Hypernuclear Spectroscopy with Heavy-Ion Beams: Present Status and Perspectives

Research on the strange quark involves the study of the baryon-baryon interactions within SU(3)\(_f\). The determination of the interaction strength between the hyperons (baryon containing a s-quark) and the nucleons is crucial for the description of the equation of state of neutron stars. The HypHI (Hypernuclei with Heavy Ion) collaboration demonstrated the feasibility of the spectroscopy of hypernuclei produced in ion-induced reactions. A first experiment was performed with a \(^{6}\)Li beam bombarding a carbon target at 2 AGeV. The experimental approach was developed to measure and study hypernuclei produced in the projectile rapidity region of the nuclear collisions. Such \(\varLambda \)-hypernuclei are produced by the coalescence between a \(\varLambda \) hyperon produced in the mid-rapidity region of the participant zone and a spectator fragment. The current status of the HypHI project are reviewed: the results on \(^{3}_\varLambda \)H and \(^{4}_\varLambda \)H are presented, together with the possible signal of nn\(\varLambda \). The forthcoming experiment at the fragment separator FRS at GSI is described, aiming to improve the hypernuclear spectroscopy. The main goal is to verify the existence or not of a nn\(\varLambda \) bound state. The spectroscopy of \(^{3}_\varLambda \)H and study of its lifetime will be also pursued. The study of \(^{3}_\varLambda \)H and possibly of \(^{4}_\varLambda \)H will be used to demonstrate the feasibility of the new experimental approach of using a fragment separator for the measure of the decay fragments. Finally, further prospects within the HIAF facility on hypernuclear spectroscopy by heavy-ion reaction will be mentioned.