Searcharxiv⌕ Search

arXiv subjects

Alexander Studenikin

Publications and source records attributed to Alexander Studenikin.

At least 55 records · Page 3Linked to original sources
arXiv2019

Neutrino eigenstates and flavour, spin and spin-flavour oscillations in a constant magnetic field

We further develop a recently proposed new approach to the description of the relativistic neutrino flavour $ν_e^L \leftrightarrow ν_μ^L$, spin $ν_e^L \leftrightarrow ν_{e}^R$ and spin-flavour $ν_e^L \leftrightarrow ν_μ^R$ oscillations in a constant magnetic field that is based on the use of the exact neutrino stationary states in the magnetic field. The neutrino flavour, spin and spin-flavour oscillations probabilities are calculated accounting for the whole set of possible conversions between four neutrino states. In general, the obtained expressions for the neutrino oscillations probabilities exhibit new inherent features in the oscillation patterns. It is shown, in particular, that: 1) in the presence of the transversal magnetic field for a given choice of parameters (the energy and magnetic moments of neutrinos and the strength of the magnetic field) the amplitude of the flavour oscillations $ν_e^L \leftrightarrow ν_μ^L$ at the vacuum frequency is modulated by the magnetic field frequency, 2) the neutrino spin oscillation probability (without change of the neutrino flavour) exhibits the dependence on the mass square difference $Δm^2$. It is shown that the discussed interplay of neutrino oscillations in magnetic fields on different frequencies can have important consequences in astrophysical environments, in particular in those peculiar for magnetars.

hep-ph↗
arXiv2019

Neutrino spin and spin-flavour oscillations in transversal matter currents with standard and non-standard interactions

After a brief history of two known types of neutrino mixing and oscillations, including neutrino spin and spin-flavour oscillations in the transversal magnetic field, we perform systematic study of a new phenomenon of neutrino spin and spin-flavour oscillations engendered by the transversal matter currents on the bases of the developed quantum treatment of the phenomenon. Possibilities for the resonance amplification of these new types of oscillations by the longitudinal matter currents and longitudinal magnetic fields are analyzed. Neutrino spin-flavour oscillations engendered by the transversal matter currents in the case of non-standard interactions of neutrinos with background matter are also considered

hep-ph↗
arXiv2019

Neutrino oscillations and exact eigenstates in magnetic field

We further develop a recently proposed new approach to the description of the relativistic neutrino flavour $ν_e^L \leftrightarrow ν_μ^L$, spin $ν_e^L \leftrightarrow ν_{e}^R$ and spin-flavour $ν_e^L \leftrightarrow ν_μ^R$ oscillations in a constant magnetic field that is based on the use of the exact neutrino stationary states in the magnetic field. The neutrino flavour, spin and spin-flavour oscillations probabilities are calculated accounting for the whole set of possible conversions between four neutrino states. In general, the obtained expressions for the neutrino oscillations probabilities exhibit new inherent features in the oscillation patterns. It is shown, in particular, that: 1) in the presence of the transversal magnetic field for a given choice of parameters (the energy and magnetic moments of neutrinos and the strength of the magnetic field) the amplitude of the flavour oscillations $ν_e^L \leftrightarrow ν_μ^L$ at the vacuum frequency is modulated by the magnetic field frequency, 2) the neutrino spin oscillation probability (without change of the neutrino flavour) exhibits the dependence on the mass square difference $Δm^2$.

hep-ph↗
arXiv2018

Neutrino electromagnetic properties: a window to new physics - II

There is merely a short note on the selected issues of neutrino electromagnetic properties with focus on effects of new physics. The meaning of "new physics" is twofold: 1) a massive neutrino have nonzero electromagnetic properties that can be considered as manifestation of new physics beyond the Standard Model, and 2) in studies of neutrinos electromagnetic interactions new effects are predicted that can lead to new phenomena accessible for observations.

hep-ph↗
arXiv2018

On possible application of spin light of neutrino in astrophysics

The $ spin $ $ light$ $ of $ $neutrino $ ($SLν$) is a phenomenon of electromagnetic radiation by a massive neutrino moving in external media that is originated owing to neutrino magnetic moment. In this short paper we note on the importance of this effect in the light of its connection with the neutrino magnetic moment, recap its basic properties in dense matter and give some general criteria for its best efficiency in nature. On this basis we propose a set of possible astrophysical environments where the $SLν$ can be manifested in principle.

