arXiv subjects

E. A. Kravchenko

Publications and source records attributed to E. A. Kravchenko.

At least 19 recordsLinked to original sources

arXiv2026

On peculiarities of the annealing process for highly transparent silica-based aerogel tiles manufactured in Novosibirsk

A collaboration between the Boreskov Institute of Catalysis and the Budker Institute of Nuclear Physics (BINP) has been producing silica aerogel blocks for Cherenkov detectors since 1986. Novosibirsk-manufactured aerogel is used in several experiments: KEDR and SND (BINP, Russia), LHCb (CERN, Switzerland), AMS-02 (ISS), and CLAS12 RICH (Jefferson Lab, USA). This work describes key advancements in the production technology for large-scale aerogel radiators used in Ring-Imaging CHerenkov (RICH) detectors. Annealing is one of the major stages of the highly transparent aerogel production in Novosibirsk. Its procedure was investigated in detail and optimized to improve the yield of aerogel tiles useful for the RICH detectors. The optical and mechanical parameters of the largest silica aerogel samples produced in Novosibirsk using the new annealing procedure are presented.

physics.ins-det↗

arXiv2026

Options for RICH detectors based on silica aerogels for the high-momentum range

Nowadays, several projects of future colliding beam experiments are being considered in the world. Among them are the CEPC (Circular Electron Positron Collider) in China and the FCC (Future Circular Collider) at CERN (Switzerland). To perform experiments on flavor physics in the energy range of the projects an excellent particle identification up to momenta of 30 GeV/c is required. Several concepts of RICH detectors based on aerogel were considered and evaluated with the help of GEANT4 simulation: FARICH (Focusing Aerogel RICH) based on multilayer aerogel with maximal refractive index of 1.008, RICH with Fresnel lens based on aerogel with refractive index of 1.008, RICH based on transparent aerogel fibers with refractive index of 1.008. The results of the simulation are presented. Some results of beam tests at the BINP performed to validate GEANT4 simulation are presented as well.

physics.ins-det↗

arXiv2025

Towards Baikal-Top: Feasibility study of an onshore detector system for the joint registration of EAS with Baikal-GVD

We study the possibility of registering high-energy extensive air showers (EAS) by the onshore detector facility simultaneously with the trigger of the Baikal-GVD neutrino telescope. The location of the surface detector array on the shore of Lake Baikal is motivated by the fact that permanent placement of detectors on the surface of the lake is challenging. Within the given geometry, simultaneous registration is possible for EAS with a zenith angle of about 76 degrees within the limited solid angle. The corresponding inclined EAS are dominated by muons and significantly attenuated. The installation will make it possible to obtain an estimate of the number of high-energy muons in EAS. This, subsequently, would make it possible to verify EAS modeling and calculations of the atmospheric neutrino flux. The detector may also be used for cross-calibration of energy and direction measurements by the neutrino telescope. We use the CORSIKA program to simulate the registration of EAS on the shore close to the Baikal-GVD. The propagation of ultra-high energy muons produced by EAS through 3.5 km of water and their registration by Baikal-GVD is simulated using the PROPOSAL package. We calculate the minimal total area of the onshore detectors suitable for several cosmic ray energy thresholds, starting from 1 PeV. The report presents estimates of the number of events jointly registered by the onshore installation and the Baikal-GVD the EAS registration detector systems with different areas.

astro-ph.IM↗

arXiv2025

The branching fraction measurements of $J/ψ$ decay into $ρη$ and $ϕη$ final states

We present measurements of the branching fractions for the $J/ψ$ meson decays into the $ρη$ and $ϕη$ final states, based on data collected with the KEDR detector at the VEPP-4M collider. The data set consisted of 4.93 million $J/ψ$ events. The resulting branching fractions are: - $\mathcal{B}(J/ψ\to ρη) = (2.04 \pm 0.58 \pm 0.39)\times 10^{-4}$, - $\mathcal{B}(J/ψ\to ϕη) = (7.82 \pm 1.17 \pm 0.58) \times 10^{-4}$, where the first uncertainty is statistical and the second one is systematic. In the study of the $ρη$ decay, the dynamics of $J/ψ\toπ^+π^-η$ is analyzed. The hints from contributions of $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ intermediate states are observed. Additional measured branching fractions in the model that includes $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ are: - $\mathcal{B}(J/ψ\to π^+π^-η) = (4.73 \pm 0.49 \pm 1.17)\times10^{-4}$, - $\mathcal{B}(J/ψ\to (a_2^+π^- + a_2^- π^+)) = (1.05\pm 0.37 \pm 0.34)\times 10^{-3}$, - $\mathcal{B}(J/ψ\to ρ(1450)η\to π^+π^-η) < 1.51 \times 10^{-4}$, at a confidence level of 90\%. All results are consistent with previous studies.

