arXiv subjects

I. V. Obraztsov

Publications and source records attributed to I. V. Obraztsov.

11 recordsLinked to original sources

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 $e^+ e^-\to\eta\pi^0\pi^0$ reaction. No indication of the signal is observed in the scan data. We interpret the result as 4.5$\sigma$ evidence of the C-even resonance production in the $e^+ e^-\to f_1(1285)\to\eta\pi^0\pi^0$ reaction via the two-photon interaction. The production cross section is found to be $\sigma(e^+ e^-\to f_1) = 0.074 \pm 0.021 \pm 0.010$ 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

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

The cross section of the process $e^+e^- \to \pi^+\pi^-\pi^0\pi^0\eta$ 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 $\omega(782)\pi^0\eta$ final state with a possible small contribution of the $a_0(980)$ resonance in the $\pi^0\eta$ combination. We also observe a presence of the $\rho(770)^{\pm}$ resonance signal in the $\pi^{\pm}\pi^0$ invariant mass distribution.

hep-ex↗

arXiv2026

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

Using more than 600 thousand $K_{S}^{0}\to\pi^{+}\pi^{-}$ decays from the $e^{+}e^{-}\to\phi(1020)\to K_{S}^{0}K_{L}^{0}$ 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 $\phi$-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

Relativistic effects in heavy mesons

We discuss the application of a relativistic potential model to the description of the spectrum and radiative transitions in mesons containing at least one heavy quark (b or c). Although the model has a small number of parameters, it is possible to achieve qualitative agreement with all available experimental data, including those that could not be explained by all previous methods. This demonstrates the importance of taking relativistic effects into account. A remarkable property of the relativistic potential model is that the predictions for meson masses and partial widths of radiative transitions remain finite in the limit of zero light quark mass.

hep-ph↗

arXiv2025

Charge asymmetry in the process $e^+e^-\to \pi^+\pi^-\pi^0\gamma$

The charge asymmetry in the process $e^+e^-\to \pi^+\pi^-\pi^0\gamma$ is studied for photons with energies $\nu\ll\sqrt{s}$. The longitudinal polarization of electrons (positrons) is taken into account. The asymmetry arises due to interference of the amplitudes for production of pion states with opposite $C$ parities. The contribution of $a_1^0(1260)$ meson in the intermediate state to the charge asymmetry is discussed. This contribution is not the leading one, however it is not negligible. It is shown that the charge asymmetry can reach several tens of percent.

hep-ph↗

arXiv2024

Manifestation of $a_1(1260)$ meson in the process $e^+e^-\to π^+π^-π^0$

The charge asymmetry in the process $e^+e^-\to π^+π^-π^0$ is studied taking into account a longitudinal polarization of electrons (positrons). The asymmetry arises due to interference of amplitudes corresponding to production of pions in C-odd and C-even states. It is a manifestation of $a_1(1260)$ meson in the intermediate state. Polarization leads to additional correlations in the differential cross section, which simplifies the experimental study of the process. It is shown that the charge asymmetry can reach several percent.

hep-ph↗

arXiv2024

Measurement of the $e^+e^-\toπ^+π^-$ cross section from threshold to 1.2 GeV with the CMD-3 detector

The cross section of the process $e^+e^-\toπ^+π^-$ has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb$^{-1}$. In the dominant $ρ$-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around $ϕ$-resonance the $π^+π^-$ production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the $π^+π^-$ production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed.

hep-ex↗

arXiv2024

Measurement of the pion form factor with CMD-3 detector and its implication to the hadronic contribution to muon (g-2)

The cross section of the process $e^+e^-\toπ^+π^-$ has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on an integrated luminosity of about 88 pb$^{-1}$, of which 62 pb$^{-1}$ represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the $ρ$ resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed.

hep-ex↗

arXiv2023

Manifestation of the electric dipole moment in the decays of $τ$ leptons produced in $e^+e^-$ annihilation

$\mbox{CP}$-odd asymmetries in the processes $e^+e^-\rightarrow τ^+π^-ν_τ$, $e^+e^-\rightarrow π^+τ^-\barν_ τ$, $e^+e^-\rightarrow τ^+ρ^-ν_τ$, $e^+e^-\rightarrow ρ^+τ^-\barν_τ$, $e^+e^-\to τ^+e^-ν_τ{\barν}_e\,,\,$ and $\,e^+e^-\to τ^-e^+ν_e{\barν}_τ$ are investigated with account for longitudinal polarization of electron (or positron) beam. These asymmetries is a manifestation of electric dipole form factor $F_3^τ\equiv b$ in the $γτ^+τ^-$ vertex. It is shown that, to measure $\mbox{Im}\,b$ in the specified processes, polarization is not needed, while to measure $\mbox{Re}\,b$ it is required. The processes $e^+e^-\to π^+π^-ν_τ{\barν}_τ$, $e^+e^-\to e^+e^-ν_τ{\barν}_τν_e\barν_e$, $e^+e^-\to μ^+μ^-ν_τ{\barν}_τν_μ\barν_μ$, $e^+e^-\to μ^+e^-ν_τ{\barν}_τν_μ\barν_e$, and $e^+e^-\to μ^-e^+ν_τ{\barν}_τν_e\barν_μ$ are also discussed for the case of unpolarized electron and positron beams. In the latter cases it is possible to measure $\mbox{Re}\,b$ using the differential cross section over momenta of both registered particles.

hep-ph↗

arXiv2021

Implementing an expert system to evaluate technical solutions innovativeness

The paper presents a possible solution to the problem of algorithmization for quantifying inno-vativeness indicators of technical products, inventions and technologies. The concepts of technological nov-elty, relevance and implementability as components of product innovation criterion are introduced. Authors propose a model and algorithm to calculate every of these indicators of innovativeness under conditions of incompleteness and inaccuracy, and sometimes inconsistency of the initial information. The paper describes the developed specialized software that is a promising methodological tool for using interval estimations in accordance with the theory of evidence. These estimations are used in the analysis of complex multicomponent systems, aggregations of large volumes of fuzzy and incomplete data of various structures. Composition and structure of a multi-agent expert system are presented. The purpose of such system is to process groups of measurement results and to estimate indicators values of objects innovativeness. The paper defines active elements of the system, their functionality, roles, interaction order, input and output inter-faces, as well as the general software functioning algorithm. It describes implementation of software modules and gives an example of solving a specific problem to determine the level of technical products innovation.

cs.AI↗

arXiv2021

Quadrupole radiation and $e^+e^-$ pair production in the collision of nonrelativistic nuclei

We analyze the one-photon mechanism of $e^+e^-$ pair production in the collision of nonrelativistic nuclei. The contribution of electric quadrupole radiation of virtual photon to the corresponding cross section is found. The effect of the finite nuclear size is considered in detail. A comparison is made with the contribution of electric dipole radiation of virtual photon and with the contribution of the two-photon pair production mechanism. It is shown that the contribution of electric quadrupole radiation is dominant in a wide range of relative velocities. The cross section for the production of $e^+e^-$ pair with the capture of an electron by one of the nuclei is also analyzed.

nucl-th↗