Impact of isospin breaking on the distribution of transition probabilities

In the present paper we investigate the effect of symmetry breaking in the statistical distributions of reduced transition amplitudes and reduced transition probabilities. These quantities are easier to access experimentally than the components of the eigenvectors and were measured by Adams er al. [Phys. Lett. B 422, 13 (1998)] for the electromagnetic transitions in Al-26. We focus on isospin symmetry breaking described by a matrix model where both the Hamiltonian and the electromagnetic operator break the symmetry. The results show that for partial isospin conservation, the statistical distribution of the reduced transition probability can considerably deviate from the Porter-Thomas distribution.