  The original Standard Model has massless neutrinos, but the observation of
neutrino oscillations requires that neutrinos are massive. The simple extension
of adding gauge singlet fermions to the particle spectrum allows normal Yukawa
mass terms for neutrinos. The seesaw mechanism then suggests an explanation for
the observed smallness of the neutrino masses. After reviewing the framework of
the seesaw we suggest a parametrization that directly exhibits the smallness of
the mass ratios in the seesaw for an arbitrary number of singlet fermions and
we present our plans to perform calculations for a process that might be
studied at the LHC.
