Transition strength sums and quantum chaos - art. no. 051306

For the embedded Gaussian orthogonal ensemble of random matrices, the stren gth sums generated by a transition operator acting on an eigenstate vary wi th the excitation energy as the ratio of two Gaussians. This general result is compared to exact shell-model calculations of Gamow-Teller strength sum s in nuclei. Good agreement is obtained in the chaotic domain of the spectr um, and strong deviations are observed as nuclear motion approaches a regul ar regime. Thus transition strength sums seem to be a new statistic sensiti ve to the chaoticity of the system. [S0556-2813(99)51411-8].