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arXiv · 2010.09455

On the width of the $K^-$D atom ground state

N. Barnea·E. Friedman·A. Gal
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Abstract

Experiments at DA$Φ$NE-Frascati and at J-PARC are scheduled to produce $K^-$D atoms and observe their X-ray cascade down to the 1$S$ ground state (g.s.), thereby measuring its strong-interaction width and shift away from a purely Coulomb state. A width $Γ_{1S}\lesssim 1$ keV will ensure good resolution of the X-ray transitions feeding the 1$S$ g.s. Here we study the expected $K^-$D 1$S$ 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 $\bar K N$ chiral interaction models. Special attention is paid to the subthreshold energy at which the $\bar K N$ subsystem interacts in the $K^-$D atomic 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 1$S$ g.s., in fair agreement with genuinely three-body $K^-$D atom calculations. Comparison is made with $π^-$D atom phenomenology.

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N. Barnea, E. Friedman, A. Gal. 2020-12-04. On the width of the $K^-$D atom ground state. https://doi.org/10.1016/j.nuclphysa.2020.122112

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