Determination of the charged kaon mass by laser spectroscopy of kaonic helium atoms at DAPHNE

by Masaki Hori (Imperial College London)

Wednesday 5 Mar 2025, 14:30 → 16:45 Europe/Rome

Aula Salvini (Laboratori Nazionali di Frascati)

We propose the first laser spectroscopy of an atom containing a kaon at DAPHNE, which may eventually allow the precision on the charged kaon mass to be improved by 2 to 3 orders of magnitude compared to now, and establish upper limits on beyond-the-standard model forces that may arise between kaons and the other constituent particles of the atom.  Metastable kaonic helium is a three-body atom consisting of a helium nucleus, an electron, and kaon occupying a Rydberg state. The atom has an anomalously long lifetime of 10 ns which makes it amenable to laser spectroscopy.  Quantum electrodynamics calculations for these atoms currently achieve parts-per-billion scale precision. We have carried out similar experiments at the Antiproton Decelerator of CERN for many years and determined the antiproton-to-electron mass ratio to a precision of 8 parts in 10^10; laser spectroscopy of pionic helium atoms which have a lifetime of 7 ns was also recently achieved at the 590 MeV/c ring cyclotron facility of Paul Scherrer Institute.  This increases our confidence that laser spectroscopy of the kaonic variety is now possible, utilizing the modern advances in laser technology. The experiment critically relies on the low-energy kaons of small energy spread which are only available at DAPHNE. Some of the technical challenges of achieving this goal in DAPHNE will be described.

Locandina_Hori.docx