Quantum Decoherence of Neutrino Mass States Due to Neutrino Interaction with an External Environment

We derive the neutrino evolution equation, taking into account the process of quantum decoherence due to their interaction with electrons. The interaction is described by the Hamiltonian $$H_{I}=\bar{J}^{\mu}j_{\mu}$$ , where $$\bar{J}^{\mu}$$ is the current of electrons and $$j_{\mu}$$ is the neutrino current. The derived evolution equation allow to analyze the evolution of neutrino states taking into account neutrino nonforward scattering on electrons.