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Alexander Studenikin

Publications and source records attributed to Alexander Studenikin.

At least 37 records · Page 2Linked to original sources
arXiv2022

Neutrino magnetic moments in low-energy neutrino scattering on condensed matter systems

The cross sections of elastic neutrino scattering on electrons and nuclei in the regime of low-energy transfer are known to be very sensitive to neutrino electromagnetic properties. In particular, the magnetic moment of the neutrino can be effectively searched using liquid or solid detectors with a very low energy threshold. We present the formalism that incorporates the neutrino magnetic moment contribution in the theoretical treatment of the low-energy elastic neutrino scattering on a condensed-matter target. The concept of the dynamic structure factor is employed to describe the collective effects in the target. The differential cross section for tritium antineutrino scattering on the superfluid $^4$He is calculated numerically. We find that the neutrino magnetic moment of the order of $10^{-11}μ_B$ strongly affects the cross section. Our results can be used in the search of neutrino magnetic moments in future low-energy neutrino scattering experiments with liquid or solid targets.

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arXiv2021

Collective neutrino oscillations in moving and polarized matter

We consider neutrino evolution master equations in dense moving and polarized matter consisted of electrons, neutrons, protons and neutrinos. We also take into account the neutrino magnetic moment interaction with a magnetic field. We point out the mechanisms responsible for the neutrino spin precession and provide the expressions for the corresponding interaction Hamiltonians that should be taken into account in theoretical treatments of collective neutrino oscillations.

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arXiv2021

Collective effects in neutrino scattering on solid and liquid targets

Neutrino scattering on liquid and solid targets at low energy transfer can serve both as a tool for searching the physics beyond the Standard Model, for example, such as neutrino electromagnetic interactions, and as a test of the Standard Model at low-energy scale. At the same time, the theoretical apparatus for low-energy elastic neutrino scattering on electrons and nuclei bound in liquids and solids must take into account collective effects in the electron and nuclear subsystems of the target. We develop such an apparatus based on the formalism of the dynamic structure factor. A numerical illustration of the role of the collective effects is provided for the case of a superfluid He-4 target.

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arXiv2021

Electromagnetic neutrinos: The theory and bounds from scattering experiments

A brief overview of the electromagnetic properties of neutrinos is presented with a discussion of the most important fundamental aspects of the problem. Then using data from the ground-based reactor and solar neutrino-electron scattering experiments the best upper bounds on neutrino effective magnetic moments are discussed.

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arXiv2021

Manifestations of non-zero Majorana CP violating phases in oscillations of supernova neutrinos

We investigate effects of non-zero Dirac and Majorana CP violating phases on neutrino-antineutrino oscillations in a magnetic field of astrophysical environments. It is shown that in the presence of strong magnetic fields and dense matter, non-zero CP phases can induce new resonances in the oscillations channels $ν_e \leftrightarrow \barν_e$, $ν_e \leftrightarrow \barν_μ$ and $ν_e \leftrightarrow \barν_τ$. We also consider all other possible oscillation channels with $ν_μ$ and $ν_τ$ in the initial state. The resonances can potentially lead to significant phenomena in neutrino oscillations accessible for observation in experiments. In particular, we show that neutrino-antineutrino oscillations combined with Majorana-type CP violation can affect the $\barν_e$/$ν_e$ ratio for neutrinos coming from the supernovae explosion. This effect is more prominent for the normal neutrino mass ordering. The detection of supernovae neutrino fluxes in the future experiments, such as JUNO, DUNE and Hyper-Kamiokande, can give an insight into the nature of CP violation and, consequently, provides a tool for distinguishing the Dirac or Majorana nature of neutrinos.

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arXiv2021

Electromagnetic neutrino properties: new constraints and new effects

The electromagnetic properties of neutrinos have attracted considerable attention from researchers for many decades (see [1] for a review). However, until recently, there was no indication in favour of nonzero electromagnetic properties of neutrinos either from laboratory experiments with ground-based neutrino sources or from observations of astrophysical neutrino fluxes. The situation changed after the XENON collaboration reported [2] results of the search for new physics with low-energy electronic recoil data recorded with the XENON1T detector. The results show an excess of events over the known backgrounds in the recoil energy which, as one of the possible explanations, admit the presence of a sizable neutrino magnetic moment, the value of which is of the order of the existing laboratory limitations. In these short notes we give a brief introduction to neutrino electromagnetic properties and focus on the most important constraints on neutrino magnetic moments, charge radii and millicharges from the terrestrial experiments and astrophysical considerations. The promising new possibilities for constraining neutrino electromagnetic properties in future experiments are also discussed.

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arXiv2021

Collective neutrino oscillations accounting for neutrino quantum decoherence

In our previous studies (see [1] and references therein) we developed a new theoretical framework that enabled one to consider a new mechanism of neutrino quantum decoherence engendered by the neutrino radiative decay. In parallel, another framework was developed (see [2] and references therein) for the description of the neutrino quantum decoherence due to the non-forward neutrino scattering processes. Both mechanisms are described by the master equations in the Lindblad form. We study the influence of the neutrino quantum decoherence on collective neutrino oscillations. In the present studies we are are not interested in a specific mechanism of neutrino quantum decoherence. Therefore, we use the general Lindblad master equation for the description of the neutrino quantum decoherence and do not fix an analytical expressions for the decoherence and relaxation parameters.

