  In this paper we compute classical Minkowsky spacetime solutions of pure
SU(2) and SU(3) gauge theories, in Landau gauge. The solutions are regular
everywhere except at the origin and/or infinity, are characterized by a four
momentum $k$ such that $k^2 = 0$ and resemble QED configurations. The classical
solutions suggest a particle-independent description of hadrons, similarly to
the Atomic and Nuclear energy levels, which is able to reproduce the heavy
quarkonium spectrum with a precision below 10%. Typical errors in the
theoretical mass prediction relative to the measured mass being of the order of
2-4%.
