Cross section of the $pp\to K^+\Sigma^+n$ reaction close to threshold

TL;DR

This study measures the production cross section of the $pp\to K^+\Sigma^+n$ reaction near threshold, revealing a smaller cross section than previous data and supporting a phase space dependence across energies.

Contribution

First measurement of the $pp\to K^+\Sigma^+n$ cross section near threshold, providing new insights into hyperon production mechanisms.

Findings

The $\Sigma^+n$ cross section is smaller than previous measurements.

Data are consistent with phase space dependence across energies.

Hyperon-nucleon invariant mass spectra were decomposed into three parts.

Abstract

We have measured inclusive data on $K^+$-meson production in $pp$ collisions at COSY J\"ulich close to the hyperon production threshold and determined the hyperon-nucleon invariant mass spectra. The spectra were decomposed into three parts: $\Lambda p$, $\Sigma^0p$ and $\Sigma^+n$. The cross section for the $\Sigma^+n$ channel was found to be much smaller than a previous measurement in that excess energy region. The data together with previous results at higher energies are compatible with a phase space dependence.