Statistical fluctuations of electromagnetic transition intensities and electromagnetic moments in $\mathrm{pf}$-shell nuclei

We study the fluctuation properties of $\Delta T=0\mathrm{}$ electromagnetic transition intensities and electromagnetic moments in $A\sim 60$ nuclei within the framework of the interacting shell model, using a realistic effective interaction for $\mathrm{pf}$-shell nuclei with a ${}^{56}\mathrm{Ni}$ core. The distributions of the transition intensities and of the electromagnetic moments are well described by the Gaussian orthogonal ensemble of random matrices. In particular, the transition intensity distributions follow a Porter-Thomas distribution. When diagonal matrix elements (i.e., moments) are included in the analysis of transition intensities, the distributions remain Porter-Thomas except for the isoscalar $M1.\mathrm{}$ This deviation is explained in terms of the structure of the isoscalar $M1\mathrm{}$ operator.