hep-ph↗
arXiv2018

Neutrino quantum decoherence due to entanglement with magnetic field

The phenomena of neutrino oscillations emerges due to coherent superposition of different neutrino states. The entanglement of neutrinos with its environment can lead to a suppression of neutrino oscillations. The master equation for neutrino evolution in a magnetic field is derived taking into account the entanglement with a magnetic field.

hep-ph↗
arXiv2018

Neutrino motion and spin oscillations in magnetic field and matter currents

A brief review of a neutrino oscillations effect in an external magnetic field and matter currents is given. An ultra-relativistic neutrino propagation in moving external media is investigated. We have found a new spin operator which commutes with the corresponding Hamiltonian, exact wave functions and energy spectrum are obtained.

hep-ph↗
arXiv2017

From neutrino electromagnetic interactions to spin oscillations in transversal matter currents

Massive neutrinos have nonzero magnetic moments. It is known that the neutrino spin oscillations can be induced by the neutrino magnetic moment interaction with the transversal magnetic field. We perform a regions derivation of the effective neutrino evolution Hamiltonian in moving matter and show that spin oscillations can be engendered by the interaction with the transversal current of matter. The obtained general expression for the neutrino effective evolution Hamiltonian can be used for investigations of various types of neutrino spin oscillations in the transversal matter currents considered in the neutrino mass and flavour basis.

hep-ph↗
arXiv2017

Spin light of neutrino in astrophysical environments

The ${\it {spin \ \ light \ \ of \ \ neutrino}}$ ($SLν$) is a new possible mechanism of electromagnetic radiation by a massive neutrino (with a nonzero magnetic moment) moving in media. Since the prediction of this mechanism, the question has been debated in a number of publications as whether the effect can be of any significance for realistic astrophysical conditions. Although this effect is strongly suppressed due to smallness of neutrino magnetic moment, for ultra-high energy neutrinos (PeV neutrinos recently observed by the IceCube collaboration, for instance) the $SLν$ might be of interest in the case of neutrinos propagating in dense matter. An advanced view on the $SLν$ in matter is given, and several astrophysical settings (a neutron star, supernova, Gamma-Ray Burst (GRB), and relic neutrino background) for which the effect can be realized are considered. Taking into account the threshold condition and also several competing processes, we determine conditions for which the $SLν$ mechanism is possible. We conclude that the most favorable case of the effect manifestation is provided by ultra dense matter of neutron stars and ultrahigh energy of the radiating neutrino, and note that these conditions can be met within galaxy clusters. It is also shown that due to the $SLν$ specific polarization properties this electromagnetic mechanism is of interest in the connection with the observed polarization of GRB emission.

hep-ph↗
arXiv2016

Neutrino spin-flavor oscillations derived from the mass basis

We consider neutrino mixing and oscillations in presence of an arbitrary constant magnetic field with nonzero transversal $B_{\perp}$ and longitudinal $B_{\parallel}$ components with respect to the direction of neutrino propagation. The electromagnetic interaction of neutrinos is determined by diagonal and transition neutrino magnetic moments that are introduced for the neutrino mass states. Explicit expressions for the effective neutrino diagonal and transition magnetic moments for the flavor basis in terms of these values for the mass states are obtained. The effective evolution Hamiltonian for the flavor neutrino and the corresponding oscillation probability are derived. The role of the longitudinal magnetic field component is examined. In particular, it is shown that: 1) $B_{\parallel}$ coupled to the corresponding magnetic moments shifts the neutrino energy, and 2) in case of nonvanishing neutrino transition magnetic moments $B_{\parallel}$ produces an additional mixing between neutrino states, both in the mass and flavor neutrino bases.

hep-ph↗
arXiv2016

Status and perspectives of neutrino magnetic moments

Basic theoretical and experimental aspects of neutrino magnetic moments are reviewed, including the present best upper bounds from reactor experiments and astrophysics. An interesting effect of neutrino spin precession and oscillations induced by the background matter transversal current or polarization is also discussed.

hep-ph↗
arXiv2015

Neutrino electromagnetic interactions: a window to new physics

We review the theory and phenomenology of neutrino electromagnetic interactions, which give us powerful tools to probe the physics beyond the Standard Model. After a derivation of the general structure of the electromagnetic interactions of Dirac and Majorana neutrinos in the one-photon approximation, we discuss the effects of neutrino electromagnetic interactions in terrestrial experiments and in astrophysical environments. We present the experimental bounds on neutrino electromagnetic properties and we confront them with the predictions of theories beyond the Standard Model.

hep-ph↗
arXiv2015

Neutrino electromagnetic properties: new approach to oscillations in magnetic fields

