Regularized Entanglement Entropy of Electron-Positron Scattering with a Witness Photon

Regularized quantum information metrics are calculated for the scattering process $e^-e^+ \rightarrow \gamma,Z\rightarrow \mu^-\mu^+$ that has a witness photon entangled with the initial electron-positron state. Unitarity implies the correct regularization of divergences that appear in both the final density matrix and von Neumann entanglement entropies. The entropies are found to quantify uncertainty or randomness. The variation of information, entanglement entropy, and correlation between the muon's and witness photon's helicities are found to convey equivalent information. The magnitude of the muon's expected helicity rises (falls) as the helicity entropy falls (rises). Area, or the scattering cross section, is a source of entropy for the muon's helicity entropy and momentum entropy. The muon's differential angular entropy distribution is similar to the differential angular cross section distribution, capturing the forward-backward asymmetry at high center of mass energies.