title: Hadronic light-by-light scattering contribution to the muon g - 2: an effective field theory approach.
abstract: The hadronic light-by-light contribution to a(mu), the anomalous magnetic moment of the muon, is discussed from the point of view of an effective low-energy theory. As an application, the coefficient of the leading logarithm arising from the two-loop graphs involving two anomalous vertices is computed, and found to be positive. This corresponds to a positive sign for the pion-pole contribution to the hadronic light-by-light correction to a(mu), and to a sizable reduction of the discrepancy between the present experimental value of a(mu) and its theoretical counterpart in the standard model.
authors.affiliation: Centre de Physique Théorique, CNRS-Luminy, Case 907, F-13288 Marseille Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Knecht
authors.forename: A
authors.initials: A
authors.lastname: Nyffeler
authors.forename: M
authors.initials: M
authors.lastname: Perrottet
authors.forename: E
authors.initials: E
authors.lastname: de Rafael