The gravitino, a theoretical particle central to supersymmetry (SUSY) theory, is being explored as a potential key to understanding dark matter and the universe's origins. As the supersymmetric partner to the graviton, the hypothetical carrier of gravity, the gravitino has a spin of 3/2 and interacts minimally with ordinary matter, making it notoriously difficult to detect.
Physicists propose that the gravitino could be a prime candidate for dark matter, the invisible substance comprising approximately 27% of the universe's mass. Its theoretical properties align with those expected of a dark matter particle: weak interaction and sufficient mass to influence cosmic structure formation. Research suggests that the gravitino mass could be in the range of several GeV to TeV. Recent research has also introduced the concept of supermassive charged gravitinos as a novel dark matter candidate, potentially detectable by advanced underground neutrino detectors like the Jiangmen Underground Neutrino Observatory (JUNO).
The validation of the gravitino's existence could bridge the gap between particle physics and cosmology, potentially leading to a quantum theory of gravity. However, detecting the gravitino presents immense challenges. Despite efforts at particle accelerators like the Large Hadron Collider (LHC), direct detection has not yet been achieved. Optimism persists, however, with future dark matter detectors and precision cosmology experiments offering hope for indirect evidence.
Experimental efforts are underway, including the Jovian-1 satellite, developed by researchers at the University of Southampton. This satellite-based experiment aims to conduct microgravity experiments to detect dark matter interactions by measuring minute forces on levitating graphite sheets using lasers. The Jovian-1 is slated for a low Earth orbit launch, where it will conduct tests for two years. Additionally, the Euclid satellite, launched in July 2024, is mapping the distribution of galaxies to shed light on dark energy and dark matter, potentially offering indirect clues in the search for particles like the gravitino.