We determine the contribution to the anomalous magnetic moment of the muon
from the αQED2 hadronic vacuum polarization diagram using
full lattice QCD and including u/d quarks with physical masses for the first
time. We use gluon field configurations that include u, d, s and c
quarks in the sea at multiple values of the lattice spacing, multiple u/d
masses and multiple volumes that allow us to include an analysis of
finite-volume effects. We obtain a result for aμHVP,LO of
667(6)(12), where the first error is from the lattice calculation and the
second includes systematic errors from missing QED and isospin-breaking effects
and from quark-line disconnected diagrams. Our result implies a discrepancy
between the experimental determination of aμ and the Standard Model of
3σ.Comment: 14 pages, 10 figures. Discussion of method extended with additional
tests and figures added. Typographical errors correcte