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

The Ultra-relativistic Quantum Molecular Dynamics model is employed to simulate π^-+C and π^-+W collisions at p_lab=1.7 GeV motivated by the recent HADES results. By comparing the proton and Λ 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, ^3He, ^4He, as well as ^3_ΛH and ΞN) 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_ΛH, especially in π^-+W collisions due to the stopping of the Λ 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.