THE HADRONIC LIGHT-BY-LIGHT CONTRIBUTION TO THE MUON ANOMALOUS MAGNETIC MOMENT: WHERE DO WE STAND?

Abstract

We review the status of the hadronic light-by-light contribution to the muon anomalous magnetic moment and critically compare recent calculations. We also study in detail which momentum regions the π 0 exchange main contribution originates. We also argue that [Formula: see text] encompasses the present understanding of this contribution and comment on some directions to improve on that.