Instability of infinite nuclear matter in the relativistic Hartree approximation

We demonstrate that within the relativistic Hartree approximation to quantum hadrodynamics, infinite nuclear matter is unstable for some combinations of the vector and scalar meson masses. In this region of instability, the Hartree ground state of nuclear matter is characterized by a periodic spatial variation of the baryon density that may be interpreted as alpha-particle clustering. The standard values of the meson masses are in a region in which uniform nuclear matter is stable; however, for finite nuclei the presence of the nuclear surface can induce small scale oscillations in the nuclear interior that are related to the periodic instability.