K$^-$ absorption on two nucleons and ppK$^-$ bound state search in the $\Sigma^0$p final state

TL;DR

This study measures K$^-$ absorption on two nucleons and searches for the ppK$^-$ bound state in the $ ext{Σ}^0$p final state, providing the first exclusive measurement and quantifying the bound state's possible contribution.

Contribution

It presents the first exclusive measurement of two nucleon absorption processes and assesses the potential existence of the ppK$^-$ bound state in the $ ext{Σ}^0$p final state.

Findings

Two nucleon absorption accounts for 12% of all processes.

A possible ppK$^-$ bound state yield is observed but with low statistical significance.

The study provides new quantitative insights into K$^-$ absorption mechanisms.

Abstract

We report the measurement of K$^-$ absorption processes in the $\Sigma^0$p final state and the first exclusive measurement of the two nucleon absorption (2NA) with the KLOE detector. The 2NA process without further interactions is found to be 12\% of the sum of all other contributing processes, including absorption on three and more nucleons or 2NA followed by final state interactions with the residual nucleons. We also determine the possible contribution of the ppK$^-$ bound state to the $\Sigma^0$p final state. A yield of ppK$^- /\mathrm{K^-_{stop}}$ is found to be $(0.044 \pm 0.009\, stat ^{+ 0.004} _{- 0.005} \,syst) \cdot 10^{-2}$ but its statistical significance based on an F-test is only 1$\sigma$.