Infrared catastrophe for Nelson's model -- non-existence of ground state and soft-boson divergence (Q998129)

Summary: We mathematically study the infrared catastrophe for the Hamiltonian of Nelson's model when it has the external potential in a general class. For the model, we prove the pull-through formula on ground states in operator theory first. Based on this formula, we show both non-existence of any ground state and divergence of the total number of soft bosons.