Production of nuclei and hypernuclei in pion-induced reactions near threshold energies

TL;DR

This study uses a transport model to simulate pion-induced nuclear reactions near threshold energies, predicting hypernuclei production and suggesting experimental feasibility for observing double strange hypernuclei.

Contribution

It introduces predictions for hypernuclei production in pion-induced reactions using a coalescence mechanism and compares model results with recent experimental data.

Findings

Good agreement between data and model when cluster formation is included

Substantial production of ${}^{3}_ ext{Λ}$H in pion-W collisions

Potential to produce and study double strange hypernuclei

Abstract

The Ultra-relativistic Quantum Molecular Dynamics model is employed to simulate $\pi^-+\mathrm{C}$ and $\pi^-+\mathrm{W}$ collisions at p$_\mathrm{lab}=1.7$ GeV motivated by the recent HADES results. By comparing the proton and $\Lambda$ transverse momentum spectra, it was observed that the data and transport model calculation show a good agreement, if cluster formation is included to obtain the free proton spectra. Predictions of light cluster ($d$, $t$, $^3$He, $^4$He, as well as ${}^{3}_\Lambda$H and $\Xi$N) multiplicities and spectra are made using a coalescence mechanism. The resulting multiplicities suggest that the pion beam experiment can produce a substantial amount of ${}^{3}_\Lambda$H, especially in $\pi^-+\mathrm{W}$ collisions due to the stopping of the $\Lambda$ inside the large tungsten nucleus. The findings are supplemented by a statistical multi-fragmentation analysis suggesting that even larger hyper-fragments are produced copiously. It is suggested that even double strange hypernuclei are in reach and might be studied in more detail using a slightly higher pion beam momentum.