The vertex constant for the virtual decay of a nucleus into two charged particles within the effective range theory

Abstract

Explicit expressions for the virtual a → b + c decay vertex constant (or the asymptotic normalization factor) for charged particles b and c are obtained for the first time using the effective range function K(k2) for the standard effective range expansion and for the case where K(k2) has a pole. The bound and resonant states of the 2He nucleus and the resonant states of the 2He and 8Be nuclei are considered as physical examples. A trajectory in the complex momentum plane is constructed for the transition from the resonant state to the virtual state while the Coulomb interaction gradually decreases.