What can we learn about baryon-baryon interaction from hypernuclei ⁶_Λ H and ⁸_Λ H?

Abstract

At the LHE JINR, an original approach to hypernuclear experiments was elaborated to produce relativistic hypernuclei. The production cross sections and lifetimes, τ, of ³_Λ H and ⁴_Λ H were measured successfully. The results of recent experiments on ⁵H and ⁷H nuclei suggest that the hypernucleus ⁶_Λ H might be stable and that this may be the case even for ⁸_Λ H. The unique quality of the spectrometer SPHERE may be used to identify unambiguously the isotopes of hyperhydrogen—through their pionic decay ^A_Λ H → π ⁻ + ^AHe—including the new hypernuclei ⁶_Λ H and ⁸_Λ H with extreme values of N/Z of 4 and 6, respectively. The confirmation of the very existence of these neutron-rich hypernuclei would be a strong motivation to search for their spectra in strangeness and double-charge-exchange reactions (K ⁻_stop , π ⁺) at FINUDA or (π ⁻, K ⁺) at J-PARC. It is very probable that, similarly as in ⁴_Λ H, there is a low-lying state 1⁺ also in ⁶_Λ H and ⁸_Λ H. If their electromagnetic width (M1) is small enough, we could see two different values of τ for ⁶_Λ H and/or ⁸_Λ H. We investigate the spacings of the 1⁺ and 0⁺ states of ⁴_Λ H, ⁶_Λ H, and ⁸_Λ H. The understanding of the structure of isospin asymmetric systems plays a key role in the description of systems as diverse as neutron-rich nuclei and neutron matter.