The Many Guises of a Neutral Fermion Singlet

Understand

The addition of a neutral fermion singlet to the standard model of particle interactions leads to many diverse possibilities.

• It is not necessarily a right-handed neutrino.
• I discuss many of the simplest and most interesting scenarios of possible new physics with this approach.
• In particular I propose the possible spontaneous breaking of baryon number, resulting in the massless 'sakharon'.