Dr Basabendu Barman from the Department of Physics, in his research on “What KM3-230213A Event May Tell Us About Neutrino Mass and Dark Matter” examines the interesting link between very high-energy neutrinos and decaying dark matter. He suggests that the neutrinos detected by the KM3NeT experiment could come from the slow decay of a heavy dark matter particle. This discovery might help us better understand some of the universe’s mysteries.

Abstract:

Within the general $U(1)$ scenario, we demonstrate that the ultra-high-energy neutrinos recently detected by KM3NeT could originate from a decaying right-handed neutrino dark matter (DM), with a mass of 440 PeV. Considering DM production via freeze-in, we delineate the parameter space that satisfies the observed relic abundance, and also lies within the reach of multiple gravitational wave detectors. Our study provides a testable new physics scenario, enabled by multi-messenger astronomy.

Explanation in layman’s Perspective:

One of the biggest mysteries in physics today is the nature of dark matter. At the same time, experiments like KM3NeT have recently detected ultra-high-energy neutrinos, particles so energetic that they challenge our understanding of cosmic processes. KM3NeT is a large underwater neutrino telescope located deep in the Mediterranean Sea. It uses arrays of sensitive light detectors to spot the faint flashes produced when neutrinos interact with water, allowing scientists to trace some of the most extreme events in the universe. In this work, we propose a single explanation that could connect these two puzzles. We suggest that the detected neutrinos might be produced when an extremely heavy kind of dark matter made of right-handed neutrinos weighing about 440 PeV slowly decays. This type of dark matter wouldn’t have been created in the usual hot, thermal way after the Big Bang. Instead, it would have formed gradually through a process called freeze-in, where even very weak interactions can build up the right amount of dark matter over time. What makes this idea especially exciting is that the same model could also leave detectable traces in future gravitational wave experiments, giving us a way to test it from multiple directions. By combining signals from neutrinos, dark matter relic abundance, and gravitational waves, we open up a new, testable window into physics beyond the Standard Model.

Practical Implementations & Social Impact:
Although this research is fundamentally theoretical, it has clear implications for experimental strategies and future technologies. By linking dark matter, ultra–high-energy neutrinos, and gravitational waves within a single framework, the work provides concrete targets for current and upcoming detectors. Experiments like KM3NeT, IceCube-Gen2, and various planned gravitational wave observatories can use these predictions to refine their search strategies, optimize detector sensitivity, and prioritize specific energy ranges. In the longer term, insights gained from such studies can shape the design of next-generation multi-messenger observatories, which combine different cosmic signals to probe new physics. While the direct societal applications of dark matter research are not immediate, the indirect impacts are significant. Advancing our understanding of the universe stimulates technological innovation, often leading to improvements in data analysis, sensor development, and large-scale computing tools that frequently find applications in medicine, environmental monitoring, and industry.

Collaborations:
This work has been done in collaboration with Arindam Das (Institute for the Advancement of Higher Education, Hokkaido University) and Prantik Sarmah (Institute of High Energy Physics, Chinese Academy of Sciences, Beijing).