Final answer:
Muons and tau particles are not found in ordinary matter because they are unstable and decay rapidly via the weak force. They do not interact with the strong nuclear force, which binds protons and neutrons in atomic nuclei.
Step-by-step explanation:
The muon and tau particles are not found in ordinary matter because they are unstable and decay quickly to lighter particles via the weak force. Unlike the proton, neutron, and electron, which are stable and make up ordinary matter, muons and tau particles have much shorter lifespans. Muons, for instance, have a mass of about 106 MeV/c² and were initially believed to be the particle predicted by Yukawa, which would interact via the strong nuclear force. However, it was later understood that muons do not feel the strong nuclear force and cannot be a part of atomic nuclei in the same way as protons and neutrons.
The tau particle is approximately 3500 times heavier than the electron but similar to the muon and electron in some ways. However, due to its even shorter lifetime than the muon, it decays even more quickly and is thus even less likely to be encountered in ordinary matter. These particles are typically produced in high-energy environments, such as cosmic ray interactions or in particle accelerators, rather than being a part of stable matter.