The cross section of the process e+e- -> x-+x-- 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 p-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around 0-resonance the x-+x-- production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the x-+x-- 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.

The review discusses the physical program of a new experiment at the Super Charm-Tau factory, the basis of which will be a powerful electron-positron collider with a luminosity of- 1035 cm(-2) s(-1) and an energy in the center of mass system in the range from 3 to 5 GeV. A modern detector located around the beam collision point will provide a new level of measurement accuracy. The longitudinal polarization of the electron beam, along with record luminosity, will allow the unique experiment to successfully compete with the existing Super B-factories Belle II and LHCb. The extensive physical program includes the study of the properties and measurement of physical parameters of charmed hadrons, the tau-lepton, the charmonium, and exotic states, as well as the study of the production of light hadrons in e(+)e(-)-annihilation and in two-photon processes. In addition to testing the Standard Model and precisely measuring its parameters, a comprehensive search for New Physics beyond its boundaries is planned.

The cross section of the process $e^+e^-\to\pi^+\pi^-$ 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 $\rho$ 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.

The conversion decay w® p0e+e- with the CMD-3 detector on the VEPP-2000 electron-positron collider VEPP-2000 at the Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences was investigated. The data from the first scan were used in the work, which corresponded to an integral brightness of around 10 pb–1 in the energy range of 660 to 840 MeV in the center of mass system. The 1113 ± 37 signal events were detected. The product of the relative decay probability and ω-meson width G(w® e+e- ) × Br(w® p0e+e- ) = (4, 20 ± 0,12 ± 0, 25) ×10-7 MeV, as well branching ratio Br(w® p0e+e- ) = (6, 78 ± 0,19 ± 0, 40) ×10-4 are measured with better precision than the world average.

The experiment on photodisintegration of tensor polarized deuteron is in progress. It is carried out at VEPP-3 storage ring using the internal polarized gas target technique. The component T20 of the tensor analyzing power is obtained by measuring the target polarization asymmetry in the photon energy range up to 1600MeV. The energy of photons is defined by the system that tags nearly real photons developed at the Budker Institute of Nuclear Physics (BINP).

New results for the T20-component of the tensor-analyzing power of the incoherent negative pion photoproduction are presented. The experiment was performed for the electron beam energy of 800 MeV at the VEPP-3 storage ring in 2021. To extract the T20-component, we used asymmetry with respect to the change in the sign of the tensor polarization of the deuteron target. Identification of the reaction events was carried out by the detection of two protons in coincidence. Experimental data were compared with the results of statistical simulation, considering the interaction between the NN and πN subsystems in the final state of the reaction.

The super τ-charm facility (STCF) is an electron–positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 × 1035 cm−2·s−1 or higher. The STCF will produce a data sample about a factor of 100 larger than that of the present τ-charm factory — the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R D and physics case studies.

We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω[over ˜]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ω[over ˜]_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.

A cross section of the process e+e−→KS0K±π∓π+π− has been measured for the first time using a data sample of 185.4 pb−1 collected with the CMD-3 detector at the VEPP-2000 e+e− collider. With the KS0→π+π− decay detection, 373±20 and 514±28 signal events have been selected with six and five reconstructed tracks, respectively, in the center-of-mass energy range 1.6–2.0 GeV. The total systematic uncertainty of the cross section is about 15%. A study of the production dynamics allows us to extract a contribution from the e+e−→f1(1285)π+π− intermediate state and to measure the corresponding cross section. The intermediate states with the f1(1420) and f1(1510) resonances have been observed.

The Mu2e experiment at Fermilab will search for the neutrinoless μ−→e− conversion in the field of an aluminum nucleus. The Mu2e data-taking plan assumes two running periods, Run I and Run II, separated by an approximately two-year-long shutdown. This paper presents an estimate of the expected Mu2e Run I search sensitivity and includes a detailed discussion of the background sources, uncertainties of their prediction, analysis procedures, and the optimization of the experimental sensitivity. The expected Run I 5σ discovery sensitivity is Rμe=1.2×10−15, with a total expected background of 0.11±0.03 events. In the absence of a signal, the expected upper limit is Rμe<6.2×10−16 at 90% CL. This represents a three order of magnitude improvement over the current experimental limit of Rμe<7×10−13 at 90% CL set by the SINDRUM II experiment.

The cross section of the process $e^+e^-\to\pi^+\pi^-$ 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 $\rho$-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around $\phi$-resonance the $\pi^+\pi^-$ production cross section was measured for the first time with high energy resolution. The forward-backward charge asymmetry in the $\pi^+\pi^-$ production has also been measured. It shows the strong deviation from the theoretical prediction based on conventional sQED framework and is in good agreement with GVDM and dispersive-based predictions. The impact of presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed.

