ABSTRACT
The “standard model” consists of a set of quantum field theories that describe all the known fundamental forces except gravity. The elementary particles that form the players in these theories are often listed in a table, organized according to the interactions in which they take part. The nuclear physics and particle physics communities are distinct. Nuclear physicists, true to their name, study the properties of nuclear matter. Although their principle preoccupation is with the theory of quantum chromodynamics, they frequently use nuclear systems to investigate physics beyond the standard model. The masses of the elementary particles are also not listed in the table. In the case of the neutrinos, only upper limits on the masses are known. They were treated as massless, but one of the major accomplishments in experimental particle physics was the discovery that the probability of obtaining a certain type of neutrino upon measurement varies as the neutrino travels along its way.
