Abstract
We present a first model-independent calculation of intermediate states in the hadronic-light-by-light (HLBL) contribution to the anomalous magnetic moment of the muon that goes beyond the scalar QED pion loop. To this end, we combine a recently developed dispersive description of the HLBL tensor with a partial-wave expansion and demonstrate that the known scalar-QED result is recovered after partial-wave resummation. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box . We then construct a suitable input for the helicity partial waves, based on a pion-pole left-hand cut and show that for the dominant charged-pion contribution, this representation is consistent with the two-loop chiral prediction and the COMPASS measurement for the pion polarizability. This allows us to reliably estimate -wave rescattering effects to the full pion box and leads to our final estimate for the sum of these two contributions .
- Received 26 January 2017
DOI:https://doi.org/10.1103/PhysRevLett.118.232001
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society