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arXiv2020

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

We develop the approach to the problem of neutrino oscillations in a magnetic field introduced in \cite{Popov:2019nkr} and extend it to the case of three neutrino generations. The theoretical framework suitable for computation of the Dirac neutrino spin, flavour and spin-flavour oscillations probabilities in a magnetic field is given. It is shown that there is an entanglement between neutrino flavour and spin oscillations and in the general case it is not possible to consider these two types of neutrino oscillations separately. The closed analytic expressions for the probabilities of oscillations are obtained accounting for the normal and inverted hierarchies and the possible effect of CP violation. In particular, it is shown that the probabilities of the conversions without neutrino flavor change, i.e. $ν_e^L \rightarrow ν_e^L$ and $ν_e^L \rightarrow ν_e^R$, do not exhibit the dependence on the CP phase, while the other neutrino conversions are affected by the CP phase. In general, the neutrino oscillation probabilities exhibit quite a complicated interplay of oscillations on the magnetic $μ_ν B$ and vacuum frequencies. The obtained results are of interest in applications to neutrino oscillations under the influence of extreme astrophysical environments, for example peculiar to magnetars and supernovas, as well as in studying neutrino propagation in interstellar magnetic fields.

hep-ph↗
arXiv2020

Neutrino quantum decoherence engendered by neutrino radiative decay

A new theoretical framework, based on the quantum field theory of open systems applied to neutrinos, has been developed to describe the neutrino evolution in external environments accounting for the effect of the neutrino quantum decoherence. The developed new approach enables one to obtain the explicit expressions of the decoherence and relaxation parameters that account for a particular process, in which the neutrino participates, and also for the characteristics of an external environment and of the neutrino itself, including the neutrino energy. We have used this approach to consider a new mechanism of the neutrino quantum decoherence engendered by the neutrino radiative decay to photons and dark photons in an astrophysical environment. The importance of the performed studies is highlighted by the prospects of the forthcoming new large volume neutrino detectors that will provide new frontier in high-statistics measurements of neutrino fluxes from supernovae.

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arXiv2020

Neutrino spin and spin-flavor oscillations in matter currents and magnetic fields

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. We also consider modifications of the oscillation probabilities due to possible arbitrary orientation of the magnetic field vector ${\bf B}$ and the matter velocity ${\bf v}$.

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arXiv2019

The effect of neutrino quantum decoherence

The neutrino oscillation patterns can be modified by neutrino interactions with external environments including electromagnetic fields that can influence on neutrinos in the case neutrinos have nonzero electromagnetic properties [1]. The phenomenon of neutrino oscillations can proceed only in the case of the coherent superposition of neutrino mass states. An external environment can modify a neutrino evolution in a way that conditions for the coherent superposition of neutrino mass states are violated. Such a violation is called quantum decoherence of neutrino states and leads to the suppression of flavor neutrino oscillations [2, 3]. Note that neutrino decoherence appeared due to the wave separation of different mass states is usually not related to quantum neutrino decoherence, the effect that is not considered below. We consider the neutrino quantum decoherence due to neutrino radiative decay in the presence of an electron medium and radiation field. The corresponding damping of neutrino oscillations is calculated.

hep-ph↗
arXiv2019

Neutrino evolution and quantum decoherence

Neutrino interactions with an external environment can in influence the neutrino oscillation pattern and the oscillations can be damped as a result of the neutrino quantum decoherence. In particular, the quantum decoherence of neutrino states engendered by the neutrino radiative decay accounting for the nonstandard interactions (NSI) leads to the suppression of flavor neutrino oscillations in the solar neutrino fluxes.

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arXiv2019

New neutrino spin oscillations in moving matter and magnetic fields

After a short introduction to the history of neutrino mixing and oscillations, we celebrate the 50th anniversary of the first analytical expression for the neutrino evolution probability obtained by Gribov and Pontecorvo in 1969 by the discussion of two new phenomena in neutrino oscillations: 1) the emergence of the neutrino spin and spin-flavour oscillations engendered by the transversal in respect to neutrino propagation matter currents, and 2) an inherent interplay of neutrino oscillations on the vacuum $ω_{vac}=\frac{Δm^2}{4p}$ and magnetic $ω_{B}=μB_{\perp}$ frequencies in the case of neutrino propagation in a constance magnetics field. We also predict a new phenomena of the modification of the flavour neutrino oscillations probability in moving matter that can be engendered by a non-vanishing matter transversal current ${\bf j}_{\perp}=n {\bf v}_{\perp}$.

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arXiv2019

Neutrino oscillations and evolution in external environments: New effects

During a period of about two decades we have realized a programme of systematic investigations of different aspects of neutrino propagation in extreme external environments and have predicted and studied several new phenomena that are engendered by the presence of external magnetic fields and dense matter. The starting point that underlies the research is the fact that the electromagnetic properties of neutrinos open a window to new physics \cite{Giunti:2014ixa,Studenikin:2008bd, Studenikin:2018vnp}. In these brief notes, we recall several new phenomena that have been proposed and investigated earlier. In particular, we discuss: 1) the spin light of neutrino in matter, 2) the neutrino energy quantization in rotating matter, and 3) neutrino start turning mechanism. Then we dwell on results of recent studies: 4) the effects of interplay of neutrino flavour and spin oscillations in a magnetic field, 5) the quantum theory of neutrino spin and spin-flavour oscillations engendered by the transversal mater currents, 6) the amplitude modulation of the flavour neutrino oscillation probability by the transversal matter current. As for references to the literature, only those papers are included in which a particular effect was proposed and considered for the first time and in a number of cases references are also be given to the most recent articles, which contain detailed references to the available literature on the issue.

hep-ph↗
arXiv2019

Electromagnetic properties of neutrinos

After a brief introduction to neutrino electromagnetic properties we focus on the most important constraints on neutrino magnetic moments, charge radii and millicharges from the terrestrial experiments and astrophysical considerations. The promising new possibilities for constraining neutrino electromagnetic properties in future experiments are also discussed.

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