arXiv subjects

G. A. Koroteev

Publications and source records attributed to G. A. Koroteev.

10 recordsLinked to original sources

arXiv2026

Interaction of accelerator neutrinos with energies up to 55 MeV with ${}^{127}$I nuclei

The interaction of neutrinos with an energy of up to 55~MeV from the Spallation Neutron Source (SNS) accelerator with a perspective ${}^{127}$I detector at the Oak Ridge National Laboratory (United States) has been studied. The resonance structure of the charge-exchange strength function $S(E)$ has been calculated taking into account high-lying resonances, and the effect of this structure on the cross section $σ(E)$ for the accelerator neutrino capture by the ${}^{127}$I nucleus has been examined. The influence of the Gamow-Teller resonance GTR-1 and the second new higher resonance GTR-2 on the energy dependence of the cross section $σ(E)$ has been analyzed. The effect of the high-lying analog resonance AR-2 has also been taken into account for the first time. It has been found that the contributions of GTR-1 to the calculated cross section $σ(E)$ are from 60% to $\approx$80%, and GTR-2 about 12%, and AR-2 $\le$ 10%, respectively. The contribution of high-lying resonances to the $(ν, n)$ and $(ν, 2n)$ neutrino capture cross sections with neutron emission and the formation of the ${}^{126}$I and ${}^{125}$I isotopes, respectively, has been analyzed. The comparison of the cross sections for the interaction of accelerator neutrinos calculated by different methods with experimental data has shown coincidence at energies below the neutron separation threshold $E_x < S_{1n}$ and strong discrepancy at higher energies, which is difficult to explain. A new measurement of cross sections at energies $E_x > S_{1n}$ is needed.

nucl-th↗

arXiv2026

Real Matrix Representations of Quantum Operators: An Introduction to Quantum Index Algebra

We introduce Quantum Index Algebra (QIA) as a finite, index-based algebraic framework for representing and manipulating quantum operators on Hilbert spaces of dimension $2^m$. In QIA, operators are expressed as structured combinations of basis elements indexed by Boolean codes, allowing products, commutators, and conjugations to be computed through finite rules on discrete indices rather than through dense matrix arithmetic. This representation unifies combinatorial index structure, explicit matrix realization, and transformation properties under Walsh-Hadamard-type transforms within a single formalism. Using QIA and its associated block-matrix realization, we reformulate the Bernstein-Vazirani hidden-string problem in its phase-oracle form entirely within a real, finite-dimensional algebraic setting. We show that, under structured oracle access, the QIA procedure reproduces the Bernstein-Vazirani algorithm exactly and achieves the same asymptotic query complexity and circuit depth as the standard quantum algorithm. In particular, the hidden string is recovered by symbolic manipulation of a sparse algebraic representation of the oracle rather than by numerical simulation of quantum amplitudes. Our results demonstrate that the apparent quantum speed-up in this setting is a consequence of operator structure rather than Hilbert-space dimensionality alone. QIA thus provides a precise language for separating genuinely quantum resources from those arising from algebraic and combinatorial structures and offers a new perspective on the classical simulability of structured quantum circuits.

quant-ph↗

arXiv2025

Bell, Spinors, and the Impossibility of a Classical Spin-Vector Model

We revisit the Bell--CHSH scenario for two spin-$\tfrac{1}{2}$ particles and isolate the precise algebraic origin of the Bell contradiction. On the quantum side, spin-$\tfrac{1}{2}$ is described by a noncommutative spinor (Clifford) algebra acting on the Hilbert space of two spin-$\tfrac{1}{2}$ particles, with the singlet state yielding the usual correlation $E(a,b) = -\,a\cdot b$ and Tsirelson's bound $2\sqrt{2}$. On the classical side, the standard Bell assumptions amount to describing all measurement outcomes as $\{\pm1\}$-valued random variables on a single Kolmogorov probability space, i.e.\ elements of a commutative algebra $\mathcal{C}(Λ)$. We show that there is no representation of the spinor algebra of spin-$\tfrac{1}{2}$ (with its singlet state and locality structure) into any such commutative Kolmogorov algebra that preserves the $\{\pm1\}$ spectra of local spin components and the singlet correlations entering the CHSH expression, under the standard Bell assumptions of locality (factorization) and measurement independence. In this sense, the Bell--CHSH contradiction is exhibited as an algebraic mismatch between a noncommutative spinor/Clifford description of spin and the classical assumption of a single global Kolmogorov space supporting all outcomes. In the language of quantum probability, this is a C$^*$-algebraic reformulation of the known fact that the singlet correlations admit no local hidden-variable model with jointly distributed outcomes on one probability space. We also give an explicit realization of the same spinor structure within the author's Quantum Index Algebra (QIA) framework, where locality appears as disjoint index slots and the singlet state as a simple index cocycle.

quant-ph↗

arXiv2024

Solar neutrino capture by 128, 130Te isotopes and Baksan Large Neutrino Telescope Project

