Solving Two Puzzles in One Go: Quintessence from a Decaying Dark Matter

The mystery of the Dark energy is not just its smallness. The extreme fine tuning of its density in the Early Universe such that it permits galaxy formation before creating a new inflationary epoch is its other unexplained aspect. Here we propose a model based on the very slow decay of a Super Heavy Dark Matter (SDM), presumed candidate for the origin of the Ultra High Energy Cosmic Rays (UHECRs). A small part of the remnants energy is in the form of a scalar field which decoheres and behaves like a quintessence field. This model does not need a special form for the potential and a simple ${\varphi }^4$ theory or an axion like scalar is enough. The equation of state of the Dark Energy becomes very close to a cosmological constant and is very well consistent with observations.