Multi-$\bar{K}$ nuclei and kaon condensation

TL;DR

This paper extends relativistic mean-field calculations to multi-antikaon nuclei, finding saturation of binding energies and densities, and argues that kaon condensation is unlikely in strange hadronic matter, while exploring possible self-bound systems.

Contribution

It introduces a robust RMF model for multi-antikaon nuclei, demonstrating saturation effects and challenging the likelihood of kaon condensation in strange matter.

Findings

$ar K$ separation energy saturates for $ar K$ number > 10

Saturation is robust across different models and mediating fields

Kaon condensation unlikely in strong-interaction strange matter

Abstract

We extend previous relativistic mean-field (RMF) calculations of multi-$\bar K$ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting $\bar K$ separation energy $B_{\bar K}$, as well as the associated nuclear and $\bar K$-meson densities, saturate with the number $\kappa$ of $\bar K$ mesons for $\kappa > \kappa_{\rm sat} \sim 10$. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because $B_{\bar K}$ generally does not exceed 200 MeV, it is argued that multi-$\bar K$ nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and ${\bar K}^0$ mesons, or protons and $K^-$ mesons, and study their properties.