JRP – Hadronic light-by-light contribution to g-2

Project leaders


By a joint effort of experimental input, dispersive analyses and lattice calculations, we will constrain the  HLbL contribution to \((g-2)_\mu\) to the precision level targeted by the Fermilab and future J-PARC experiments.

Since the hadronic corrections, HLbL and the hadronic vacuum polarization (HVP), entirely dominate the uncertainty of the Standard Model prediction for \((g-2)_\mu\) at present, their improved determination will have a direct impact on the interpretation of the measurements at Fermilab and J-PARC, which aim at a fourfold increase in precision. The improvement of the HLbL contribution to 10 % accuracy, accompanied by a re-assessment of the HVP, is crucial to enable a discovery based on this precision observable.