An exotic atom is an atom that has a particle replaced by a particle of the same charge. For example, Positronium, an exotic atom, contains an electron and a positron. The positron (which is the antiparticle of the electron) replaces a proton which would normally be found in that atom. Most exotic atoms are hard to discover, because they decay very quickly. Positronium on average has a half-life (how long until half of the object is gone via decay) of 0.125 nanoseconds. There are a few types of exotic atom.
Muonic atom[change | change source]
Hadronic atom[change | change source]
A hadronic atom is an exotic atom that has an electron replaced by a negatively charged hadron. The hadron could be a meson (such as a pion or a kaon, creating a pionic atom or a kaonic atom, respectively). Another hadronic atom is an antiproton (antiparticle of the proton) atom, that has an antiproton replacing an electron. This is known as an antiprotonic atom.
Onium[change | change source]
An onium is an exotic atom that has a particle bound to its antiparticle. A good example is Positronium, which is an electron bound to a positron.
Hypernuclear atom[change | change source]
A hypernuclear atom is an exotic atom that contains strange particles (a particle that is made of a strange quark) called hyperons.