Lattice calculation of the hadronic leading order contribution to the muon $g-2$

The persistent discrepancy of about 3.5 standard deviations between the experimental measurement and the Standard Model prediction for the muon anomalous magnetic moment, a µ , is one of the most promising hints for the possible existence of new physics. Here we report on our lattice QCD calculation of the hadronic vacuum polarisation contribution , based on gauge ensembles with N f = 2 + 1 flavours of O(a ) improved Wilson quarks. We address the conceptual and numerical challenges that one encounters along the way to a sub-percent determination of the hadronic vacuum polarisation contribution. The current status of lattice calculations of is presented by performing a detailed comparison with the results from other groups.