Could traces of superheavy charged gravitinos be detected by underground detectors?
To the point:
- Big mystery: The nature of dark matter remains unclear. Possible candidates are new types of elementary particles. The present work proposes superheavy charged gravitinos to explain dark matter. These particles differ radically from all previously proposed candidates (axions, WIMPs, etc.).
- Possible detection: A research team involving the Max Planck Institute for Gravitational Physics and the University of Warsaw shows how new underground detectors could detect these particles based on their distinctive traces.
- Interdisciplinary approach: The analysis combines two very different fields of research: elementary particle physics and the search for a fundamental theory using methods of modern quantum chemistry.
In an earlier study, Hermann Nicolai from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) at Potsdam Science Park and Krzysztof Meissner from the Faculty of Physics at the University of Warsaw had already postulated superheavy electrically charged gravitinos as possible candidates for dark matter and proposed methods to search for them in planned underground experiments. The recently published paper shows how large underground neutrino detectors could detect these particles based on their distinctive traces. In the paper, the researchers present a detailed analysis of the specific signatures that events caused by gravitinos could produce at the Jiangmen Underground Neutrino Observatory (JUNO) and in future liquid argon detectors such as the Deep Underground Neutrino Experiment (DUNE). The current analysis also sets new standards in terms of interdisciplinarity by combining two very different areas of research: elementary particle physics and the search for a fundamental theory on the one hand, and methods of modern quantum chemistry on the other. The latter were contributed to this collaboration by Adrianna Kruk and Michal Lesiuk from the Faculty of Chemistry at the University of Warsaw.
An unsolved mystery
The nature of dark matter remains one of the greatest mysteries of modern astrophysics. Numerous proposals are on the table, ranging from novel elementary particles to fundamental modifications of Einstein's theory of gravity. In particle physics, supersymmetric particles, ultralight axion-like particles, and the much heavier WIMPs (weakly interacting massive particles) are discussed as possible candidates, all of which interact only very weakly with normal matter. “Many researchers had high expectations for the results of the Large Hadron Collider experiments,” says Hermann Nicolai, Director Emeritus at the AEI, “but no new particles beyond the Standard Model were detected.” Other experiments have also failed to find any evidence of such particles in this 40-year search. Nor have proposed modifications to Einstein's theory led to satisfactory answers. However, with the possible direct detection of superheavy gravitinos in underground detectors, it may now be possible to track down dark matter with a new idea.
The proposal for a dedicated search for superheavy gravitinos is based on previous work on the unification of fundamental interactions by Nicolai and his colleague Krzysztof Meissner, which could explain in particular the fermion spectrum of the Standard Model of particle physics with three generations of quarks and leptons. In this model, superheavy gravitinos (which carry spin 3/2) would be the only new fermions beyond the Standard Model. These still hypothetical elementary particles differ significantly from all previously proposed candidates. For example, a gravitino carries fractional electric charge and, in principle, can be detected directly thanks to its interaction with normal matter. However, the search is made enormously difficult by its extremely low abundance (roughly estimated to be only one gravitino per 10,000 km3 on average), which is why there is no prospect of detection with currently available detectors. However, with the commissioning of new giant underground detectors, realistic possibilities for searching for these particles are now opening up.
The proposal for a dedicated search for superheavy gravitinos is based on previous work on the unification of fundamental interactions by Nicolai and his colleague Krzysztof Meissner, which could explain in particular the fermion spectrum of the Standard Model of particle physics with three generations of quarks and leptons. In this model, superheavy gravitinos (which carry spin 3/2) would be the only new fermions beyond the Standard Model. These still hypothetical elementary particles differ significantly from all previously proposed candidates. For example, a gravitino carries fractional electric charge and, in principle, can be detected directly thanks to its interaction with normal matter. However, the search is made enormously difficult by its extremely low abundance (roughly estimated to be only one gravitino per 10,000 km3 on average), which is why there is no prospect of detection with currently available detectors. However, with the commissioning of new giant underground detectors, realistic possibilities for searching for these particles are now opening up.
Superheavy gravitinos in a neutrino detector
“The observation method we propose for superheavy gravitinos is not based on ionization, as one might expect, but on a kind of ‘glow’. This glow comes from photons that should be generated when such particles pass through the detection fluid in large neutrino observatories,” says Hermann Nicolai, co-author of the study. “According to our calculations, this glow can last from a few microseconds to several hundred microseconds and would produce a characteristic trace through the detector for the superheavy gravitinos we postulate.”
Among all currently existing detectors, the Chinese JUNO underground observatory seems predestined for such a search. It aims to determine the properties of neutrinos more accurately than has been possible until now, to observe neutrinos from cosmic, atmospheric, and geological sources, and to search for new particles beyond the Standard Model. Neutrinos do not interact with electromagnetic fields and rarely react with matter. In order to observe any reactions at all, neutrino detectors must therefore have extremely large volumes. In the case of the JUNO detector, this means 20,000 tons of an organic, synthetic oil-like liquid, commonly used in chemical industry, with special additions, in a spherical vessel with a diameter of approximately 40 meters. The search for gravitinos could be conducted in parallel and independently of neutrino reactions. The quantum chemistry of the scintillator oil and its specific properties would play a central role in the predicted effect. JUNO is scheduled to begin measurements in the second half of 2025.
Among all currently existing detectors, the Chinese JUNO underground observatory seems predestined for such a search. It aims to determine the properties of neutrinos more accurately than has been possible until now, to observe neutrinos from cosmic, atmospheric, and geological sources, and to search for new particles beyond the Standard Model. Neutrinos do not interact with electromagnetic fields and rarely react with matter. In order to observe any reactions at all, neutrino detectors must therefore have extremely large volumes. In the case of the JUNO detector, this means 20,000 tons of an organic, synthetic oil-like liquid, commonly used in chemical industry, with special additions, in a spherical vessel with a diameter of approximately 40 meters. The search for gravitinos could be conducted in parallel and independently of neutrino reactions. The quantum chemistry of the scintillator oil and its specific properties would play a central role in the predicted effect. JUNO is scheduled to begin measurements in the second half of 2025.
Unifying the forces of nature?
“The detection of the superheavy gravitinos we predicted would also be a major step forward in the search for a unified theory,” says Hermann Nicolai. “Since gravitinos are predicted to have masses on the order of the Planck mass, their detection would be the first direct indication of physics near the Planck scale and could thus provide valuable experimental evidence for a unification of the forces of nature — evidence that does not yet exist in this form.”
Media contact:
Dr. Elke Müller
Press Officer AEI Potsdam, Scientific Coordinator
+49 331 567-7303
elke.mueller@aei.mpg.de
Scientific contact:
Prof. Dr. Dr. h.c. Hermann Nicolai
Director emeritus
Tel:+49 331 567-7355
Fax:+49 331 567-7297
hermann.nicolai@aei.mpg.de
Publications
1. Kruk, A., Lesiuk, M., Meissner, K. A., Nicolai, H.
Signatures of supermassive charged gravitinos in liquid scintillator detectors
Phys. Rev. Research 7, 033145 (2025)
Source | DOI
2. Meissner, K.A., Nicolai, H.
Standard model symmetries and K(E10
J. High Energ. Phys. 2025, 54 (2025)
Source | DOI
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