  In this paper we develop a theoretical framework which allows us to study
excitations of the nucleon. Assuming an effective two-body interaction as a
model for low-energy QCD, we derive a relativistic TDHF equation for a
many-body system of quarks. To render the Dirac-sea contribution tothe mean
field finite, we introduce a symmetry conserving regularization scheme. In the
small amplitude limit we derive an RPA equation. The structure of the $ph$
interaction and modifications due to the regularization scheme are discussed.
We give a prescription to obtain a nucleon state with good angular momentum (J)
and isospin (T) quantum numbers on mean-field level. To study excitations, we
develop a tensor-RPA approach, which is an extension of the conventional RPA
techniques to systems with a nonscalar ground state. This allows us to
construct excited states with good (J/T) quantum numbers. We discuss a method
to reduce the overcomplete $ph$-space and compute the tensor-RPA interaction
matrix elements. Finally we extend our scheme to include ({3/2}^+,
{3/2})-states.
