This is a follow-up for the question Is the helium atom with only a contact interaction between the electrons solvable?. I doubt that there would be a positive answer to that. But I'm interested in any model, which has the following features:
- Is exactly solvable analytically
- Can be formulated as a Schrödinger equation in position representation
- Has bound states in continuum, like helium atom without electron-electron repulsion
- These bound states can be converted to resonances by addition of an interaction term to the Hamiltonian, without rendering the model unsolvable.
Are there any such models?
