Magnetic hyperfine structure of muonic and electronic atoms

The magnetic hyperfine structure of atoms is studied. A new compact expression is introduced for the magnetic hyperfine anomaly. A theoretical foundation is given for an empirical formula discovered by Moskowitz and Lombardi. The effects of core polarization and mesonic exchange currents are discussed. There are two kinds of core polarization, Δl = 0 and Δl = 2. The latter is shown to be important to explain certain isotope shifts, though it is smaller than the former Δl = 0 effect.