Abstract
Since December 2010 the CMD-3 and SND detectors detectors collect data at the VEPP-2000 electron-positron collider. In 2013-2015 the injection facility of the collider has undergone an upgrade of the injection system. The new BINP injection complex has been connected to the VEPP-2000 collider, so the restrictions connected to the lack of positrons and limited beam energy transfer do not apply any more. The collider luminosity in whole energy range is restricted now only by beam-beam effects. VEPP-2000 collider started to collect data with two detectors at 2016 year. The collected data sample since 2010 corresponds more than 100 pb-1 of integrated luminosity per detector in the c.m. energy between 0.32 and 2GeV. We will report here results of analysis of various hadronic cross sections from detectors both published and preliminary. These measurements are important by themselves and also because of the implications for anomaly of the magnetic moment of a muon (g-2) discrepancy.
Highlights
Presented are the results of the analysis of data collected on the CMD-3 and the Spherical Neutral Detector (SND) detectors installed in the interaction regions of the VEPP-2000 collider [1]
The Cryogenic Magnetic Detector (CMD-3) [2] (Fig.1) includes a tracking system consisting of a cylindrical drift chamber (DC) and a double-layer cylindrical multiwire proportional chamber (Zchamber) installed inside a thin superconducting solenoid with a 1.3 T field
The e+e− → π0γ has the third largest cross section in the c.m. energy region below 1 GeV, related with φ, ω and ρ mesons radiative decays and the transition formfactor π0γ∗γ. This cross section has been measured with SND detector [10] (Fig.4) using the full statistics collected at VEPP-2000 and previous VEPP-2M colliders
Summary
Presented are the results of the analysis of data collected on the CMD-3 and the SND detectors installed in the interaction regions of the VEPP-2000 collider [1]. Collider can operate in c.m. energies 0.3 − 2.0 GeV. The Spherical Neutral Detector (SND) (Fig.2)[4, 5] includes a spherical electromagnetic calorimeter, a cylindrical tracking system, a threshold Cherenkov counters and a cosmic events veto detector. Electromagnetic calorimeter covers 0.95 × 4π of the solid angle, has 13.4 X0 thickness, its energy resolution δE E. (2) Hadron spectroscopy: study of light-vector-meson exitations, in particular, search for their radiative decays. (7) Using radiative return technique as alternative method for measurement of hadronic cross sections. (8) Measurement of exclusive hadronic cross sections below 2 GeV. Total statistics recorded for both detectors during 2010-2013 run is about 135 pb−1, where ∼ 17 pb−1 are recorder in the ∼ ω-region, ∼ 19 pb−1 for energies below 1 GeV ( except ω-region), ∼ 17 pb−1 for φ-region, and ∼ 82 pb−1 above φ.
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