Five-body resonances of 8C using the complex scaling method

概要

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We study the resonance spectroscopy of the proton-rich nucleus C-8 in the alpha + p + p + p + p cluster model. Many-body resonances are treated on the correct boundary condition as the Gamow states using the complex scaling method. We obtain the ground state of 8C as a five-body resonance for the first time, which has dominantly the subclosed (p(3/2))(4) configuration and agrees with the recent experiment for energy and decay width. We predict the second 0(+) state with the excitation energy of 5.6 MeV, which corresponds to the 2p2h state from the ground state. We evaluate the occupation numbers of four valence-protons in the C-8 states and also the J(pi) distribution of proton-pair numbers of the two 0(+) states of C-8. The ground state involves a large amount of the 2(+) proton-pair fraction, while the excited 0(2)(+) state almost consists of two of the 0(+) proton pairs, which can be understood from the (p(3/2))(2)(p(1/2))(2) configuration. We also discuss the mirror symmetry between C-8 and He-8 with an alpha+four nucleon picture. It is found that the 0(+) states retain the mirror symmetry well for the configuration properties of two nuclei.