Calculations of $K^-$ nuclear quasi-bound states based on chiral meson-baryon amplitudes

TL;DR

This paper uses a chiral coupled-channel model to calculate $K^-$ nuclear quasi-bound states, revealing large absorption widths that challenge their experimental detection, especially in heavier nuclei.

Contribution

It presents a self-consistent calculation of $K^-$ nuclear quasi-bound states based on a new chiral model, including effects like p-wave interactions and absorption modes.

Findings

Potential depths of 80-120 MeV for $K^-$

Absorption widths larger than binding energies

Detection unlikely in heavy nuclei due to broad widths

Abstract

In-medium ${\bar K}N$ scattering amplitudes developed within a new chirally motivated coupled-channel model due to Cieply and Smejkal that fits the recent SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct $K^-$ nuclear potentials for calculations of $K^-$ nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to $K^-$ potential depths $-Re V_K \approx 80 -120$ MeV. Self-consistent calculations of all $K^-$ nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon $K^-NN\rightarrow YN$ absorption modes are discussed. The $K^-$ absorption widths $\Gamma_K$ are comparable or even larger than the corresponding binding energies $B_K$ for all $K^-$ nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for $K^-$ nuclear quasi-bound states in any but lightest nuclear systems.