Monday, May 13, 2024

Tauonium: The smallest and heaviest atom with pure electromagnetic interaction

Amazing stuff! How esoteric?

"... To date, only two types of atoms with pure electromagnetic interactions have been discovered: the electron-positron bound state discovered in 1951 and the electron-antimuon bound state discovered in 1960. Over the past 64 years, there have been no other signs of such atoms with pure electromagnetic interactions, although there are some proposals to search for them in cosmic rays or high-energy colliders.
Tauonium, composed of a tauon and its antiparticle, has a Bohr radius of only 30.4 femtometers (1 femtometer = 10-15 meters), approximately 1/1,741 of the Bohr radius of a hydrogen atom. This implies that tauonium can test the fundamental principles of quantum mechanics and quantum electrodynamics at smaller scales, providing a powerful tool for exploring the mysteries of the micro-material world. ...
This achievement serves as one of the most important physical objectives of the proposed Super Tau-Charm Facility (STCF) in China or the Super Charm-Tau Factory (SCTF) in Russia"

From the abstract (it contains graphics, which were not copied):
"QED atoms are composed of unstructured and point-like lepton pairs bound together by the electromagnetic force. The smallest and heaviest QED atom is formed by a  pair. Currently, the only known atoms of this type are the and  atoms, which were discovered 64 years ago and remain the sole examples found thus far. We demonstrate that the  (atom with) atom signal can be observed with a significance larger than  including both statistical and systematic uncertainties, via. the process Ɇ (, or, and Ɇ is the missing energy due to unobserved neutrinos) with  data taken around the  pair production threshold. The  lepton mass can be measured with a precision of 1 keV with the same data sample. This is within one year’s running time of the proposed super tau-charm facility in China or super charm-tau factory in Russia."

Tauonium: The smallest and heaviest atom with pure electromagnetic interaction



Graphical abstract


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