In a previous paper we investigate a Lagrangian field theory for the
gravitational field (which is there represented by a section g^a of the
orthonormal coframe bundle over Minkowski spacetime. Such theory, under
appropriate conditions, has been proved to be equivalent to a Lorentzian
spacetime structure, where the metric tensor satisfies Einstein field
equations. Here, we first recall that according to quantum field theory ideas
gravitation is described by a Lagrangian theory of a possible massive graviton
field (generated by matter fields and coupling also to itself) living in
Minkowski spacetime. The graviton field is moreover supposed to be represented
by a symmetric tensor field h carrying the representations of spin two and zero
of the Lorentz group. Such a field, then (as it is well known), must
necessarily satisfy the gauge condition given by Eq.(3) below. Next, we
introduce an ansatz relating h to the 1-form fields g^a. Then, using the
Clifford bundle formalism we derive, from our Lagrangian theory, the exact wave
equation for the graviton and investigate the role of the gauge condition given
by Eq.(3) in obtaining a reliable conservation law for the energy-momentum
tensor of the gravitational plus the matter fields in Minkowski spacetime.
Finally we ask the question: does Eq.(3) fix any gauge condition for the field
g of the effective Lorentzian spacetime structure that represents the field h
in our theory? We show that no gauge condition is fixed a priory, as is the
case in General Relativity. Moreover we investigate under which conditions we
may fix Logunov gauge condition.Comment: 15 pages. This version corrects some misprints of the published
versio