Pion light-by-light contributions to the muon $g-2$

Understand

This paper contains some new results on the hadronic light-by-light contribution (HLbL) to the muon $g-2$.

• The first part argues that we can expect large effects from disconnected diagrams in present and future calculations by lattice QCD of HLbL.
• The argument is based on the dominance of pseudo-scalar meson exchange.
• In the second part, we revisit the pion loop HLbL contribution to the muon anomalous magnetic moment.