Invariant-Mass Spectroscopy for Condensed Single- and Double-kbar Nuclear Clusters to be Formed as Residues in Relativistic Heavy-Ion Collisions

Using a phenomenological \={K}N interaction combined with the method of Antisymmetrized Molecular Dynamics., we predict that few-body double-\kbar nuclei, such as ppK$^-$K$^-$ and ppnK$^-$K$^-$, as well as single-\kbar nuclei, are tightly bound compact systems with large binding energies and ultra-high nucleon densities. We point out that these \kbar nuclear clusters can be produced as residual fragments in relativistic heavy-ion collisions and that their invariant masses can be reconstructed from their decay particles.