New types of clustering structure induced by K⁻ mesons

Novel data from the $K_{\mathrm{stop}}^{-}A$ absorption reaction in light nuclei ^6,7Li and ⁹Be are presented. The study aimed at finding Λt correlations. Regardless of A, the Λt pairs are preferentially emitted in opposite directions. Reaction modeling predominantly assigns to the $K_{\mathrm{stop}}^{-}A\to \Lambda t(N)A^{\prime }$ direct reactions the emission of the Λt pairs whose yield is found to range from 10⁻³ to ${10}^{\mathrm{-4}}/K_{\mathrm{stop}}^{-}$. The experiment was performed with the FINUDA spectrometer at DAΦNE (LNF).

Correlated Λd pairs emitted after the absorption of negative kaons at rest $K_{\mathrm{stop}}^{-}A\to \Lambda d{A}^{\prime }$ in light nuclei ⁶Li and ¹²C are studied. Λ-hyperons and deuterons are found to be preferentially emitted in opposite directions. The Λd invariant mass spectrum of ⁶Li shows a bump whose mass is $3251\pm 6\text{ MeV}/c^2$. The bump mass (binding energy), width and yield are reported. The appearance of a bump is discussed in the realm of the [$\overline{K}3N$] clustering process in nuclei. The experiment was performed with the FINUDA spectrometer at DAΦNE (LNF).