Flavor-vacuum entanglement in boson mixing

Mixing transformations in quantum field theory are nontrivial, since they are intimately related to the unitary inequivalence between Fock spaces for fields with definite mass and fields with definite flavor. Considering the superposition of two neutral scalar (spin-0) bosonic fields, we investigate some features of the emerging condensate structure of the flavor vacuum. In particular, we quantify the flavor vacuum entanglement in terms of the von Neumann entanglement entropy of the reduced state. Furthermore, in a suitable limit, we show that the flavor vacuum has a structure akin to the thermal vacuum of thermo field dynamics, with a temperature dependent on both the mixing angle and the particle mass difference.

Automated summary

The study investigates the condensate structure of flavor vacuum resulting from the superposition of two neutral scalar bosonic fields, quantifying the flavor vacuum entanglement with the von Neumann entanglement entropy of the reduced state. It further shows that the flavor vacuum resembles the thermal vacuum of thermo field dynamics in a suitable limit, with a temperature dependent on both the mixing angle and the particle mass difference.