Speaker
fedor ignatov
Description
Regular data taking with the CMD-3 and SND detectors at the VEPP-2000 electron-positron collider in Novosibirsk is underway since 2010. The luminosity up to 10**31 cm-2s-1 has been reached at the energy 2E=2 GeV, and another order of magnitude will be achieved after construction of the new positron source.
The already collected physical data sample corresponds to about 36 inversed picobarns of integrated luminosity in the energy range from phi-meson up to 2 GeV and currently the first scan from 2 pion threshold up to 1 GeV with about 6 pb-1 has been performed to get a new precision measurement of the e+e- -> pi+pi- cross section. Preliminary results on cross sections of a number of multi-hadron final states from CMD3 and SND detectors is reported. The obtained results are in good agreement with previous experiments and have a comparable or better statistical precision.
Besides the study on dynamic of multihadron production, knowledge of e+e- -> hadrons cross-sections with high accuracy at low energies is required to evaluate the hadronic contribution to the anomalous magnetic moment of the muon and the fine structure constant at Z boson mass. While the previous set of experiments allowed the comparison of the muon (g-2) value measured at BNL with SM prediction, revealing more than a 3 sigma difference, the goal on precision of experiments at VEPP-2000 is to match an accuracy of new muon (g-2) measurement at FermiLab and J-PARC.
Primary author
Vladimir Golubev
(Budker Institute of Nuclear Physics)
