No abstract

The light-by-light contribution to the anomalous magnetic moment of muon (g − 2)µ from the hadronic exchanges in the neutral pseudoscalar meson channel is calculated in the nonlocal chiral quark model. The full kinematic dependence of the meson-two-photon vertices from the virtualities of the mesons and photons is taken into account. The status of various phenomenological and QCD shortdistance constraints is discussed and the comparison with the predictions of other models is performed. It is demonstrated that the effect of the full kinematic dependence in the meson-photon vertices is to reduce the contribution of pseudoscalar exchages to a PS,LbL µ by approximately factor 1.5 in comparison with the most of previous estimates.

The charged wave packets with non-Gaussian spatial profiles are shown to possess intrinsic multipole moments. The magnetic dipole moment and the electric quadrupole moment are found for a wide class of the packets, including the vortex electrons with orbital angular momentum ℓ, the Airy beams, the so-called Schrödinger's cat states, and their generalizations. For the packets with no phase vortices, the electric quadrupole moment is shown to grow quadratically with the packet's width, |Q αβ | ∼ e · σ 2 ⊥ , while it is also |ℓ| times enhanced for the vortex beams. For available beams of electron microscopes, these multipole moments are relatively easily adjusted and can be quite large, which affects the packets' electromagnetic fields and also allows one to develop new diagnostic tools for materials science, atomic and molecular physics, nuclear physics, and so forth.

The electron and muon anomalous magnetic moments (AMM) are measured in experiments and studied in the Standard Model (SM) with the highest precision accessible in particle physics. The comparison of the measured quantity with the SM prediction for the electron AMM provides the best determination of the fine structure constant. The muon AMM is more sensitive to the appearance of New Physics effects and, at present, there appears to be a three-to four-standard deviation between the SM and experiment. The lepton AMMs are pure relativistic quantum correction effects and therefore test the foundations of relativistic quantum field theory in general, and of quantum electrodynamics (QED) and SM in particular, with highest sensitivity. Special attention is paid to the studies of the hadronic contributions to the muon AMM which constitute the main source of theoretical uncertainties of the SM.