Measurement of the e^+e^-→π^+π^- cross section from threshold to 1.2 GeV with the CMD-3 detector
arXiv (Cornell University)(2023)
摘要
The cross section of the process e^+e^-→π^+π^- has been measured in
the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at
the electron-positron collider VEPP-2000. The measurement is based on a full
dataset collected below 1 GeV during three data taking seasons, corresponding
to an integrated luminosity of about 62 pb^-1. In the dominant
ρ-resonance region, a systematic uncertainty of 0.7
energies around ϕ-resonance the π^+π^- production cross section was
measured for the first time with high beam energy resolution. The
forward-backward charge asymmetry in the π^+π^- production has also been
measured. It shows a strong deviation from the theoretical prediction based on
the conventional scalar quantum electrodynamics framework, and it is in good
agreement with the generalized vector-meson-dominance and dispersive-based
predictions. The impact of the presented results on the evaluation of the
hadronic contribution to the anomalous magnetic moment of muon is discussed.
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关键词
threshold,cross section,measurement,e^-\to\pi^
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