Researchers have been able to infer the existence of Dark Matter (DM) only from the gravitational effect it seems to have on visible matter. DM seems to outweigh visible matter roughly six to one, making up about 27% of the universe. Here's a sobering fact: The matter we know and that makes up all stars and galaxies only accounts for 5% of the content of universe! But what is DM? [1]. Many experiments to detect and study Dark Matter Particles (DMPs) directly are being actively undertaken, but none have yet succeeded. Indirect detection experiments search for the products of the self-annihilation or decay of DMPs in outer space [2].In this paper, we discuss the main ideas of the Hypersphere World-Universe Model (WUM) and introduce an additional new DMP "XION" (boson) with the rest energy 10.6 μeV that is an analog of Axion. On June 28, 2023, it was announced the existence of Cosmic Gravitational Background. In frames of WUM, we give an explanation of this discovery based on the analysis of "Gravitoplasma" composed of objects with Planck mass, which were created as the result of Weak Interaction between XIONs and other particles in the Medium.