The cosmological origin of the Nambu-Jona-Lasinio model
  Recently a mechanism to generate mass from gravitational interaction, based
on Mach principle, according to which the inertia of a body is a property of
matter as well as of the background provided by the rest-of-the-universe was
presented in \cite{novello} \cite{novello2}. In these papers such an idea was
realized for scalar and spinor fields treating the rest-of-the-universe in its
vacuum state. In the present paper, using an extended version of Mach
principle, the same strategy will be applied to show how the
Heisenberg-Nambu-Jona-Lasinio non-linear equation for fermions $\Psi$ arises as
a consequence of the gravitational interaction of $ \Psi$ with the
rest-of-the-universe.
