Antikaon hydrogen atoms offer an ideal framework to study strong-interaction processes, allowing to perform experiments at vanishing relative energies between the antikaon and the nucleon, which will give access to the basic low-energy parameters, like the antikaon-nucleon scattering lengths. The antikaon hydrogen reaction is well understood from the recent results obtained from KpX at KEK, DEAR and finally from SIDDHARTA at DAFNE, along with theoretical calculations based on these results.
The importance of antikaon deuterium atom X-ray spectroscopy has been well recognized, no experimental results have yet been obtained due to the difficulty of the X-ray measurement. The kaonic deuterium measurement, is indeed needed to disentangle the isoscalar and isovector complex scattering length, shedding light on the antikaon-neutron interaction, long-awaited by theory.
The planned antikaon deuterium experiment at Laboratori Nazionali di Frascati (Italy) and at the Japan Proton Accelerator Research Complex (J-PARC, Japan) will be described, including first test measurements at J-PARC with the new developed X-ray spectroscopy device.