The antikaon-nucleon (K-N) interactions close to threshold provide information to the interplay between spontaneous and explicit chiral symmetry breaking in low-energy QCD. We propose to measure the strong-interaction level shift and width of the kaonic deuterium 1s state with an accuracy of about 70 eV and 170 eV, respectively, in the SIDDHARTA-2 experiment. Together with the results of the shift and width of the kaonic hydrogen 1s state obtained by the SIDDHARTA experiment, it will be able to determine both the isospin I=0 and I=1 antikaon-nucleon scattering lengths, for the first time.
Based on a first test measurement of kaonic deuterium in the SIDDHARTA experiment, new design of the experimental setup was developed in order to observe the kaonic deuterium X-rays with a good signal-to-background ratio. Compared to the data taken in the SIDDHARTA, detailed Monte Carlo studies were performed to investigate the background suppression factors in the new setup. The feasibility of the determination of shift and width of the kaonic deuterium 1s state was found.
Although the importance of the kaonic deuterium X-ray spectroscopy in the field of low-energy antikaon-nucleon interactions has been well recognized, no experimental results were obtained up to now. SIDDHARTA-2 is a unique experiment of kaonic deuterium; no other proposals exist. The results of SIDDHARTA-2 provide the most stringent constraints on the antikaon-nucleon interaction, promising a breakthrough for this field.
SMI will develop the target and veto systems used in the SIDDHARAT-2 experiment. The costs of these systems are requested to be funded by FWF.