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A. I. Studenikin

Publications and source records attributed to A. I. Studenikin.

15 recordsLinked to original sources
arXiv2022

Quantum spin-flavour memory of ultrahigh-energy neutrino

There are two types of uncertainties related to the measurements done on a quantum system: statistical and those related to non-commuting observables and incompatible measurements. The latter indicates the quantum system's inherent nature and is in the scope of the present study. We explore uncertainties related to the interstellar ultrahigh-energy neutrino and introduce a novel concept: quantum spin-flavour memory. Advanced uncertainty measures are entropic measures, and the effect of the quantum memory reduces the uncertainty. The problem in question corresponds to a real physical event: high-energy Dirac neutrinos emitted by some distant source and propagating towards the earth. The neutrino has a finite magnetic moment and interacts with both deterministic and stochastic interstellar magnetic fields. To describe the effect of a noisy environment, we exploit the Lindblad master equation for the neutrino density matrix. Quantum spin-flavour memory we quantify in terms of the generalized Kraus's trade-off relation. This trade-off relation converts to the equality when quantum memory is absent. We discovered that while most measures of quantum correlations show their irrelevance, the quantum spin-flavour discord is the quantifier of the quantum spin-flavour memory.

quant-ph↗
arXiv2020

Coherence and mixedness of neutrino oscillations in a magnetic field

The radical departure from classical physics implies quantum coherence, i.e., coherent superposition of eigenstates of Hermitian operators with a discrete spectrum. In resource theory, quantum coherence is a resource for quantum operations. Typically the stochastic phenomenon induces decoherence effects. However, in the present work, we prove that nonunitary evolution leads to the generation of quantum coherence in some cases. Specifically, we consider the neutrino propagation in the dissipative environment, namely in a magnetic field with a stochastic component, and focus on neutrino flavor, spin and spin-flavor oscillations. We present exact analytical results for quantum coherence in neutrino oscillations quantified in terms of the relative entropy. Starting from an initial zero coherence state, we observe persistent oscillations of coherence during the dissipative evolution. We found that after dissipative evolution, the initial spin-polarized state entirely thermalizes, and in the final steady state, the spin-up/down states have the same probabilities. On the other hand, neutrino flavor states also thermalize, byt the populations of two flavor states do not equate to each other. The initial flavor still dominates in the final steady state

hep-ph↗
arXiv2020

Quantum witness and invasiveness of cosmic neutrino measurements

Measurements of cosmic neutrinos have a reach potential for providing an insight into fundamental neutrino properties. For this a precise knowledge about an astrophysical environment of cosmic neutrinos propagation is needed. However this is not always possible, and the lack of information can bring about theoretical uncertainties in our physical interpretation of the results of experiments on cosmic neutrino fluxes. We formulate an approach that allows one to quantify the uncertainties using the apparatus of quantum measurement theory. We consider high-energy Dirac neutrinos emitted by some distant source and propagating towards the earth in the interstellar space. It is supposed that neutrinos can meet on their way to the detector at the earth a dense cosmic object serving as a filter that stops active, left-handed neutrinos and letting only sterile, right-handed neutrinos to propagate further. Such a filter mimics the strongest effect on the neutrino flux that can be induced by the cosmic object and that can be missed in the theoretical interpretation of the lab measurements due to the insufficient information about the astrophysical environment of the neutrino propagation. Treating the neutrino interaction with the cosmic object as the first, neutrino-spin measurement, whose result is not recorded, we study its invasive effect on the second, neutrino-flavor measurement in the lab.

hep-ph↗
arXiv2020

Neutrino Charge Radii from COHERENT Elastic Neutrino-Nucleus Scattering

Coherent elastic neutrino-nucleus scattering is a powerful probe of neutrino properties, in particular of the neutrino charge radii. We present the bounds on the neutrino charge radii obtained from the analysis of the data of the COHERENT experiment. We show that the time information of the COHERENT data allows us to restrict the allowed ranges of the neutrino charge radii. We also obtained for the first time bounds on the neutrino transition charge radii, which are quantities beyond the Standard Model.

hep-ph↗
arXiv2019

Potentialities of a low-energy detector based on $^4$He evaporation to observe atomic effects in coherent neutrino scattering and physics perspectives

We propose an experimental setup to observe coherent elastic neutrino-atom scattering (CE$ν$AS) using electron antineutrinos from tritium decay and a liquid helium target. In this scattering process with the whole atom, that has not beeen observed so far, the electrons tend to screen the weak charge of the nucleus as seen by the electron antineutrino probe. The interference between the nucleus and the electron cloud produces a sharp dip in the recoil spectrum at atomic recoil energies of about 9 meV, reducing sizeably the number of expected events with respect to the coherent elastic neutrino-nucleus scattering case. We estimate that with a 60 g tritium source surrounded by 500 kg of liquid helium in a cylindrical tank, one could observe the existence of CE$ν$AS processes at 3$σ$ in 5 years of data taking. Keeping the same amount of helium and the same data-taking period, we test the sensitivity to the Weinberg angle and a possible neutrino magnetic moment for three different scenarios: 60 g, 160 g, and 500 g of tritium. In the latter scenario, the Standard Model (SM) value of the Weinberg angle can be measured with a statistical uncertainty of $\sin^2{\vartheta_W^{\mathrm{SM}}}^{+0.015}_{-0.016}$. This would represent the lowest-energy measurement of $\sin^2{\vartheta_W}$, with the advantage of being not affected by the uncertainties on the neutron form factor of the nucleus as the current lowest-energy determination. Finally, we study the sensitivity of this apparatus to a possible electron neutrino magnetic moment and we find that using 60 g of tritium it is possible to set an upper limit of about $7\times10^{-13}\,μ_B$ at 90% C.L., that is more than one order of magnitude smaller than the current experimental limit.

