Speaker
Description
The CMD-3 experiment at the VEPP-2000 collider in Novosibirsk carries out a comprehensive study of the exclusive cross-sections of $e^+e^- \to hadrons$ in the center-of-mass energy range from the threshold to $\sqrt{s}<2$ GeV. The energy scan of the whole energy range was performed in 2011-2013 and, after detector and collider upgrade and increase in luminosity by factor 2-3, in 2017-2019. The total luminosity integral collected so far is 200 pb$^{-1}$.
Measurement of the total cross-section of $e^+e^- \to hadrons$, derived as the sum of exclusive channels, provides an important input for the calculation of the hadronic contribution to the muon anomalous magnetic moment. The calculation is strongly dominated by low-energy data, in particular, by data at $\sqrt{s}<2$ GeV. The largest contribution comes from $e^+e^- \to \pi^+\pi^-$ channel, therefore the corresponding cross-section should be measured with sub-percent precision. The new results from CMD-3 are essential for improvement of the reliability of the Standard model calculation, whose accuracy should match the expected precision of the new experiment for measurement of muon $(g-2)$ taking data at Fermilab.
Other interesting topic of the CMD-3 physics program is the detailed study of the hadron cross-sections at the nucleon-antinucleon threshold.
Here we present the survey of results of data analysis, including various modes of electron-positron annihilation with up to seven pions or two kaons and pions in the final state.
