Collective core effects and dineutron correlations in three-body nuclei

Two-neutron halo nuclei, such as 6He, 11Li or 14Be, are known to have a marked (core + n + n) three-body character, which is reflected in breakup, transfer or knockout reactions channels in nucleon-nucleon collisions. Their Borromean nature implies that the correlation between the valence halo neutrons is key to understand their properties, and their structure is also linked to spectra of the unbound core + n systems. Among other phenomena, the role of core collective excitations may be crucial to understand exotic properties such as parity inversion or shell gap quenching in the vicinity of nuclear halos and related systems. In this contribution it is shown that dineutron correlations can be succesfully probed in proton-target knockout reactions, and that core excitation may be an important ingredient for a proper understanding of experimental observations.Two-neutron halo nuclei, such as 6He, 11Li or 14Be, are known to have a marked (core + n + n) three-body character, which is reflected in breakup, transfer or knockout reactions channels in nucleon-nucleon collisions. Their Borromean nature implies that the correlation between the valence halo neutrons is key to understand their properties, and their structure is also linked to spectra of the unbound core + n systems. Among other phenomena, the role of core collective excitations may be crucial to understand exotic properties such as parity inversion or shell gap quenching in the vicinity of nuclear halos and related systems. In this contribution it is shown that dineutron correlations can be succesfully probed in proton-target knockout reactions, and that core excitation may be an important ingredient for a proper understanding of experimental observations.