Medium effects in antikaon-induced $\Xi^-$ hyperon production on nuclei near threshold

TL;DR

This paper investigates how antikaon-induced reactions near threshold produce $ ext{Xi}^-$ hyperons in nuclei, revealing sensitivity of production cross sections and transparency ratios to the $ ext{Xi}^-$ nuclear potential, with implications for in-medium hyperon properties.

Contribution

The study provides a detailed theoretical analysis of $ ext{Xi}^-$ hyperon production near threshold, highlighting the sensitivity of observables to the $ ext{Xi}^-$ nuclear potential, guiding future experiments.

Findings

Differential and total cross sections are sensitive to the $ ext{Xi}^-$ nuclear potential at low momenta.

Transparency ratios show strong sensitivity to the $ ext{Xi}^-$ potential at subthreshold momenta.

Results suggest measurements at J-PARC can reveal in-medium properties of $ ext{Xi}^-$ hyperons.

Abstract

We study the antikaon-induced inclusive cascade $\Xi^-$ hyperon production from $^{12}$C and $^{184}$W target nuclei near threshold within a nuclear spectral function approach. The approach describes incoherent direct $\Xi^-$ hyperon production in elementary ${K^-}p \to {K^+}\Xi^-$ and ${K^-}n \to {K^0}\Xi^-$ processes as well as takes into account the influence of the scalar nuclear $K^-$, $K^+$, $K^0$, $\Xi^-$ and their Coulomb potentials on these processes. We calculate the absolute differential and total cross sections for the production of $\Xi^-$ hyperons off these nuclei at laboratory angles $\le$ 45$^{\circ}$ by $K^-$ mesons with momenta of 1.0 and 1.3 GeV/c, which are close to the threshold momentum (1.05 GeV/c) for $\Xi^-$ hyperon production on the free target nucleon at rest. We also calculate the momentum dependence of the transparency ratio for the $^{184}$W/$^{12}$C combination for $\Xi^-$ hyperons at these $K^-$ beam momenta. We show that the $\Xi^-$ differential and total (absolute and relative) production cross sections at the considered initial momenta reveal a distinct sensitivity to the variations in the scalar $\Xi^-$ nuclear potential at saturation density $\rho_0$, studied in the paper, in the low-momentum region of 0.1--0.6 GeV/c. We also demonstrate that for the subthreshold $K^-$ meson momentum of 1.0 GeV/c there is a strong sensitivity of the transparency ratio for $\Xi^-$ hyperons to the considered changes in the $\Xi^-$ nuclear potential at all outgoing $\Xi^-$ momenta as well. Therefore, the measurement of these absolute and relative observables in a dedicated experiment at the J-PARC will provide valuable information on the $\Xi^-$ in-medium properties, which will be complementary to that deduced from the study of the inclusive ($K^-$,$K^+$) reactions at incident momenta of 1.6--1.8 GeV/c in the $\Xi^-$ bound and quasi-free regions.