Quantum Approach to Neutron Stars Leading to Configurations With Local Anisotropy and Mass Above the Oppenheimer-Volkoff Limit

The theory of stars consisting of non-interacting neutrons at zero Kelvin isrevisited starting from a quantum formulation. The Dirac equation is solvedin a curved space-time with spherical symmetry and N single-particle quantumstates are filled with N neutrons in such a way that the mass of the star isa minimum constrained by Einstein's equations of general relativity. Thisrule leads to quantum ground states with local isotropy (i.e. isotropicpressure) for masses below the Oppenheimer-Volkoff limit, but quantum groundstates with local anisotropy above it. The calculations suggest that thereare stable neutron stars with mass well above the currently accepted limit.