It has been previously demonstrated by Panov et al. (2021) 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 field of view 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/m2/10 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 ∼ 1pt 1 ×10^ - 3 events/ster/h.

The Super Charm-Tau Factory project is a future electron-positron colliding beam experiment with unprecedented high luminosity of 1035cm-2s-1 at the center of mass energy range from 3 to 7GeV. To perform the broad physics program, the high-performance universal detector is proposed. One of the main detector subsystems is the FARICH (Focusing Aerogel RICH) detector. The proposed FARICH scheme combined with abilities of tracking system will provide the excellent pi/K-separation for the whole operation momentum range and mu/pi-separation up to momentum of 1.5GeV/c. In 2023 two multilayer focusing aerogel samples with record overall sizes 230x230x35mm were produced in Novosibirsk. The results of the beam tests of these aerogel samples and comparison with simulation are presented. Conceptual design and some technical issues of the dedicated particle identification system based on FARICH technique are discussed as well.

Using the entire BABAR gamma(4S) dataset, the first two-dimensional unbinned angular analysis of the semileptonic decay (B) over bar -> Dl(-)(v) over bar (l) is performed, employing hadronic reconstruction of the tag-side B meson from gamma(4S) -> B (B) over bar. Here, l denotes the light charged leptons e and mu. Anovel data-driven signal-background separation procedure with minimal dependence on simulation is developed. This procedure preserves all multidimensional correlations present in the data. The expected sin(2) theta(l) dependence of the differential decay rate in the Standard Model is demonstrated, where theta(l) 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) -> D-(s) sector. Using the BGL results, the CKM matrix element vertical bar V-cb vertical bar = (41.09 +/- 1.16) x 10(-3) and the Standard Model prediction of the lepton-flavor universality violation variable R(D) = 0.300 +/- 0.004, are extracted. The value of vertical bar V-cb vertical bar from (B) over bar -> Dl(-)(v) over bar (l) tends to be higher than that extracted using (B) over bar -> Dl(-)(v) over bar (l). The Standard Model R(D) calculation is at a 1.97 sigma tension with the latest HFLAV experimental average.

The ASHIPH (Aerogel, SHifter, PHotomultiplier) Cherenkov counters are considered as a particle identification system alternative option for the detector on future Super Charm-Tau factory. The ASHIPH counters have been operating successfully in the KEDR and SND experiments in Novosibirsk at the Budker Institute of Nuclear Physics. Previously in our experiments Micro Channel Plate PMTs were used for the photon detection in the ASHIPH counters. Now, we have developed a prototype of the ASHIPH counter with SiPM (Silicon PMTs) array as a photodetector. Such an upgrade will increase the number of detected photoelectrons by 2.5 times and consequently improve the quality of particle separation. The results of testing the ASHIPH counter prototype on the electron test beam facility of the VEPP-4M accelerator is presented.

The paper is devoted to the modeling and analysis of data detected by the TAIGA-IACT installation in the stereo mode. Five Imaging Atmospheric Cherenkov Telescopes (IACT) with a viewing angle of 9.6° are expected to be included in the installation. Today there are three telescopes spaced far apart (from 320 to 500 m) in the installation. The effective area of the installation is as large as 0.6 km2; therefore, it is possible to conduct statistically significant measurements of weak γ-ray sources in the energy range above 10 TeV over a reasonable observation time (300–400 h). The Monte Carlo procedure for simulating the hadrons and γ-rays detected by the telescopes is described as is the procedure for reconstructing the parameters of extensive air showers, such as the arrival direction of an event, the axis position, the depth of the maximum of shower development (Xmax), and the primary-particle energy. In order to solve the problem of γ-hadron separation, the criteria for selecting γ-rays detected in the stereo mode have been optimized and the effective area of the installation has been calculated.

— The review presents the experiments performed with the KEDR detector at the e^ + e^ - collider VEPP-4M in the energy range of √(s) = 1.84–3.88 GeV. The cross section of e^ + e^ - annihilation to hadrons was measured at 22 points of this range and the search for narrow resonances was conducted below 3.1 GeV. The masses of J / . -0emψ and ψ (2S) mesons were measured with a record accuracy better than 3 ×10^ - 6 ; their partial and total widths were determined. Measurements of the tau lepton mass and masses of charged and neutral D mesons were performed with high precision. The measurements of the ψ (3770) parameters are discussed, and attention is drawn to some inconsistency of the procedure employed by the Particle Data Group for determining its parameters.

