Coulomb shift in ¹⁴O as the signature of the linear-chain structure

Recent years have seen many important experimental studies for the linear-chain states (linearly aligned 3α articles) in ¹⁴C and ¹⁶C. These new data motivated us to perform ananalysis and to summarize the calculated and observed properties of the linear-chain bands in carbon isotopes. In addition, it can be expected that the reduction of the Coulomb shift for the mirror system, known as the Thomas-Ehrman shift, is induced by the developed α cluster such as the linear-chain structure. In this presentation, the linear-chain states of ¹⁴C and ¹⁴O are theoretically investigated by using the antisymmetrized molecular dynamics (AMD). Especially, we focus on the suppressed energy shift of ¹⁴O(0⁺) which is considered as the new signature of the linear-chain configuration. Moreover, we also estimate the α decay width of the linear-chain states. As the result, it is found that the positive-parity linear-chain states of ¹⁴C have the molecular orbit configuration and primary decay to the 1st excited state of ¹⁰Be as well as to the ¹⁰Be(g.s.) by the particle emission.