I'm dealing with the problem of zero frequencies in many body system and it's relation with symmetry breaking. I would like to examine this connection in the case of quantum shape-phase transition in nuclei. I've studied this technique (golstone theorem) in field theory as well as Particle physics but I am interested in finding zero-frequency modes in many-body system (such as multiple oscillators which are coupled in a circle or nucleons in finite nuclei ). Please help me to find an appropriate source .