Shakeoff of the Vacuum Polarization in Quasimolecular Collisions of Very Heavy Ions

Abstract

The theory of direct electron-positron pair production in the collision of heavy ions is formulated in the framework of the quasimolecular model. The pair production process acquires a collective nature for $({Z}_{1}+{Z}_{2})\ensuremath{\alpha}>1$ and can be understood as the shakeoff of the strong vacuum polarization cloud formed in the quasimolecule. The total cross section is, e.g., 76 \ensuremath{\mu}b for Pb + Pb at Coulomb barrier energies.