Hypernuclei

Research Group Alexandre Obertelli

Exotic Nuclear Matter

Hypernuclei

Hyperons, baryons with at least one strange quark, are expected to be an important building block of high-density matter such as neutron stars. The Λ particle with quark constituents usd is the lightest hyperon, with mass 1115 MeV/c^2, zero charge, isospin T = 0 and strangeness S = -1, a new quantum number not contained normally inside nuclei. The Λ hyperon is unstable and decays via the weak interaction with a lifetime of 263(2) ps. Since strangeness is conserved in the strong interaction, the Λ particle can stay in contact with nucleons inside nuclei and form short-lived hypernuclei. Hypernuclei offers new opportunities to learn about the Λnn three-body interaction and ΛN interactions in general. Hypernuclei studies shed a new light on the world of traditional nuclei.

HYDRA-TPC prototype inside the GLAD dipole magnet at R3B, GSI/FAIR

Few hypernuclei have been synthesised and studies so far. We are interested in understanding their production from heavy-ion collisions as first pioneered by the HyPHI project at GSI, in view of developing a new physics program at FAIR within the R3B collaboration. This implies the design and development of a new setup for hypernuclei studies. With the HYPER project, we also investigate novel methods towards the production and the high-resolution spectroscopy of hypernuclei. HYPER pioneers a new production mechanism of hypernuclei from antimatter at the Antimatter Factory of CERN. The measured precision ground-state properties and spectroscopy of single-Λ hypernuclei along isotopic chains, from neutron deficient to neutron rich, will give access to the isospin properties of the many-body interactions involving Λ-hyperons, and thus to the role of strangeness in the nuclear equation of state and in neutron stars.