Hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon at the physical pion mass

We present a lattice quantum chromodynamics (QCD) calculation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon using <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>N</a:mi><a:mi>f</a:mi></a:msub><a:mo>=</a:mo><a:mn>2</a:mn><a:mo>+</a:mo><a:mn>1</a:mn><a:mo>+</a:mo><a:mn>1</a:mn></a:math> flavors of staggered quarks with masses tuned to their physical values. Our final result, in the continuum limit, reads <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msubsup><c:mi>a</c:mi><c:mi>μ</c:mi><c:mrow><c:mi>hlbl</c:mi></c:mrow></c:msubsup><c:mo>=</c:mo><c:mn>125.5</c:mn><c:mo stretchy="false">(</c:mo><c:mn>11.5</c:mn><c:msub><c:mo stretchy="false">)</c:mo><c:mrow><c:mi>stat</c:mi></c:mrow></c:msub><c:mo stretchy="false">(</c:mo><c:mn>1.9</c:mn><c:msub><c:mo stretchy="false">)</c:mo><c:mrow><c:mi>syst</c:mi></c:mrow></c:msub><c:mo>×</c:mo><c:msup><c:mn>10</c:mn><c:mrow><c:mo>−</c:mo><c:mn>11</c:mn></c:mrow></c:msup></c:math> where the first error is statistical and the second is systematic. Light, strange, and charm-quark contributions are considered. In addition to the connected and leading disconnected contributions, we also include an estimate of the subleading disconnected diagrams. Our result is compatible with previous lattice QCD and data-driven dispersive determinations.