Precise measurements of the hadronic cross sections with the CMD-3 and SND detectors at the VEPP-2000e+e−collider

М Н Ачасов ,A.V Bragin,N.S Bashtovoy,V.S Okhapkin,A.V Dimova,D.N Shemyakin,A.E Kuzmenko,A.L Erofeev,A.A Grebenuk,I.B Logashenko,G.P Razuvaev,L.B Epshteyn,B.I Khazin,S.E Gayazov,N.M Ryskulov,R.R Akhmetshin,A.E Ryzhenenkov,D.N Grigoriev,K Mikhailov ,V.sh Banzarov ,F.V Ignatov,Л.м Барков ,D Epifanov ,E A Kozyrev ,P Lukin ,D Shtol ,A E Obrazovsky ,S V Karpov ,А.а Рубан ,Alexander Romanov ,A Barnyakov ,A V Anisenkov ,I M Zemlyansky ,Alexei Talyshev ,А Г Богданчиков ,A V Berdyugin ,A Kuzmin ,D P Kovrizhin ,V Shebalin ,Yu A Rogovsky ,Yu V Yudin ,Yu S Popov ,Е В Пахтусова ,D E Berkaev ,Y Pestov ,В Ф Казанин ,I K Surin ,E A Perevedentsev ,S Eidelman ,A Kupich ,P Krokovny ,A V Vasiljev ,А П Лысенко ,A.V Otboev,D B Shwartz ,A G Kharlamov ,P Yu Shatunov ,V Aulchenko ,E M Gromov ,O A Kovalenko ,А.і Воробйов ,A A Korol ,K Beloborodov ,В.м Титов ,Yu M Shatunov ,L Kardapoltsev ,V P Druzhinin ,E P Solodov ,A Sibidanov ,S V Koshuba ,K A Martin ,A N Kirpotin ,I A Koop ,B Shwartz ,G V Fedotovich ,A Bondar ,Aleksei Kozyrev ,З К Силагадзе ,A A Botov ,А С Попов ,K Grevtsov ,S I Serednyakov ,V B Golubev ,Yu M Zharinov

doi:10.1051/epjconf/20147100121

Abstract

It’s good known the difference in 3.5 sigma between the muon (g – 2) experimental result and its calculation in Standard Model. To clarify this intriguing discrepancy the new stage of muon (g – 2) measurement is under preparation at Fermi National Laboratory. On other hand, regular data taking for measurements of hadron cross section production in e + e − annihilations is under way since December 2010 at the electron-positron collider VEPP-2000 with the CMD-3 and SND detectors. The collected data sample corresponds to about 60 inverse picobarns of integrated luminosity per detector in the energy range from 0.32 up to 2 GeV. Preliminary analysis of various hadronic cross sections has been performed.

Highlights

The electron-positron collider VEPP-2000 [1, 2] has been operating at Budker Institute of Nuclear Physics since 2010
The goal of the CMD-3 experiment is to reduce a systematic uncertainty on this channel to 0.35%
The geometry of this process allows a clean selection of e+e−, μ+μ−, π+π− collinear events to be performed practically without physical background

Summary

Introduction

The physics program [6] includes high precision measurements of the e+e− → hadrons cross sections in the wide energy range up to 2 GeV, studies of known and searches for new vector mesons, studies of nnand ppproduction cross sections near threshold and searches for exotic hadrons. It requires detectors with high efficiency for multiparticle events and good energy and angular resolution for charged particles as well as for photons. The new positron injection facility and achieved operational experience will improve the situation at low energy

Pion formfactor

Multipion production

Nucleons near threshold

Conclusions