Anomalous magnetic moment of the muon: A hybrid approach

A new QCD sum rule determination of the leading order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, aμhvp, is proposed. This approach combines data on e+e− annihilation into hadrons, perturbative QCD and lattice QCD results for the first derivative of the electromagnetic current correlator at zero momentum transfer, ΠEM′(0). The idea is based on the observation that, in the relevant kinematic domain, the integration kernel K(s), entering the formula relating aμhvp to e+e− annihilation data, behaves like 1/s times a very smooth function of s, the squared energy. We find an expression for aμ in terms of ΠEM′(0), which can be calculated in lattice QCD. Using recent lattice results we find a good approximation for aμhvp, but the precision is not yet sufficient to resolve the discrepancy between the R(s) data-based results and the experimentally measured value.