Study of the process e+e−→3(π+π−) in the c.m. energy range 1.5–2.0 GeV with the CMD-3 detector

AbstractThe cross section of the process e+e−→3(π+π−) has been measured using a data sample of 22 pb−1 collected with the CMD-3 detector at the VEPP-2000 e+e− collider. 7956 signal events are selected in the center-of-mass energy range 1.5–2.0 GeV. The measured cross section exhibits a sharp drop near the pp¯ threshold. A first study of dynamics of six-pion production has been performed

Study of the process e+e− → 2(π+π−π0) with the CMD-3 detector at VEPP-2000 collider

Since 2010 the CMD-3 detector has been collecting data at the VEPP-2000 e+e− collider. CMD-3 is a general purpose detector designed to study e+e− annihilation into hadrons in the center-of-mass (c.m.) energy range from 0.3 up to 2 GeV. Preliminary results for the e+e− → 2(π+π−π0) cross section were obtained in the c.m. energy range from 1.5 up to 2 GeV. The analysis is based on a data sample of 22 pb−1

Study of the process e+e−→π+π−π+π− in the c.m. energy range 920–1060 MeV with the CMD-3 detector

A cross section of the process e+e−→π+π−π+π− has been measured using 6798±93 signal events from a data sample corresponding to an integrated luminosity of 9.8 pb−1 collected with the CMD-3 detector in the center-of-mass energy range 920–1060 MeV. The measured cross section exhibits a pattern of interference of the ϕ(1020)→π+π−π+π− decay with a non-resonant process e+e−→π+π−π+π−, from which we obtain the branching fraction of the doubly suppressed decays (by G-parity and OZI rule): B(ϕ→π+π−π+π−)=(6.5±2.7±1.6)×10−6

Search for the process e+e−→η′(958) with the CMD-3 detector

A search for the process e+e−→η′(958) in the π+π−η→π+π−γγ final state has been performed with the CMD-3 detector at the VEPP-2000 e+e− collider. Using an integrated luminosity of 2.69 pb−1 collected at the center-of-mass energy Ec.m.=957.68 MeV we set an upper limit for the product of electronic width and branching fractions Γη′(958)→e+e−⋅Bη′(958)→π+π−η⋅Bη→γγ<0.00041 eV at 90% C.L

Study of the processes

The data sample collected in 2011-2013 at the c.m.s. energies between 0.32-2 GeV with the CMD-3 detector operating at the VEPP-2000 e+e− collider is analzed. The collected data corresponds to an integrated luminosity about ∼ 60pb−1. The techniques for determination of the integrated luminosity for each energy setting is described. Some preliminary results of the study of the processes e+e−→ K+ K− + nπ (n = 1,2,3) with two charged kaons in the final state are presented. These processes have several intermediate states, which are important to correctly descript the angular distributions of final particles and the cross sections dependence on the energy

CMD-3 Overview

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