hep-ex↗

arXiv2025

New measurement of D0 and D+ meson masses with the KEDR detector

Using the 4.9 pb$^{-1}$ statistics collected at the peak of the $ψ(3770)$ resonance with the KEDR detector at the VEPP-4M electron-positron collider, we measured the masses of the neutral and charged D mesons: $M_{D^0} = 1865.100 \pm 0.210 (stat) \pm 0.046 (syst) MeV,$ and $M_{D^+} = 1869.560 \pm 0.288 (stat) \pm 0.109 (syst) MeV$.

hep-ex↗

arXiv2024

Four years of wide-field search for nanosecond optical transients with the TAIGA-HiSCORE Cherenkov array

It has been previously demonstrated [Panov et al. Physics of Atomic Nuclei 84(2021)1037] that the TAIGA-HiSCORE Cherenkov array, originally built for cosmic ray physics and ultrahigh-energy gamma-ray astronomy studies using the extensive air shower method, can be used in conventional optical astronomy for wide-field searches for rare nanosecond optical transients of astrophysical origin. The FOV of the facility is on the scale of 1~ster, and it is capable of detecting very rare transients in the visible light range with fluxes greater than approximately 3000~quanta/m$^2$/10~ns (10~ns is the apparatus integration time) and pulse durations of 10\,ns. Among the potential sources of distant nanosecond optical transients are the evaporation of primary black holes, magnetic reconnection in the accretion disks of black holes, and signals from distant lasers of extraterrestrial civilizations. The paper describes the methods and results of the search for optical transients using the TAIGA-HiSCORE Cherenkov array from 2018 to 2022 (four winter seasons of data collection). No reliable astrophysical candidates for optical transients were found. We set an upper bound on the flux of the searched events as $\sim 1\times10^{-3}$\,events/ster/h.

astro-ph.IM↗

arXiv2023

Model-independent extraction of form factors and $|V_{cb}|$ in $\overline{B} \rightarrow D \ell^- \overlineν_\ell$ with hadronic tagging at BaBar

Using the entire BaBar $Υ(4S)$ data set, the first two-dimensional unbinned angular analysis of the semileptonic decay $\overline{B} \rightarrow D \ell^- \overlineν_\ell$ is performed, employing hadronic reconstruction of the tag-side $B$ meson from $Υ(4S)\to B\overline{B}$. Here, $\ell$ denotes the light charged leptons $e$ and $μ$. A novel data-driven signal-background separation procedure with minimal dependence on simulation is developed. This procedure preserves all multi-dimensional correlations present in the data. The expected $\sin^2θ_\ell$ dependence of the differential decay rate in the Standard Model is demonstrated, where $θ_\ell$ is the lepton helicity angle. Including input from the latest lattice QCD calculations and previously available experimental data, the underlying form factors are extracted using both model-independent (BGL) and dependent (CLN) methods. Comparisons with lattice calculations show flavor SU(3) symmetry to be a good approximation in the $B_{(s)}\to D_{(s)}$ sector. Using the BGL results, the CKM matrix element $|V_{cb}|=(41.09\pm 1.16)\times 10^{-3}$ and the Standard Model prediction of the lepton-flavor universality violation variable $\mathcal{R}(D)=0.300\pm 0.004$, are extracted. The value of $|V_{cb}|$ from $\overline{B} \rightarrow D \ell^- \overlineν_\ell$ tends to be higher than that extracted using $\overline{B} \rightarrow D \ell^- \overlineν_\ell$. The Standard Model $\mathcal{R}(D)$ calculation is at a $1.97σ$ tension with the latest HFLAV experimental average.

hep-ex↗

arXiv2023

Measurement of the branching fraction of $J/ψ\rightarrowρπ$ at KEDR

We present the study of the decay $J/ψ\rightarrow ρπ$. The results are based on of 5.2~million $J/ψ$ events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured to be $\B(J/ψ\rightarrow ρπ) = \big(2.072\pm 0.017 \pm 0.062 \big)\cdot 10^{-2}$ and $\B(J/ψ\rightarrow π^+π^-π^0) = \big(1.878 \pm 0.013 \pm 0.051 \big)\cdot 10^{-2}$, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.

