Does every field correspond to a particle?

Question

I know that particles in QFT are just excitations of its corresponding field. But is it possible to have a field which cannot generate particles?

If yes, what terms must be added to the Lagrangian so that particles can be created?

Answer 1

Particles in QFT are an approximate description of a field in regimes where the interaction terms between the particles are weak enough:

http://philsci-archive.pitt.edu/15296/1/qm-continuum%20revised.pdf

Whether the interaction is weak enough depends on what scale you're looking at and what interaction you're looking at. So in some situations the particle approximation won't work and in others it will work. If you want particles you look at your QFT in the weak interaction and large scale limit.