This paper describes the design of a simulation model of the infrastructure for data processing fromthe Super Charm-Tau factory class "megasience" electron-positron collider. The model simulates thebehavior of the main subsystems of a supercomputer, such as the task scheduler, computing clusters,data storage system, etc. Using simulation modeling allows for the maximally reliable representationof the exact characteristics and volume of the needed equipment for developing the desired HPCsystem. The simulation model accounts for all the aspects of operation of this system from paralleldata storage system to arrangement of the parallel launch of tasks. The developed system forprocessing software errors and equipment failures, as well as the system for ensuring energy efficiencymake it possible to estimate the needed equipment with account for all possible emergency situations.This model allows calculating the parameters of the computing system necessary for processing andstoring the results of operation of the Super Charm-Tau factory after its commissioning.

We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ω[over ˜]_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ω[over ˜]_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.

This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muon g - 2 Experiment. Two corrections to the measured muon precession frequency omega(m)(a) are associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary, because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designed RC time constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections to omega(m)(a) is 0.50 +/- 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of omega(m)(a).

The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 in December 2010 with a goal to collect about 1 fb −1 . The collected data sample corresponds to an integrated luminosity of 200 pb −1 in the center-of-mass energy range from 0.32 up to 2 GeV. This paper reports recent results on the hadronic cross sections measurements with the CMD-3 detector.

The cross section of the process e+e−→KS0KS0π+π− has been measured using a data sample of 56.7 pb−1 collected with the CMD-3 detector at the VEPP-2000 e+e− collider. 596±27 and 210±18 signal events have been selected with six and five detected tracks, respectively, in the center-of-mass energy range 1.6–2.0 GeV. The total systematic uncertainty of the cross section is about 10%. The study of the production dynamics confirms the dominance of the K⁎(892)+K⁎(892)− intermediate state.

A recent result of the cross section measurement of the process e(+)e(-) -> KSK +/-pi(-/+) e(+)e(-) collider VEPP-2000 is presented using a data sample of the similar to 150 pb(-1) integrated luminosity collected with the CMD-3 detector. The processes with charged kaons in multi hadron events attract special interest, because they impact strongly on studies of light quark hadronization, isospin symmetry, and strange meson spectroscopy. Experimental results of e(+)e(-) -> KSK +/-pi(-/+) cross section are presented in a broad energy range covered by the VEPP-2000 and compared to earlier measurements. A study of the production dynamics confirms the dominance of neutral KK*(892) intermediate state.

This paper reports a current status of the measurements of the hadronic cross sections in the c.m. energy range from 0.32 to 2.0 GeV with the CMD-3 detector at the VEPP-2000 electron-positron collider. The overall size of the data, acquired by the CMD-3 in the runs of 2010–2013 and 2017–2018 years, is about 160 pb−1. The results of data analysis for various exclusive modes of e+e−→hadrons are described.

E.A.Kozyrev1,2, E.P.Solodov1,2, R.R.Akhmetshin1, A.N.Amirkhanov1,2, A.V.Anisenkov1,2, V.M.Aulchenko1,2, V.S.Banzarov1, N.S.Bashtovoy1, D.E.Berkaev1,2, A.E.Bondar1,2, A.V.Bragin1, S.I.Eidelman1,2, D.A.Epifanov1,2, L.B.Epshteyn1,2,3, A.L.Erofeev1,2, G.V.Fedotovich1,2, S.E.Gayazov1,2, A.A.Grebenuk1,2, S.S.Gribanov1,2, D.N.Grigoriev1,2,3, F.V.Ignatov1, V.L.Ivanov1,2, S.V.Karpov1, A.S.Kasaev1, V.F.Kazanin1,2, A.A.Korobov1,2, I.A.Koop 1, A.N.Kozyrev1,2, P.P.Krokovny1,2, A.E.Kuzmenko1,2, A.S.Kuzmin1,2, I.B.Logashenko1,2, P.A.Lukin1,2, A.P.Lysenko1, K.Yu.Mikhailov1,2, V.S.Okhapkin1, E.A.Perevedentsev1,2, Yu.N.Pestov1, A.S.Popov1,2, G.P.Razuvaev1,2, Yu.A.Rogovsky1,2, A.A.Ruban1, N.M.Ryskulov1, A.E.Ryzhenenkov1,2, V.E.Shebalin1,2, D.N.Shemyakin1,2, B.A.Shwartz1,2, D.B.Shwartz1,2, A.L.Sibidanov4, Yu.M.Shatunov1, A.A.Talyshev1,2, A.I.Vorobiov1, Yu.V.Yudin1,2