Evaluation of the three-flavor quark-disconnected contribution to the moon anomalous magnetic moment from experimental data

We point out that the sum of the strange-quark-connected and full three-flavor quark-disconnected contributions to the leading-order hadronic vacuum polarization contribution, a(mu)(LO,HVP), to the anomalous magnetic moment of the muon is a physical observable, and we provide a data-based determination of this quantity in the isospin limit. The result, 40.1(1.5) x 10(-10) or 38.7(2.0) x 10(-10), depending on which data compilation is used, serves as a target of comparison for lattice calculations of the same isospin-limit combination. Subtracting from this result the average of lattice determinations of the strange-quark-connected contribution, one also obtains an alternate determination of the isospin-limit three-flavor disconnected contribution to a(mu)(LO,HVP). The result of this determination, -13.3(1.5) x 10(-10) or -14.6(2.0) x 10(-10), depending on which data compilation is used, agrees well and is competitive with the most precise current lattice determination.