Spontaneous decay of supercritical vacuum in e+e− pair during the passage of a magnetic monopole close to a high-Z atom

Summary  We investigate if a magnetic monopole, passing close to a sufficiently high-Z atom, may ionize it and originate a supercritical vacuum, this being followed by a spontaneous emission of a positron during the vacuum decay. Despite the lack of knowledge of the monopole structure, we solve the relativistic equations describing the system monopole plus atom by resorting to the numerical results already obtained in ion-ion collisions by Greiner and collaborators. We find that the process of e+e− formation occurs for the atomic numbersZ greater than 74.