On the classical level we discuss Weyl fields expressed through Grassmann variables as well as having spinors with commuting components. In both approaches we quantize the system. We get the correct anticommutation relations between creation and annihilation operators, which result in the proper form of the total energy of the field. However, the commuting classical Weyl fields require the new method of quantization.