Roles of tensor and pairing correlations on halo formation in 11Li

We studied the roles of the tensor and pairing correlations on the halo formation in Li-11 with an extended Li-9+n+n model. We first solved the ground state of Li-9 in the shell-model basis by taking 2p-2h states using the Gaussian functions with variational size parameters to take into account the tensor correlation fully. In Li-11, the tensor and pairing correlations in Li-9 are Pauli blocked by additional two neutrons, which work coherently to make the configurations containing the 0p(1/2)-state pushed up and close to those containing the 1s(1/2)-state. Hence, the pairing interaction works efficiently to mix the two configurations by equal amount and develop the halo structure in Li-11. For Li-10, the inversion phenomenon of s- and p-states is reproduced in the same framework. Our model furthermore explains the recently observed Coulomb breakup strength and charge radius for Li-11.