Superheavy Charged Gravitinos Proposed as Novel Dark Matter Candidates

In a study published on August 13, 2025, in Physical Review Research, physicists from the University of Warsaw and the Max Planck Institute for Gravitational Physics have proposed superheavy charged gravitinos as novel dark matter candidates. These particles, with masses near the Planck scale and electric charges of ±2/3, challenge traditional notions of dark matter and open new avenues for detection using advanced underground observatories like China's Jiangmen Underground Neutrino Observatory (JUNO).

Dark matter constitutes approximately 27% of the universe's mass-energy content, yet its nature remains one of the most profound mysteries in physics. Gravitinos are hypothetical particles predicted by supersymmetry, a theoretical framework that extends the Standard Model of particle physics. In this study, modifications to N=8 supergravity theory predict superheavy charged gravitinos with masses near the Planck scale (approximately 1.22 × 10¹⁹ GeV/c²) and electric charges of ±2/3. Despite their charge, their extreme mass results in a low cosmic abundance, rendering them effectively "dark."

The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose neutrino experiment located 700 meters underground in Kaiping, Jiangmen City, Guangdong Province, China. The project was proposed in 2008 and approved in 2013. JUNO features a 20,000-ton liquid scintillator detector designed to determine the neutrino mass hierarchy and precisely measure oscillation parameters by detecting reactor neutrinos from the Yangjiang and Taishan Nuclear Power Plants. The central detector consists of an acrylic sphere with an inner diameter of 35.4 meters, filled with liquid scintillator. Surrounding this sphere are 18,000 20-inch photomultiplier tubes (PMTs) and 36,000 3-inch PMTs, achieving a photocathode coverage of over 75%. The entire setup is submerged in a pure water pool, which acts as an active cosmic ray veto. JUNO began data collection on August 26, 2025.

Simulations indicate that a gravitino passing through JUNO's liquid scintillator would produce a unique and unambiguous signal, distinct from known particles. This distinct signature arises from the specific interactions of the charged gravitinos with the scintillator material, leading to detectable light emissions captured by JUNO's sensitive photomultiplier tubes.

The proposal of superheavy charged gravitinos as dark matter candidates bridges the gap between particle physics and cosmology, offering a testable hypothesis for dark matter detection. If JUNO or similar detectors observe the predicted signals, it would not only confirm the existence of these particles but also provide empirical evidence supporting modifications to supergravity theories.

The successful detection of such particles would have profound implications for our understanding of the universe's composition and the fundamental forces governing it. It could pave the way for new physics beyond the Standard Model and offer insights into the unification of gravity with other fundamental interactions.

The study by researchers from the University of Warsaw and the Max Planck Institute for Gravitational Physics presents a compelling case for superheavy charged gravitinos as dark matter candidates. With advanced detectors like JUNO now operational, the scientific community stands on the brink of potentially groundbreaking discoveries that could unravel the mysteries of dark matter and the fundamental structure of the universe.