Theoretical analysis of the possible ultra-low-Q-value decay branch of 135Cs

We have investigated the feasibility of observing an ultra-low-Q-value beta-decay branch of 135Cs by applying the microscopic quasiparticle-phonon model with a realistic two-body nuclear interaction. This work was motivated by an earlier combined experimental and theoretical work on decays of 115In. The inaccuracy of the ground-state-to-ground-state Q value limits our ability to draw definite conclusions, and therefore modern precision measurements for it are called for. We present the computed partial half-lives of each channel for the most likely ranges of Q values.