if erm, for example, i were to produce a beam of pye mesons, which i can do by taking very high energy protons and making them collide with ordinary hydrogen, then the pyon will come out and it will not live for very long, and i think the lifetime of a pyon is something of the order of ten to the minus eight of a second, which means that pyons only live for about one hundred millionth of a second, and these things then decay into othe particles and these other particles are called muons and they decay into  not only do they produce muons, but they produce things called neutrinos and the muons themselves do not live for very long — a muon lives for about two microseconds, which is two millionths of a second — and it decays also into an electron and another neutral particle called a neutrionor, and these neutrinors just are there, they exist very  but they are the end products of these decay processes.