Intensity correlations between the components of the resonance fluorescence triplet

We present a theoretical analysis of the intensity correlations between the spectral components of the resonance fluorescence triplet while allowing for detection time differences that are smaller than the inverse frequency width of the frequency filter. Explicit expressions are derived for the intensity correlation functions that are valid for all times. Furthermore, we present the results of measurements on these correlation functions for the ${}_{}{}^1{}_{}{}^{}$ ${\mathit{S}}_0$ ${\mathrm{\leftrightarrows }}^1$ ${\mathit{P}}_1$ resonance transition of natural barium. In general, the results confirm the theoretical predictions.