  All the natural forces act through potential fields. Both, the
electromagnetic vector potential and the gravitational potential of the general
relativity are usually deduced starting from general analytic considerations.
However, the nuclear potentials of the weak and strong forces are calculated
experimentally, leading to what is known as phenomenological potentials. That
is to say, expressions requiring adjustments according to the experimental
results. This fact may change if we consider the action as a differential form.
In this case it is possible to deduct some potentials for the nuclear forces
departing from general analytic considerations.