hep-ex↗

arXiv2023

Search for $B$ Mesogenesis at BABAR

A new mechanism has been proposed to simultaneously explain the presence of dark matter and the matter-antimatter asymmetry in the universe. This scenario predicts exotic $B$ meson decays into a baryon and a dark sector anti-baryon ($ψ_D$) with branching fractions accessible at $B$ factories. We present a search for $B \rightarrow Λψ_D$ decays using data collected by the $BABAR$ experiment at SLAC. This reaction is identified by fully reconstructing the accompanying $B$ meson and requiring the presence of a single $Λ$ baryon in the remaining particles. No significant signal is observed, and bounds on the $B \rightarrow Λψ_D$ branching fraction are derived in the range $0.13 - 5.2\times 10^{-5}$ for $1.0 < m_{ψ_D} < 4.2$ GeV/$c^{2}$. These results set strong constraints on the parameter space allowed by the theory.

hep-ex↗

arXiv2021

Search for Astrophysical Nanosecond Optical Transients with TAIGA-HiSCORE Array

A wide-angle Cerenkov array TAIGA-HiSCORE (FOV $\sim$0.6 sr), was originally created as a part of TAIGA installation for high-energy gamma-ray astronomy and cosmic ray physics. Array now consist on nearly 100 optical stations on the area of 1 km$^2$. Due to high accuracy and stability ($\sim$1 ns) of time synchronization of the optical stations the accuracy of EAS arrival direction reconstruction is reached 0.1$^\mathrm{o}$. It was proven that the array can also be used to search for nanosecond events of the optical range. The report discusses the method of searching for optical transients using the HiSCORE array and demonstrates its performance on a real example of detecting signals from an artificial Earth satellite. The search for this short flares in the HiSCORE data of the winter season 2018--2019 is carried out. One candidate for double repeater has been detected, but the estimated probability of random simulation of such a transient by background EAS events is not less than 10%, which does not allow us to say that the detected candidate corresponds to a real astrophysical transient. An upper bound on the frequency of optical spikes with flux density of more than $10^{-4} \mathrm{erg/s/cm}^2$ and a duration of more than 5\,ns is established as $\sim 2 \times 10^{-3}$ events/sr/hour.

astro-ph.IM↗

arXiv2020

Measurement of the $e^+e^- \to K^+ K^- π^0$ cross section with the SND detector

The process $e^+e^-\to K^+K^-π^0$ is studied with the SND detector at the VEPP-2000 $e^+e^-$ collider. Basing on data with an integrated luminosity of 26.4~pb$^{-1}$ we measure the $e^+e^-\to K^+K^-π^0$ cross section in the center-of-mass energy range from 1.28 up to 2 GeV. The measured mass spectrum of the $Kπ$ system indicates that the dominant mechanism of this reaction is the transition through the $K^{\ast}(892)K$ intermediate state. The cross section for the $ϕπ^0$ intermediate state is measured separately. The SND results are consistent with previous measurements in the BABAR experiment and have comparable accuracy. We study the effect of the interference between the $ϕπ^0$ and $K^\ast K$ amplitudes. It is found that the interference gives sizable contribution to the measured $e^+e^- \to ϕπ^0\to K^+K^-π^0$ cross section below 1.7 GeV.

hep-ex↗

arXiv2020

Measurements of the Absolute Branching Fractions of $B^\pm \to K^\pm X_{c\bar c}$

A study of the two body decays $B^\pm\rightarrow X_{c\bar c}K^\pm$, where X$_{c\bar c}$ refers to one charmonium state, is reported by BaBar collaboration using a data sample of 424 fb$^{-1}$. The absolute determination of branching fractions for these decays are significantly improved compared to previous BaBaR measurements. Evidence is found for the decay $B^+\rightarrow X(3872)K^+$ at the $3σ$ level. The absolute branching fraction ${\cal B}(B^+\rightarrow X(3872)K^+) = (2.1\pm0.6({\rm stat})\pm0.3({\rm syst}))\times 10^{-4}$ is measured for the first time. It follows that ${\cal B}(X(3872)\rightarrow J/ψπ^+π^-)=(4.1\pm1.3)\%$, supporting the hypothesis of a molecular component for this resonance.

hep-ex↗

arXiv2020

Precision measurement of the ${\cal B}(Υ(3S)\toτ^+τ^-)/{\cal B}(Υ(3S)\toμ^+μ^-)$ ratio

