Theory of hybrid state in a metal with a small Fermi surface and strong collective excitations

We develop a theory of a hybrid state. where quasiparticles coexist with strong collective modes, taking as a starting point a model of infinitely many one-dimensional Mott insulators weakly coupled by interchain tunneling. This state exists at an intermediate temperature range and undergoes an antiferromagnetic phase transition at temperatures much smaller than the Mott-Hubbard gap, The most peculiar feature of the hybrid state is that its Fermi surface volume is unrelated to the electron density. We present a self-consistent derivation of the low-energy effective action for our model.