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 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 measurement of the cross-section of the processp(+)p???????(-)p(???????0) ??????? with the CMD-3 detector at the electron-positron collider VEPP-2000 in the energy region below 1 GeV in c.m.s. based on a part of the collected statistics with an integrated luminosity of about 16.35 pb(-1) is presented. The measured cross-section has been analyzed in the framework of the vector meson dominance model taking into account the interference of ?, ?, f, ?' , ?" resonances. PACS numbers: 12.40.Vv

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.

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 cross section of the process e+ e– → π+ π– π0 was measured with the CMD-3 detector at the electron-positron collider VEPP-2000 in the ω meson energy region based on the data collected in 2013–2018 and corresponding to an integrated luminosity of 40 pb–1. The parameters of the ω-meson: Mω = 782.67 ± 0.01 ± 0.1 MeV, Γω = 8.56 ± 0.02 ± 0.07 MeV, σ0(ω → π+ π– π) = 1629 ± 3 ± 36 nb with the precision match or even exceeding the previous data are obtained.

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

The cross section of the process e+ e– → π+ π– π0 was measured with the CMD-3 detector at the electron-positron collider VEPP-2000 in the energy region from 750 MeV to 800 MeV in c.m.s. This measurement was based on the data collected in 2013 and related to an integrated luminosity of about 7.8 pb–1. The procedure for obtaining the Born cross section and determining the parameters of the ω-meson was worked out. The preliminary ω-meson parameters mω = 782.70 ± 0.02 ± ± 0.11 MeV, Гω = 8.74 ± 0.05 ± 0.22 MeV, σ0(ω → π+ π– π) = 1545 ± 4 ± 39 nb were obtained. The results were compared with previous data and proven to demonstrate a good agreement with them.

Precise study of the hadrons production in \bm{e^+e^-}𝐞+𝐞− annihilation at low energies provides important information about interactions of light quarks and spectroscopy of their bound states. These studies are especially important for theoretical calculations of the muon \bm{(g-2)}(𝐠−2) via the Standard Model because of the present difference between theoretical and experimental values exceeds three standard deviations. In this report we will discuss current status and recent results obtained by the CMD-3 experiment and will give a brief look to status of the BaBar and Belle II experiments.

The process e+e−→K+K−η has been studied in the center-of-mass energy range from 1.59 to 2.007 GeV using the data sample of 59.5 pb−1, collected with the CMD-3 detector at the VEPP-2000 e+e− collider in 2011, 2012 and 2017. The K+K−η final state is found to be dominated by the contribution of the ϕ(1020)η intermediate state. The cross section of the process e+e−→ϕ(1020)η has been measured with a systematic uncertainty of 5.1% on the base of 3009 ± 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: aμϕη(E<1.8GeV)=(0.321±0.015stat±0.016syst)×10−10, aμϕη(E<2.0GeV)=(0.440±0.015stat±0.022syst)×10−10. From the cross section approximation the ϕ(1680) meson parameters have been determined with better statistical precision, than in previous studies.

Regular data taking with the CMD-3 at the electron-positron collider VEPP-2000 is under way since 2010. The collected data sample corresponds to about 200 inverse picobarns of integrated luminosity per detector in the energy range from 0.32 up to 2 GeV, with a goal to collect about 1 fb−1 during next five years. Some of the recent results from the CMD-3 detector are discussed.

The CMD-3 detector is installed at the VEPP-2000 e+e− collider at BINP (Novosibirsk, Russia). It is a general-purpose detector, equipped with a tracking system, two crystal (CSI and BGO) calorimeters, liquid Xe calorimeter, TOF and muon systems. The main goal of experiments at CMD-3 is a study of exclusive modes of e+e−→ hadrons at energies $ \sqrt s \le $ GeV. In particular, these results provide an important input for calculation of the hadronic contribution to the muon anomalous magnetic moment. The first round of data taking was performed in 2011–2013, when about 60 1/pb were taken in the center-of-mass (c.m.) energy range from 0.32 to 2.0 GeV. Here we present a survey of results of data analysis. Between 2013 and 2016 the collider and the detector were upgraded. The data taking resumed by the end of 2016. In the first run after the upgrade about 50 1/pb were collected at the energy range between 1.28 and 2.007 GeV. We discuss the upgrade and the first preliminary results from the new data.

A large amount of data collected with the CMD-3 detector above the threshold of the nn̅pair allows to measure the cross section of the process e+e−→ nn̅and the neutron form factor with good accuracy. This task is complicated by a large number of background events and necessity of finding ways to suppress them. A technique of identification for e+e−→ nn̅events is described.

The cross section of the process e+ e−→ KS KL π0 has been studied with the CMD-3 detector at the VEPP-2000 electron-positron collider in the center-of-mass energy range from 1.1 to 2 GeV. Preliminary results on the total cross section of the process are presented.