Antiprotonic atoms containing antiproton

There is a kind of atom where the nuclear effects are very large - exotic atoms, containing hadrons, i.e. particles that can interact strongly pions, antiprotons, kaons etc. In such atoms any advanced high-accurate QED theory is not necessary and a goal to study such atoms is to measure these nuclear parameters. An important feature of any spectroscopic measurement is its high accuracy in respect to non-spectroscopic methods. That is very important for exotic atoms, because some, like e.g. pionium (7r+7r -system or bound 7rp-system), are available in very small quantities (a few hundreds) [35],... 

Nearly all the ordinary chemical properties of matter can be explained in terms of atoms consisting of electrons, protons, and neutrons. The discussion of atomic structure that follows is based on the assumption that atoms contain only these principal subatomic particles. Many other subatomic particles, such as mesons, positrons, neutrinos, and antiprotons, have been discovered, but it is not yet clear whether all these... 

The list of simple atoms accessible now includes a broad range of very different natural and artificial systems hydrogen, helium, muonium, positronium, various few-electron ions, muonic atoms and exotic atomic systems containing a pion, antiproton etc. While hydrogen atoms form the essential part of our universe, the unstable atoms like muonium do not exist in nature at all. The investigation of simple atoms has provided us with important knowledge on fundamental interactions between the particles these atoms consist of. 

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