The meson-exchange induced light--by--light contribution to $(g-2)_\mu$   within the nonlocal chiral quark model
  The current status of the muon anomalous magnetic moment (AMM) problem is briefly presented. The corrections to the muon AMM coming from the effects of hadronic light-by-light (LbL) scattering due to light quark-antiquark exchange in pseudoscalar and scalar channels are estimated within the nonlocal chiral quark model (N$\chi$QM). Within this approach the full kinematic dependence on the photon and meson virtualities are taken into account. As a result, the meson exchange contributions to the muon AMM calculated within N$\chi$QM are, in general, smaller than the contributions obtained within other models. The contribution from the scalar channel is positive and small, but stabilizes the combined with pseudoscalar channel result with respect to variation of the model parameters. 
A.E. Dorokhov, A.E. Radzhabov, A.S. Zhevlakov
hep-ph hep-ex hep-lat