Hyperfine interaction in excited states of rubidium and cesium: $S$ states

The one-electron contributions to the hyperfine constants for the excited $S$ states of rubidium and cesium are calculated and compared with recent experimental results. From this comparison, the expected many-body contributions to the hyperfine constants are derived and shown to systematically decrease for higher excited states, in agreement with the situation found in earlier work on sodium. The physical origin of this behavior of the correlation effect is discussed.