We study the processes e+e- -> K+K-a degrees a degrees a degrees y, K degrees SK +/- a -/+ a degrees a degrees y, and K degrees SK +/- a -/+ a+a-y in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at the SLAC National Accelerator Laboratory. About 1200, 2600, and 6000 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb-1. The invariant mass of the hadronic final state defines the effective e+e- center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e+e- -> K+K-a degrees a degrees a degrees, e+e- -> K degrees SK +/- a -/+ a degrees a degrees, and e+e- -> K degrees SK +/- a -/+ a+a- cross sections are performed. The contributions from the intermediate states that include eta, phi, rho, K*(892), and other resonances are presented. We observe the J=psi and psi(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.

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 ($\psi_D$) with branching fractions accessible at $B$ factories. We present a search for $B \rightarrow \Lambda \psi_D$ 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 $\Lambda$ baryon in the remaining particles. No significant signal is observed, and bounds on the $B \rightarrow \Lambda \psi_D$ branching fraction are derived in the range $0.13 - 5.2\times 10^{-5}$ for $1.0 < m_{\psi_D} < 4.2$ GeV/$c^{2}$. These results set strong constraints on the parameter space allowed by the theory.

We study the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$, ${K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$, and ${K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at the SLAC National Accelerator Laboratory. About 1200, 2600, and 6000 events, respectively, are selected from a data sample corresponding to an integrated luminosity of $469\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The invariant mass of the hadronic final state defines the effective ${e}^{+}{e}^{\ensuremath{-}}$ center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$, and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ cross sections are performed. The contributions from the intermediate states that include $\ensuremath{\eta}$, $\ensuremath{\phi}$, $\ensuremath{\rho}$, ${K}^{*}(892)$, and other resonances are presented. We observe the $J/\ensuremath{\psi}$ and $\ensuremath{\psi}(2S)$ in most of these final states and measure the corresponding branching fractions, many of them for the first time.

The more correct recalculation from the measured Cherenkov light fluxes at distances of 200 (Q200) and 100 (Q100) m from the Extensive Air Shower (EAS) core to the energy of the primary particle has been developed using the results of M-C simulation by the CORSIKA code, assuming a light primary composition of cosmic rays. Using the new conversion expressions, a differential energy spectrum was obtained according to the data of the Tunka-133 array for 7 years of operation and the TAIGA-HiSCORE array for 2 years of operation.

A dedicated measurement of additional radiation in e+e- -> mu+mu- gamma and e+e- -> pi+ pi- gamma initial-state radiation events is presented using the full BABAR data sample. For the first time results are presented at next -to-and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. Comparison with predictions from PHOKHARA and AFKQED Monte Carlo generators is performed, revealing discrepancies in the one-photon rates and angular distributions for the former. This disagreement has a negligible effect on the BABAR measurement of the e+e- -> pi+ pi-(gamma) cross section, but could affect other measurements significantly. This study sheds a new light on the longstanding discrepancy in this channel that affects the theoretical prediction of hadronic vacuum polarization contributions to the muon magnetic moment anomaly.

The concept of the TAIGA experiment is to combine wide-angle timing and imaging Cherenkov telescopes as well as electron and muon detectors. The TAIGA facility aims at gamma-ray astrophysics at energies from a few TeV to several PeV and cosmic-ray physics from 100 TeV to several EeV but also pursues searches for astrophysical nanosecond transients, axion-like particles, Lorentz invariance violation and other unexpected manifestations of New Physics. TAIGA-1, a hybrid detector complex with an area of 1 km2, operating since 2021 in the Tunka valley, 50 km to the West from the southernmost tip of lake Baikal, and the plans for its upgrade are presented.

A new dark sector antibaryon, denoted ψ_{D}, could be produced in decays of B mesons. This Letter presents a search for B^{+}→ψ_{D}+p (and the charge conjugate) decays in e^{+}e^{-} annihilations at 10.58 GeV, using data collected in the BABAR experiment. Data corresponding to an integrated luminosity of 398  fb^{-1} are analyzed. No evidence for a signal is observed. Branching fraction upper limits in the range from 10^{-7}-10^{-5} are obtained at 90% confidence level for masses of 1.0<m_{ψ_{D}}<4.3  GeV/c^{2}. The result is also reinterpreted to provide the first limits on a supersymmetric model with R-parity violation and a light neutralino.

