Nuclear Structure and Dynamics

Understanding the phenomenon of parity inversion in beryllium-11

Understanding the phenomenon of parity inversion in beryllium-11: It has been known since 1960s that the spectrum of beryllium-11 (11Be) has peculiar features, namely, its weakly bound ground state has positive parity contrary to the standard shell model picture. Yet, a first-principles explanation of this phenomenon has been lacking. As reported in Physical Review Letters (2016), TRIUMF nuclear theorists investigated this nucleus ab initio and demonstrated that the inclusion of continuum effects is crucial for a description of the 11Be system. The results showed that the spectrum is extremely sensitive to the details of the nuclear two- and three-nucleon interactions and constitutes an important benchmark for future forces. In particular, the parity inversion of the bound states could be achieved only by a nuclear force that provides accurate predictions of nuclear radii and matter saturation properties.