Computation of the Disconnected Hadronic Vacuum Polarization Contribution to the Anomalous Magnetic Moment of Muon*

The search for new, fundamental physics beyond the Standard Model includes high-precision tests that compare its predictions with experimental measurements.  The anomalous magnetic moment of the muon is particularly interesting, because its predicted value disagrees with the most recent experimental measurement by about 3σ.  Accordingly, the Fermilab E989 experiment is revisiting this measurement with the goal of reducing the experimental uncertainty by a factor of four.  A comparable reduction in the theoretical uncertainty is therefore needed.  A large part of the theoretical uncertainty comes from the quantum chromodynamic (QCD) contribution.  The QCD contribution is usually divided into two parts -- the hadronic vacuum polarization contribution and the light-by-light scattering contribution.  The former contribution is further divided into "connected" and "disconnected" terms. The disconnected term is especially difficult to calculate, and it contributes a relatively large uncertainty.  In this talk we describe a computation of that contribution to the anomalous magnetic moment of the muon using ab initio methods of lattice QCD, which aims to reduce that uncertainty considerably.