Abstract
In Ref. [1] the BESIII collaboration published a cross section measurement of the process e+e−→π+π− in the energy range between 600 and 900 MeV. In this corrigendum, we report a corrected evaluation of the statistical errors in terms of a fully propagated covariance matrix. The correction also yields a reduced statistical uncertainty for the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, which now reads as aμππ,LO(600−900MeV)=(368.2±1.5stat±3.3syst)×10−10. The central values of the cross section measurement and of aμππ,LO, as well as the systematic uncertainties remain unchanged.
Highlights
We reported [1] a measurement of the cross section σbare(e+e− → π+π−) and the pion form factor |Fπ|2 in the energy range between 600 MeV and 900 MeV
The covariance matrix obtained from the unfolding procedure is propagated taking into account Eqs. 1 and 2 to the level of the bare cross section
∂ σibare ∂k being the Jacobian matrix of the bare cross section with respect to the contribution k to j the statistical uncertainty, according to generalized Gaussian error propagation
Summary
We reported [1] a measurement of the cross section σbare(e+e− → π+π−) and the pion form factor |Fπ|2 in the energy range between 600 MeV and 900 MeV. [2] and [3], there exists a difference between the statistical uncertainties of the tabulated cross section of Ref. When including the covariance matrix, it is not possible to reproduce the fit of the form factor presented in Ref. In scrutinizing the published analysis, we realized that the covariance matrix had been provided at the level of the event yield, not, as claimed, at the level of the cross section. [1] are taken from the event yield prior to unfolding and are propagated to the level of the cross section and form factor, respectively, producing two different statistical uncertainties for the results. The statistical uncertainties are reevaluated and an updated value of the uncertainty of the two-pion contribution to the hadronic vacuum polarization contribution of the anomalous magnetic moment of the muon, aπμπ,LO, is calculated
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