hep-ph↗
arXiv2014

On sensitivity of neutrino-helium ionizing collisions to neutrino magnetic moments

We consider theoretically ionization of a helium atom by impact of an electron antineutrino. The sensitivity of this process to neutrino magnetic moments is analyzed. In contrast to the recent theoretical prediction, no considerable enhancement of the electromagnetic contribution with respect to the free-electron case is found. The stepping approximation is shown to be well applicable practically down to the ionization threshold.

hep-ph↗
arXiv2011

New bounds on neutrino magnetic moment and re-examination of plasma effect in neutrino spin light

Recent discussion on the possibility to obtain more stringent bounds on neutrino magnetic moment has stimulated new interest to possible effects induced by neutrino magnetic moment. In particular, in this note after a short review on neutrino magnetic moment we re-examine the effect of plasmon mass on neutrino spin light radiation in dense matter. We track the entry of the plasmon mass quantity in process characteristics and found out that the most substantial role it plays is the formation of the process threshold. It is shown that far from this point the plasmon mass can be omitted in all the corresponding physical quantities and one can rely on the results of massless photon spin light radiation theory in matter.

hep-ph↗
arXiv2011

Testing neutrino magnetic moment in ionization of atoms by neutrino impact

The atomic ionization processes induced by scattering of neutrinos play key roles in the experimental searches for a neutrino magnetic moment. Current experiments with reactor (anti)neutrinos employ germanium detectors having energy threshold comparable to typical binding energies of atomic electrons, which fact must be taken into account in the interpretation of the data. Our theoretical analysis shows that the so-called stepping approximation to the neutrino-impact ionization is well applicable for the lowest bound Coulomb states, and it becomes exact in the semiclassical limit. Numerical evidence is presented using the Thomas-Fermi model for the germanium atom.

hep-ph↗
arXiv2008

Spin Effects for Neutrinos and Electrons Moving in Dense Matter

We shortly summarize the present status of neutrino magnetic moment studies (theory and experiment). Then we discuss the quasiclassical treatment of neutrino spin evolution in matter. After that we come to the quantum approach to description of neutrino and electron motion in matter on the basis of the quantum wave equations exact solutions method with special focus on spin effects.

hep-ph↗
arXiv2002

Relativistic Treatment of Neutrino Oscillations in Moving Matter

A review on the Lorentz invariant treatment of neutrino spin and flavour oscillations in moving and polarized matter is presented. Within this approach it becomes possible to consider neutrino oscillations in arbitrary electromagnetic fields. It is also shown that neutrino effective potential in matter can be significantly changed by relativistic motion of matter.

hep-ph↗
arXiv2001

Parametric Resonance Amplification of Neutrino Oscillations in Electromagnetic Wave with Varying Amplitude and "Castle Wall" Magnetic Field

Within the Lorentz invariant formalizm for description of neutrino evolution in electromagnetic fields and matter we consider neutrino spin oscillations in the electromagnetic wave with varying amplitude and in "castle wall" magnetic field. It is shown for the first time that the parametric resonances of neutrino oscillations in such systems can occur.

hep-ph↗
arXiv2000

Neutrino Oscillations in Electromagnetic Fields

Oscillations of neutrinos $ν_L \leftrightarrow ν_R$ in presence of an arbitrary electromagnetic field are considered. We introduce the Hamiltonian for the neutrino spin evolution equation that accounts for possible effects of interaction of neutrino magnetic $μ$ and electric $ε$ dipole moments with the transversal (in respect to the neutrino momentum) and also the longitudinal components of electromagnetic field. Using this Hamiltonian we predict the new types of resonances in the neutrino oscillations $ν_L \leftrightarrow ν_R$ in the presence of the field of an electromagnetic wave and in combination of an electromagnetic wave and constant magnetic field. The possible influence of the longitudinal magnetic field on neutrino oscillations is emphasized.

hep-ph↗
arXiv2000

Electromagnetic Neutrino Properties and Neutrino Oscillations in Electromagnetic Fields

The presence of medium and external magnetic field change electromagnetic properties of neutrino. In this article the behavior of neutrino magnetic moment in electromagnetic field is considered. On the basis the Bargmann-Michel-Telegdi equation for the case of models with CP invariance and P nonconservation the new type of neutrino resonances $ν_L \leftrightarrow ν_R$ in the electromagnetic field is predicted.

hep-ph↗
arXiv1995

NEUTRINO SPIN AND FLAVOUR CONVERSION AND OSCILLATIONS IN MAGNETIC FIELD

A review of the neutrino conversion and oscillations among the two neutrino species (active and sterile) induced by strong twisting magnetic field is presented and implications to neutrinos in neutron star, supernova, the Sun and interstellar galactic media are discussed. The ``cross-boundary effect" (CBE) (i.e., a possible conversion of one half of neutrinos of the bunch from active into sterile specie) at the surface of neutron star is also studied for a realistic neutron star structure.

astro-ph↗