Many-body theories for negative kinetic energy systems

In the author’s previous works, it is derived from the Dirac equation that particles can have negative kinetic energy (NKE) solutions, and they should be treated on an equal footing as the positive kinetic energy (PKE) solutions. More than one NKE particles can make up a stable system by means of interactions between them and such a system has necessarily negative temperature. Thus, many-body theories for NKE systems are desirable. In this work, the many-body theories for NKE systems are presented. They are Thomas‐Fermi method, Hohenberg‐Kohn theorem, Khon‐Sham self-consistent equations, and Hartree‐Fock self-consistent equations. They are established imitating the theories for PKE systems. In each theory, the formalism of both zero temperature and finite negative temperature is given. In order to verify that tunneling electrons are of NKE and real momentum, an experiment scenario is suggested that lets PKE electrons collide with tunneling electrons.