Erratum to "Measurement of the $e^+e^-\to\pi^+\pi^-$ cross section between 600 and 900 MeV using initial state radiation"

TL;DR

This erratum corrects the statistical error evaluation in a previous BESIII measurement of the $e^+e^- o \pi^+\pi^-$ cross section between 600 and 900 MeV, refining the uncertainty in the muon's anomalous magnetic moment contribution.

Contribution

It provides a corrected statistical error analysis and updated uncertainty for the hadronic vacuum polarization contribution to the muon g-2, improving the precision of previous results.

Findings

Reduced statistical uncertainty in muon g-2 contribution

No change in central values of cross section and systematic errors

Enhanced accuracy of error propagation in the measurement

Abstract

In Phys. Lett. B 753, 629-638 (2016) [arXiv:1507.08188] the BESIII collaboration published a cross section measurement of the process $e^+e^-\to \pi^+ \pi^-$ in the energy range between 600 and 900 MeV. In this erratum 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 $a_\mu^{\pi\pi\mathrm{, LO}}(600 - 900\,\mathrm{MeV}) = (368.2 \pm 1.5_{\rm stat} \pm 3.3_{\rm syst})\times 10^{-10}$. The central values of the cross section measurement and of $a_\mu^{\pi\pi\mathrm{, LO}}$, as well as the systematic uncertainties remain unchanged.