We report on a precision measurement of the ratio ${\cal R}_{τμ}^{Υ(3S)} = {\cal B}(Υ(3S)\toτ^+τ^-)/{\cal B}(Υ(3S)\toμ^+μ^-)$ using data collected with the BaBar detector at the SLAC PEP-II $e^+e^-$ collider. The measurement is based on a 28 fb$^{-1}$ data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million $Υ(3S)$ mesons. The ratio is measured to be ${\cal R}_{τμ}^{Υ(3S)} = 0.966 \pm 0.008_\mathrm{stat} \pm 0.014_\mathrm{syst}$ and is in agreement with the Standard Model prediction of 0.9948 within 2 standard deviations. The uncertainty in ${\cal R}_{τμ}^{Υ(3S)}$ is almost an order of magnitude smaller than the only previous measurement.

hep-ex↗

arXiv2020

Search for lepton-flavor violating decays $D^{0}\rightarrow X^{0}e^{\pm}μ^{\mp}$

We present a search for seven lepton-flavor-violating neutral charm decays of the type $D^{0}\rightarrow X^{0} e^{\pm} μ^{\mp}$, where $X^{0}$ represents a $π^{0}$, $K^{0}_{\rm S}$, $\bar{K^{*0}}$, $ρ^{0}$, $ϕ$, $ω$, or $η$ meson. The analysis is based on $468$ fb$^{-1}$ of $e^+e^-$ annihilation data collected at or close to the $Υ(4S)$ resonance with the BaBar detector at the SLAC National Accelerator Laboratory. No significant signals are observed, and we establish 90\% confidence level upper limits on the branching fractions in the range $(5.0 - 22.5)\times 10^{-7}$. The limits are between one and two orders of magnitude more stringent than previous measurements.

hep-ex↗

arXiv2020

Search for rare or forbidden decays of the $D^{0}$ meson

We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type $D^0\rightarrow h^{\prime -} h^{-}\ell^{\prime +} \ell^{+}$ and $D^0\rightarrow h^{\prime -} h^{+}\ell^{\prime\pm} \ell^{\mp}$, where $h$ and $h^{\prime}$ represent a $K$ or $π$ meson and $\ell$ and $\ell^{\prime}$ an electron or muon. The analysis is based on $468$ fb$^{-1}$ of $e^+e^-$ annihilation data collected at or close to the $Y(4S)$ resonance with the BaBar detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes and we establish 90% confidence level upper limits on the branching fractions in the range $(1.0 - 30.6)\times 10^{-7}$. The limits are between one and three orders of magnitude times more stringent than previous measurements.

hep-ex↗

arXiv2019

Search for $B^- \to Λ\bar p ν\barν$ with the BABAR experiment

We search for the rare flavor-changing neutral current process $B^- \to Λ{\overline p} ν{\overlineν}$ using data from the BABAR experiment. A total of 424 fb$^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy of the $Υ$(4S) resonance is used in this study, corresponding to a sample of ${(471 \pm 3) \times 10^{6}}$ $B\overline{B}$ pairs. Signal $B^- \to Λ{\overline p} ν{\overlineν}$ candidates are identified by first fully reconstructing a $B^+$ decay in one of many possible exclusive decays to hadronic final states, then examining detector activity that is not associated with this reconstructed $B^+$ decay for evidence of a signal $B^- \to Λ{\overline p} ν{\overlineν}$ decay. The data yield is found to be consistent with the expected background contribution under a null signal hypothesis, resulting in an upper limit of ${{\cal B} (B^- \to Λ{\overline p} ν{\overlineν}) < 3.0\times 10^{-5}}$ at the $90\%$ confidence level.

hep-ex↗

arXiv2018

Precise measurement of $R_{\text{uds}}$ and $R$ between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.

hep-ex↗

arXiv2018

Measurement of $Γ_{ee}\times\mathcal{B}_{μμ}$ for $ψ(2S)$ meson

The product of the electronic width of the $ψ(2S)$ meson and the branching fraction of its decay to the muon pair was measured in the $e^{+}e^{-} \to ψ(2S) \to μ^{+}μ^{-}$ process using nine data sets corresponding to an integrated luminosity of about 6.5 pb$^{-1}$ collected with the KEDR detector at the VEPP-4M electron-positron collider: \[ Γ_{ee}\times\mathcal{B}_{μμ} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}. \] Adding the previous KEDR results on hadronic and leptonic channels, the values of the $ψ(2S)$ electronic width were obtained under two assumptions: either with the assumption of lepton universality \[ Γ_{ee} = 2.279 \pm 0.015 \pm 0.042 ~\text{keV} \] or without it, summing up hadronic and three independent leptonic channels: \[ Γ_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}. \]

hep-ex↗