Do $\Xi\Xi$ bound states exist?

TL;DR

This study investigates the potential for baryon-baryon bound states in the strangeness sector using SU(3) chiral effective field theory, focusing on the impact of symmetry breaking contact terms and experimental data.

Contribution

It introduces a detailed analysis of SU(3) symmetry breaking effects at next-to-leading order, providing insights into the likelihood of bound states in the S=-2 and ΞΞ systems.

Findings

Decrease of attraction from NN to S=-2 reduces bound state likelihood

No bound state for ΣΣ with isospin I=2 is supported

Bound states in ΞΣ and ΞΞ are unlikely based on trend analysis

Abstract

The existence of baryon-baryon bound states in the strangeness sector is examined in the framework of SU(3) chiral effective field theory. Specifically, the role of SU(3) symmetry breaking contact terms that arise at next-to-leading order in the employed Weinberg power counting scheme is explored. We focus on the 1S0 partial wave and on baryon-baryon channels with maximal isospin since in this case there are only two independent SU(3) symmetry breaking contact terms. At the same time, those are the channels where most of the bound states have been predicted in the past. Utilizing $pp$ phase shifts and $\Sigma^+ p$ cross section data allows us to pin down one of the SU(3) symmetry breaking contact terms and a clear indication for the decrease of attraction when going from the NN system to strangeness S=-2 is found, which rules out a bound state for $\Sigma\Sigma$ with isospin I=2. Assuming that the trend observed for S=0 to S=-2 is not reversed when going to $\Xi\Sigma$ and $\Xi\Xi$ makes also bound states in those systems rather unlikely.