What can we learn about baryon-baryon interaction from hypernuclei Λ 6 H and Λ 8 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 Λ 3 H and Λ 4 H were measured successfully. The results of recent experiments on 5H and 7H nuclei suggest that the hypernucleus Λ 6 H might be stable and that this may be the case even for Λ 8 H. The unique quality of the spectrometer SPHERE may be used to identify unambiguously the isotopes of hyperhydrogen—through their pionic decay Λ H → π − + A He—including the new hypernuclei Λ 6 H and Λ 8 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 Λ 4 H, there is a low-lying state 1+ also in Λ 6 H and Λ 8 H. If their electromagnetic width (M1) is small enough, we could see two different values of τ for Λ 6 H and/or Λ 8 H. We investigate the spacings of the 1+ and 0+ states of Λ 4 H, Λ 6 H, and Λ 8 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.