Role of diproton correlation in two-proton-emission decay of the Be 6 nucleus

We discuss a role of diproton correlation in two-proton emission from the ground state of a proton-rich nucleus, Be6. Assuming the three-body structure of α+p+p configuration, we develop a time-dependent approach in which the two-proton emission is described as a time evolution of a three-body metastable state. With this method, the dynamics of the two-proton emission can be intuitively discussed by monitoring the time dependence of the two-particle density distribution. With a model Hamiltonian which well reproduces the experimental two-proton decay width, we show that a strongly correlated diproton emission is a dominant process in the early stage of the two-proton emission. When the diproton correlation is absent, the sequential two-proton emission competes with the diproton emission, and the decay width is underestimated. These results suggest that the two-proton emission decays provide a good opportunity to probe the diproton correlation in proton-rich nuclei beyond the proton dripline.