Experiments at DAΦNE-Frascati and at J-PARC are scheduled to produce K−D atoms and observe their X-ray cascade down to the 1S ground state (g.s.), thereby measuring its strong-interaction width and shift away from a purely Coulomb state. A width Γ1S≲1 keV will ensure good resolution of the X-ray transitions feeding the 1S g.s. Here we study the expected K−D 1S g.s. width from the perspective of global fits to level shifts and widths in heavier kaonic atoms across the periodic table, using K− nuclear optical potentials constructed from K¯N chiral interaction models. Special attention is paid to the subthreshold energy at which the K¯N subsystem interacts in the K−D atom g.s. Within this approach we predict strong-interaction upward level shift of close to 700 eV and width of about 1.2 to 1.3 keV for the K−D atom 1S g.s., in fair agreement with genuinely three-body K−D atom calculations. Comparison is made with π−D atom phenomenology.
Bibliographical noteFunding Information:
We thank Zhan-Wei Liu and Wolfram Weise for useful remarks on the previous version. The work of NB was supported by the PAZY Foundation and by the ISF grant No. 1308/16. The work of all three authors is supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No. 824093.
© 2020 Elsevier B.V.
- K-nucleon and K-nucleus interactions near threshold
- Kaonic atoms
- Kaonic deuterium (KD)