α-Particle Condensation in ~(16)O Studied with a Full Four-Body Orthogonality Condition Model Calculation

摘要

To explore the four-α-particle condensate state in ~(16)O, we solve a full four-body equation of motion based on the four-a-particle orthogonality condition model in a large four-a-particle model space spanned by Gaussian basis functions. A full spectrum up to the 0_6~+ state is reproduced consistently with the lowest six 0~+ states of the experimental spectrum. The 0_6~+ state is obtained at about 2 MeV above the four-a-particle breakup threshold and has a dilute density structure, with a radius of about 5 fm. The state has an appreciably large a condensate fraction of 61%, and a large component of α + ~(12)C(0_2~+) configuration, both features being reliable evidence for this state to be of four-a-particle condensate nature.