Several new and interesting aspects of neutrino oscillations in a magnetic field are considered: 1) We develop a standard usually used approach to the neutrino spin oscillations in the neutrino mass basis and obtain the effective neutrino spin (and "spin-mass") oscillation Hamiltonian that can be used for description of the neutrino oscillations between different pairs of neutrino states with different masses and helicities; 2) We derive the exact solution of the Dirac equation for a massive neutrino with nonzero magnetic moment in the presence of a constant transversal magnetic field that is rotating along the direction of the neutrino propagation (the twisting magnetic field) and on the basis of the obtained energy spectrum the neutrino spin oscillation effective Hamiltonian is derive; 3) We develop a new approach to neutrino spin oscillations that is based on the description of the neutrino spin states with the corresponding spin operator that commutes with the neutrino dynamics Hamiltonian in the magnetic field. The obtained new results can have important phenomenological applications.

hep-ph↗
arXiv2014

Neutrino electromagnetic properties and new physics

New effects of nontrivial neutrino electromagnetic properties are investigated on the basis of exact solutions of the modified Dirac equations for neutrinos in dense magnetized rotating matter. The effect of spatial separation of different types of neutrinos and antineutrinos (different in flavors and energies) moving inside dense magnetized rotating matter is predicted. We also describe a new mechanism of a star rotation frequency shift by neutrinos escaping the star (termed "Neutrino Star Turning" mechanism, $νS T$). The $νS T$ mechanism can explain the origin of pulsar "anti-glitches" and ordinary glitches as well. Considering a possible effect of the $νS T$ mechanism on speeding up of a pulsar together with the observational data on pulsars, we obtain a new limit on a neutrino millicharge $q_ν<1.3\times10^{-19}e_0$ that is one of the strongest limits on this value obtained in astrophysics.

hep-ph↗
arXiv2014

Millicharged neutrino with anomalous magnetic moment in rotating magnetized matter

New exact solutions of the modified Dirac equation describing a neutrino with nontrivial electromagnetic properties in extreme background conditions are obtained. Within the quasi-classical treatment the effective Lorentz force that describes the neutrino propagation in the magnetized rotating matter is introduced. We predict the effect of the spatial separation of different types of relativistic neutrinos and antineutrinos (different in flavors and energies) by the magnetized rotating matter of a star. Low energy neutrinos can be even trapped inside the star. We also predict two new phenomena: a new type of the neutrino electromagnetic radiation (termed "Light of (milli)Charged Neutrino", $LCν$) and a new mechanism of the star angular velocity shift due to neutrinos escaping the star (termed "Neutrino Star Turning" mechanism, $νS T$). The possible impact of the $νS T$ mechanism on a supernova explosion yields a new astrophysical limit on the neutrino millicharge $q_ν<1.3\times10^{-19}e_0$. In addition, the $νS T$ mechanism can be also used to explain the origin of pulsar "anti-glitches" and ordinary glitches as well.

hep-ph↗
arXiv2014

Spin light of electron in dense neutrino fluxes

An electron motion in a dense neutrino flux is investigated. The Dirac equation exact solutions for the electron energy and wave function in this external environment are obtained. On this basis we predict the existence of an electromagnetic radiation that can be emitted by electrons in dense neutrino fluxes. We term this phenomenon "the spin light of electron in dense neutrino flux" ($SLe_ν$). The main properties of the $SLe_ν$ are studied. We argue that the $SLe_ν$ in dense neutrino fluxes should have important consequences in astrophysics and for supernovae processes in particular.

hep-ph↗
arXiv2014

New bounds on neutrino electric millicharge from limits on neutrino magnetic moment

Using the new limit on the neutrino anomalous magnetic moment recently obtained by the GEMMA experiment on measurements of the cross section for the reactor antineutrino scattering on free electrons, we get a new direct upper bound on the neutrino millicharge $\mid q_ν \mid < 1.5 \times 10^{-12} e_0$. This is a factor of 2 more stringent constraint than the previous bound obtained from the TEXONO reactor experiment data that is included to the Review of Particle Properties 2012. We predict that with data from the ongoing new phase of the GEMMA experiment the upper bound on the neutrino millicharge will be reduced to $\mid q_ν \mid < 3.7 \times 10^{-13}e_0$ within two years. We also predict that with the next phase of the considered experiment the upper bound on the millicharge will be reduced by an order of magnitude over the present bound and reach the level $\mid q_ν \mid < 1.8 \times 10^{-13}e_0$ within approximately four years.

hep-ph↗