  We study the dynamical spin response of doped two-leg Hubbard-like ladders in
the framework of a low-energy effective field theory description given by the
SO(6) Gross Neveu model. Using the integrability of the SO(6) Gross-Neveu
model, we derive the low energy dynamical magnetic susceptibility. The
susceptibility is characterized by an incommensurate coherent mode near
$(\pi,\pi)$ and by broad two excitation scattering continua at other
$k$-points. In our computation we are able to estimate the relative weights of
these contributions.
  All calculations are performed using form-factor expansions which yield exact
low energy results in the context of the SO(6) Gross-Neveu model. To employ
this expansion, a number of hitherto undetermined form factors were computed.
To do so, we developed a general approach for the computation of matrix
elements of semi-local SO(6) Gross-Neveu operators. While our computation takes
place in the context of SO(6) Gross-Neveu, we also consider the effects of
perturbations away from an SO(6) symmetric model, showing that small
perturbations at best quantitatively change the physics.
