Intermediate window observable for the hadronic vacuum polarization contribution to the muon g - 2 from O(a) improved Wilson quarks

Following the publication of the new measurement of the anomalous magnetic moment of the muon, the discrepancy between experiment and the theory prediction from the g-2 theory initiative has increased to 4.2 σ. Recent lattice QCD calculations predict values for the hadronic vacuum polarization contribution that are larger than the data-driven estimates, bringing the Standard Model prediction closer to the experimental measurement. Euclidean time windows in the time-momentum representation of the hadronic vacuum polarization contribution to the muon g - 2 can help clarify the discrepancy between the phenomenological and lattice predictions. We present our calculation of the intermediate distance window contribution using Nf = 2 + 1 flavors of O(a) improved Wilson quarks. We employ ensembles at six lattice spacings below 0.1 fm and pion masses down to the physical value. We present a detailed study of the continuum limit, using two discretizations of the vector current and two independent sets of improvement coefficients. Our result at the physical point displays a tension of 3.9 σ with a recent evaluation of the intermediate window based on the data-driven method.