arXiv subjects

N. A. Petrov

Publications and source records attributed to N. A. Petrov.

7 recordsLinked to original sources

arXiv2026

Neutral kaon mass measurement with the CMD-3 derector at VEPP-2000

Using more than 600 thousand $K_{S}^{0}\toπ^{+}π^{-}$ decays from the $e^{+}e^{-}\toϕ(1020)\to K_{S}^{0}K_{L}^{0}$ reaction, the neutral kaon mass has been measured with the CMD-3 detector at the VEPP-2000 collider. Using the beam energies control by the back-scattering laser light photons, and a calibration to the world average $ϕ$-meson mass, the neutral kaon mass is determind to be m($K^0$) = 497.587 $\pm$ 0.004(stat.) $\pm$ 0.008(syst.) $\pm$ 0.009(calibr.) \mevcc, where the first uncertainty is statistical, the second is systematic, and the third is the uncertainty from the energy calibration.

hep-ex↗

arXiv2026

Study of the proccess $e^+e^-\to π^+π^-π^0π^0η$ in the c.m. energy range 1.6--2.0 GeV with the CMD-3 detector

The cross section of the process $e^+e^- \to π^+π^-π^0π^0η$ has been measured using a data sample with the integrated luminosity of 372 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider. 6300$\pm$145 signal events have been selected in the center-of-mass energy range 1.6--2.0 GeV. The total systematic uncertainty of the cross section is about 10\%. The production dynamics is dominated by the $ω(782)π^0η$ final state with a possible small contribution of the $a_0(980)$ resonance in the $π^0η$ combination. We also observe a presence of the $ρ(770)^{\pm}$ resonance signal in the $π^{\pm}π^0$ invariant mass distribution.

hep-ex↗

arXiv2026

Evidence of the $e^+ e^-\to f_1(1285)$ reaction with the CMD-3 detector at VEPP-2000

A search for the $e^+ e^-\to f_1(1285)$ reaction is performed with the CMD-3 detector at the VEPP-2000 collider. Data from a scan in the center-of-mass energy range Ec.m.=1.20--1.36 GeV with 109.1 pb$^{-1}$ of the integrated luminosity is used. A dedicated 51.7 pb$^{-1}$ have been collected at the $f_1(1285)$ resonance peak energy Ec.m.=1282 MeV, where $26.5 \pm 7.4$ events have been found in the $e^+ e^-\toηπ^0π^0$ reaction. No indication of the signal is observed in the scan data. We interpret the result as 4.5$σ$ evidence of the C-even resonance production in the $e^+ e^-\to f_1(1285)\toηπ^0π^0$ reaction via the two-photon interaction. The production cross section is found to be $σ(e^+ e^-\to f_1) = 0.074 \pm 0.021 \pm 0.010$ nb, and the corresponding branching fraction to the $e^+ e^-$ pair is $B(f_1(1285)\to e^+e^-) = (8.3 \pm 2.3 \pm 1.1)\times 10^{-9}$.

hep-ex↗

arXiv2026

Cosmic-ray anisotropy: sensitivity of methods and implications for KASCADE data

We study the problem of measuring the anisotropy of high-energy cosmic rays across all angular scales. The limited field of view and non-uniform exposure of ground-based cosmic-ray experiments reduce their sensitivity to real anisotropy of cosmic-ray arrival directions. A widely used signature of anisotropy -- a dipole of the flux expansion over the right ascension -- provides very limited understanding of the underlying physics of cosmic-ray origin and propagation. In this study we test two other methods: the angular power spectrum and the autocorrelation function for sensitivity to possible medium- and small-scale anisotropies of cosmic-ray flux. We find that the autocorrelation function is the most sensitive estimator for an underlying physical anisotropy in most of the models tested, while the angular power spectrum can provide additional knowledge about cosmic-ray flux properties, when the anisotropy is strong enough. As a test of our findings, we apply these methods to $10\%$ sample of the KASCADE experiment public data. Namely, we consider all-particle set of events and sets of individual mass groups classified by a convolutional neural network. We find an indication of anisotropy at $> 2.5 σ$ level at $\sim 10^\circ$ angular scale for the iron nuclei mass group at $E \gtrsim 20$ PeV with both the angular power spectrum and the autocorrelation methods.

astro-ph.HE↗

arXiv2026

Ultra-high energy event KM3-230213A as a cosmogenic neutrino in light of minimal UHECR flux models

Recently, the KM3NeT experiment reported the detection of a neutrino with exceptionally high energy E = 220 PeV, whose origin remains unclear. The corresponding value of the neutrino flux is in tension with the results of other high-energy neutrino experiments. In this study, we discuss the possibility that this neutrino is cosmogenic, i. e., produced by ultra-high energy cosmic rays (UHECR) during their propagation through the intergalactic medium. We adopt the UHECR flux models derived by the Telescope Array experiment, which features a predominantly light mass composition. We show that the predictions of the cosmogenic neutrino flux in these models are consistent with the measurements of the KM3NeT-only and with that of the "global neutrino observatory" at approximately 2$σ$ level. Notably, this result is achieved in a minimal version of the UHECR flux models, that assume one source population with a standard cosmological evolution. We also estimate the corresponding cosmogenic gamma-ray flux and show that it is consistent with Fermi-LAT IGRB measurements and UHE gamma-ray limits; the improvement of the latter can probe these predictions in future.

astro-ph.HE↗

arXiv2024

Energy spectra of elemental groups of cosmic rays with the KASCADE experiment data and machine learning

We report the reconstruction of the mass component spectra of cosmic rays (protons, helium, carbon, silicon and iron) and their mean mass composition, at energies from 1.4 to 100 PeV. The results are derived from the archival data of the extensive air shower experiment KASCADE. We use a novel machine learning technique developed specifically for this reconstruction, and post-LHC hadronic interaction models: QGSJet-II.04, EPOS-LHC and Sibyll 2.3c. We have found an excess of the proton component and a deficit of intermediate and heavy nuclei components compared to the original KASCADE results. The spectra of protons and helium show a knee-like behavior at ~ 4.4 PeV and ~ 11 PeV, with significances 5.2$σ$ and 3.9$σ$, respectively. The spectrum of the iron component has a hint (2.4$σ$) of a hardening at ~ 4.5 PeV, which can be interpreted as a counterpart of a hardening in the proton spectrum at 166 TeV, recently reported by the GRAPES-3 experiment. The systematic uncertainties of our analysis were found to be smaller than those of the original KASCADE, as well as those of IceTop and TALE experiments, over the most part of the energy range studied. We also estimated separately the uncertainty related to the difference between the three mentioned hadronic interaction models. We also compute a mean logarithm mass of cosmic ray flux as a function of energy. It is in agreement with the results of IceTop, TALE and LHAASO within the uncertainties.

astro-ph.HE↗

arXiv2023

Methods of machine learning for the analysis of cosmic rays mass composition with the KASCADE experiment data

We study the problem of reconstruction of high-energy cosmic rays mass composition from the experimental data of extensive air showers. We develop several machine learning methods for the reconstruction of energy spectra of separate primary nuclei at energies 1-100 PeV, using the public data and Monte-Carlo simulations of the KASCADE experiment from the KCDC platform. We estimate the uncertainties of our methods, including the unfolding procedure, and show that the overall accuracy exceeds that of the method used in the original studies of the KASCADE experiment.

astro-ph.HE↗