Double beta-decay and su(4) symmetry

The amplitude for tiff decay with 2v emis- sion is shown to be related to (p, n) and (n, p) reactions on the initial and final states, respectively. The sup- pression of both tiff and (n,p) reaction is connected, and its origin is discussed by referring to the SU(4) symmetry. From present data on the first ones, we estimate the forward (n, p) strength of relevance for the tiff problem. The interest of the experimental deter- mination of this strength is emphasized. Assuming a perturbative breaking of the SU(4) symmetry, results are given for 76Ge, 828e, 128Te and 13~