  We develop a theory of a hybrid state, where quasi-particles coexist with
strong collective modes, taking as a starting point a model of infinitely many
1D Mott insulators coupled by a weak 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 the volume of the Fermi surface is
unrelated to the electron density. We present a self-consistent derivation of
the low energy effective action for our model.
