Photodisintegration and Virtual State in the Complex Scaling Method

The photodisintegration cross section observed just above the neutron threshold energy in 9Be is discussed in the framework of an α + α + n three-cluster model and the complex scaling method. The observed cross sections shows a remarkable sharp peak, which has been discussed in association with photo-neutron reactions in nucleo-syntheses of chemical elements. It is discussed that the enhancement of the peak is understood by taking into account a virtual state but not a resonant state. The complex scaling method cannot reproduce an eigenvalue corresponding to the virtual pole, but provides us with a useful tool for investigation of the photodisintegration cross section.