Excited halo nuclear state and long range interaction in nuclear reactions

Based on a three-body formulation of a nuclear reaction, we show that anew type of long-range interaction can exist in the imaginary part of the effective potential for nuclear reactions if the final-state nucleus has an excited neutron-core halo state. The existence of such a long-range interaction can lead to an enhancement of the nuclear cross section. Comparison of the new long-range effective interaction with other previously known ones is given.