The lighter particles such as electrons, neutrinos, and muons are collectively called leptons, while the heavier particles that are nuclear particles and products of their interactions such as protons, neutrons, and prions are collectively called hadrons. As well as the muon and tau particles that are negatively charged we have a very common particle called the neutrino that has no charge.
We then get combinations of the neutrino with the electron, tau, or muon, as for example the muon neutron, to give further particles with no charge. In particular, fermions refer to the class of particles with one type of spin, while bosons both elementary and composite refer to those with another type. There is also a close relationship between the strong force and the relative masses of the elementary particles.
The energy density of empty space currently related to the cosmological constant, though still controversial has a precise value. The cosmological constant is the result of the almost perfect cancellation of a very large number of comparatively very large physical constants. For example, a change in the strength of the gravitational or nuclear force by as little as one part in 10100 could entirely ruin the cancellation, making space expand or contract furiously.