This paper discusses the charge-exchange strength functions $S(E)$ of the isotopes $^{128,130}$Te. The experimental data of the $S(E)$ strength functions obtained from $(^{3}\mathrm{He}, t)$ reactions, as well as the $S(E)$ strength functions calculated in the microscopic theory of finite fermi-systems, are analyzed. The resonance structure of the strength function $S(E)$ is examined, and the Gamow-Teller and Pygmy resonances are identified. The resonance structure of the strength function $S(E)$ is vital for the calculation and analysis of the process of neutrino capture by atomic nuclei.

nucl-th↗

arXiv2023

Interaction of solar neutrinos with $^{98,100}$Mo isotopes and the influence of nuclear resonances

The process of neutrino interaction with $^{98}$Mo and $^{100}$Mo isotopes is studied taking into consideration the effect of charge-exchange resonances. The experimental data on the strength functions $S(E)$ obtained in charge-exchange reactions $(p; n)$ and $(^3\mathrm{He}, t)$ and the strength functions $S(E)$ calculated within the theory of finite Fermi systems were used. We studied the effect of the resonance structure of $S(E)$ on the cross sections for solar-neutrino. We investigated the contribution of each high-lying resonance to the capture cross section $σ(E_ν)$. The contributions of all components of the solar neutrino spectrum are calculated. We estimate the contribution of different components of solar neutrinos as the background for the double-beta decay experiments on $^{100}$Mo.

nucl-th↗

arXiv2021

Cross sections of solar neutrino capture by 127I nuclei and Gamow Teller resonances

Solar neutrino capture cross-section by 127I nucleus has been studied with taking into account the influence of the resonance structure of the nuclear strength function S(E). Three types of isobaric resonances: giant Gamow-Teller, analog resonance and low-lying Gamow-Teller pigmy resonances has been investigated on the framework of self-consistent theory of finite Fermi systems. The calculations have been performed considering the resonance structure of the charge-exchange strength function S(E). We analyze the effect of each resonance on the energy dependence of the cross-section. It has been shown that all high-lying resonances should be considered. Neutron emission process for high energy nuclear excitation leads to formation 126Xe isotope. We evaluate contribution from various sources of solar neutrinos to the 126Xe/127Xe isotopes ratio formed by energetic neutrinos. 126Xe/127Xe isotope ratio could be an indicator of high-energy boron neutrinos in the solar spectrum. We also discuss the uncertainties in the often used Fermi-functions calculations.

nucl-th↗

arXiv2018

Resonances in the solar neutrino capture cross-section for $ ^{76}Ge $ nuclei

The calculation results of solar neutrino capture cross-section on the $^{76}Ge$ nucleus are presented. The charge-exchange strength function $S(E)$ was obtained from the experiment data in the $ ^{76}Ge(^{3}He, t)^{76}As $ reaction. The calculation includes the effect of the resonant structure of the strength function $S(E)$ on the calculated cross section $σ(E_ν)$. It is shown that only the giant Gamow-Teller resonance contributes about 20%, and an even greater contribution is made by excited states located lower in the continuous part of the spectrum. These contributions should be taken into account in the calculation of background events in experiments on double beta decay of the GERDA type (for example LEGEND).

nucl-ex↗

arXiv2017

First measeurements in search for keV-sterile neutrino in tritium beta-decay by Troitsk nu-mass experiment

We present the first measurements of tritium beta-decay spectrum in the electron energy range 16-18.6 keV. The goal is to find distortions which may correspond to the presence of a heavy sterile neutrinos. A possible contribution of this kind would manifest itself as a kink in the spectrum with a similar shape but with end point shifted by the value of a heavy neutrino mass. We set a new upper limits to the neutrino mixing matrix element U^2_{e4} which improve existing limits by a factor from 2 to 5 in the mass range 0.1-2 keV.

hep-ex↗

arXiv2016

Electron scattering on hydrogen and deuterium molecules at 14-25 keV by the "Troitsk nu-mass" experiment

We've performed precise measurements of electron scattering on molecular hydrogen and deuterium by using the "Troitsk nu-mass" setup. Electrons were generated by the electron gun with an energy line width better than 0.3 eV. The electron energies were 14, 17, 18.7, 19 and 25 keV. The windowless gaseous tritium source (WGTS) was filled by hydrogen isotopes and served as a target. The total column density was adjusted to form a length of 0.35--0.7 of the electron mean free path. The integral spectrum of scattered electrons was measured by the electrostatic spectrometer with a magnetic adiabatic collimation and relative energy resolution 8.3 10^{-5}. As a result, the shapes of molecular excitation and ionization spectra were extracted for both isotopes. We did not find any difference between hydrogen and deuterium targets. The relative energy dependence was extracted too.

physics.ins-det↗

arXiv2015

The current status of "Troitsk nu-mass" experiment in search for sterile neutrino

We propose a new experiment to search for a sterile neutrino in a few keV mass range at the "Troitsk nu-mass" facility. The expected signature corresponds to a kink in the electron energy spectrum in tritium beta-decay. The new goal compared to our previous experiment will be precision spectrum measurements well below end point. The experimental installation consists of a windowless gaseous tritium source and a high resolution electromagnetic spectrometer. We estimate that the current bounds on the sterile neutrino mixing parameter can be improved by an order of magnitude in the mass range under 5 keV without major upgrade of the existing equipment. Upgrades of calibration, data acquisition and high voltage systems will allow to improve the bounds by another order of magnitude.

physics.ins-det↗