The Tunka Advanced Instrument for Gamma-ray and cosmic ray Astrophysics (TAIGA) is a hybrid experiment for the measurement of Extensive Air Showers (EAS) with good spectral resolution in the TeV to PeV energy range. In this domain, the long-sought Pevatrons can be detected. Currently the hybrid TAIGA detector combines two wide angle shower front Cherenkov light sampling timing arrays (HiSCORE and Tunka-133), two 4m class, 10 degrees aperture Imaging Air Cherenkov Telescopes (IACTs) and 240 m(2) surface and underground charged particle detector stations. Our goal is to introduce a new hybrid reconstruction technique, combining the good angular and shower core resolution of HiSCORE with the gamma-hadron separation power of imaging telescopes. This approach allows to maximize the effective area and simultaneously to reach a good gamma-hadron separation at low energies (few TeV). At higher energies, muon detectors are planned to enhance gamma-hadron separation. During the commissioning phase of the first and second IACT, several sources were observed. First detections of known sources with the first telescope show the functionality of the TAIGA IACTs. Here, the status of the TAIGA experiment will be presented, along with first results from the current configuration.

An analysis is performed of the spectrum of gamma rays from the Crab Nebula in the 4–100 TeV range of energies, obtained using data from two Atmospheric Cherenkov Telescopes that are part of the TAIGA complex. A way of selecting and restoring the energy of gamma rays is described that includes a procedure for restoring the energy spectrum.

The Tunka-Grande scintillation array is described. Scientific results obtained over the first five years of its operation are presented. Prospects for studying cosmic rays in the 1016–1018 eV range of energies are discussed.

A dedicated measurement of additional radiation in $e^+e^-\to\mu^+\mu^-\gamma$ and $e^+e^-\to\pi^+\pi^-\gamma$ initial-state-radiation events is presented using the full BABAR data sample. For the first time results are presented at next-to- and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. Comparison with predictions from Phokhara and AfkQed Monte Carlo generators is performed, revealing discrepancies in the one-photon rates and angular distributions for the former. This disagreement has a negligible effect on the BABAR measurement of the $e^+e^-\to\pi^+\pi^-(\gamma)$ cross section, but could affect other measurements significantly. This study sheds a new light on the longstanding discrepancy in this channel that affects the theoretical prediction of hadronic vacuum polarization contributions to the muon magnetic moment anomaly.

We present a new technique, "tau polarimetry," for measuring the longitudinal beam polarization present in an e(+)e(-) collider through the analysis of e(+)e(-) -> tau(+)tau(-) events. By exploiting the sensitivity of tau decay kinematics to the longitudinal polarization of the beams, we demonstrate that the longitudinal polarization can be measured with a 3 per mil systematic uncertainty at the interaction point using a technique that is independent of spin and beam transport modeling. Using 424.2 +/- 1.8 fb(-1) of BABAR data at root s = 10.58 GeV, the average longitudinal polarization of the PEP-II e(+)e(-) collider has been measured to be < P > = 0.0035 +/- 0.0024(stat) +/- 0.0029(sys). The systematic uncertainty studies are described in detail, which can serve as a guide for future applications of tau polarimetry. A proposed e(-) beam longitudinal polarization upgrade to the SuperKEKB e(+)e(-) collider would benefit from this technique.

We present a new technique, ``tau polarimetry,'' for measuring the longitudinal beam polarization present in an ${e}^{+}{e}^{\ensuremath{-}}$ collider through the analysis of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ events. By exploiting the sensitivity of $\ensuremath{\tau}$ decay kinematics to the longitudinal polarization of the beams, we demonstrate that the longitudinal polarization can be measured with a 3 per mil systematic uncertainty at the interaction point using a technique that is independent of spin and beam transport modeling. Using $424.2\ifmmode\pm\else\textpm\fi{}1.8\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of BABAR data at $\sqrt{s}=10.58\text{ }\text{ }\mathrm{GeV}$, the average longitudinal polarization of the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ collider has been measured to be $⟨P⟩=0.0035\ifmmode\pm\else\textpm\fi{}0.002{4}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}0.002{9}_{\mathrm{sys}}$. The systematic uncertainty studies are described in detail, which can serve as a guide for future applications of tau polarimetry. A proposed ${e}^{\ensuremath{-}}$ beam longitudinal polarization upgrade to the SuperKEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider would benefit from this technique.