Abstract
Within a dispersive approach to hadronic light-by-light scattering in the muon , the evaluation of the numerically dominant pseudoscalar-pole contribution involves the pseudoscalar-photon transition form factor with and, in general, two off-shell photons with spacelike momenta . We show that for , the region of photon momenta below about 1(1.5) GeV gives the main contribution to hadronic light-by-light scattering. We then discuss how the precision of current and future measurements of the single- and double-virtual transition form factor in different momentum regions impacts the precision of a data-driven estimate of this contribution to hadronic light-by-light scattering. Based on Monte Carlo simulations for a planned first measurement of the double-virtual form factor at BESIII, we find that for the -pole contributions a precision of 14%, 23%, 15% seems feasible. Further improvements can be expected from other experimental data and also from the use of dispersion relations for the different form factors themselves.
- Received 14 June 2016
DOI:https://doi.org/10.1103/PhysRevD.94.053006
© 2016 American Physical Society