FLUCTUATION PROPERTIES OF STRENGTH FUNCTION PHENOMENA - A MODEL STUDY

We study fluctuation properties of strength function phenomena by empl oying a quantum mechanical model where a single parent state couples w ith a large number of background states. The background system is devi sed in such a way that the classical dynamics of the system may show a regular, an irregular, or a chaotic character as a function of a sing le parameter. The coupling of the parent state to the background state s produces a fragmentation of the parent state, giving rise to a stren gth function phenomenon. We study various measures of the strength fun ction that characterize its bulk structure or fluctuation properties. They include energy moments, strength distribution, fractal dimensions of the strength function, and Fourier transform of the autocorrelatio n function. Some of these measures, such as strength distribution or F ourier transform of the autocorrelation function, reflect characterist ic aspects of the dynamics of the background system, i.e., if they hav e a regular or a chaotic character, while measures such as energy mome nts or fractal dimensions are rather insensitive to the dynamics.