Darkish Matter stays one of many greatest mysteries in elementary physics. Many theoretical proposals (axions, WIMPs) and 40 years of intensive experimental search failed to supply any rationalization of the character of Darkish Matter. A number of years in the past, in a idea unifying particle physics and gravity, new, radically completely different Darkish Matter candidates have been proposed, superheavy charged gravitinos. Very latest paper in Bodily Overview Analysis by scientists from the College of Warsaw and Max Planck Institute for Gravitational Physics, exhibits how new underground detectors, specifically JUNO detector beginning quickly to take knowledge, though designed for neutrino physics, are additionally extraordinarily nicely suited to finally detect charged Darkish Matter gravitinos. The simulations combining two fields, elementary particle physics and really superior quantum chemistry, present that the gravitino sign within the detector needs to be distinctive and unambiguous.
In 1981 Murray Gell-Mann, Nobel Prize laureate for the introduction of quarks as elementary constituents of matter, observed the intriguing indisputable fact that the particles of the Customary Mannequin, quarks and leptons, are contained in a idea formulated purely mathematically 2 years earlier, N=8 supergravity, distinguished by its maximal symmetry. N=8 supergravity accommodates, moreover Customary Mannequin matter particles of spin 1/2, additionally gravitational half: graviton (of spin 2) and eight gravitinos of spin 3/2. If the Customary Mannequin is certainly associated to N=8 supergravity, the relation might probably level to a path to unravel essentially the most tough downside of elementary theoretical physics — unifying gravity with particle physics. N=8 supergravity within the spin ½ sector accommodates precisely 6 quarks (u,d,c,s,t,b) and 6 leptons (electron, muon, taon and neutrinos) and forbids the presence of another matter particles. After 40 years of intensive accelerator analysis failing to find any new matter particles the N=8 supergravity matter content material is just not solely per our data however stays the one identified theoretical rationalization of the variety of quarks and leptons within the Customary Mannequin! Nevertheless, direct connection of N=8 supergravity with the Customary Mannequin had a number of drawbacks, the primary one being that the electrical fees of quarks and leptons have been shifted by ±1/6 with respect to the identified values, for instance electron had cost -5/6 as a substitute of -1. A number of years in the past Krzysztof Meissner from the School of Physics on the College of Warsaw, Poland and Hermann Nicolai from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI), Potsdam, Germany returned to the Gell-Mann’s thought and have been in a position to transcend N=8 supergravity and modify the unique proposal acquiring right electrical fees of the Customary Mannequin matter particles. The modification may be very far reaching pointing to an infinite symmetry Okay(E10), little identified mathematically and changing the standard symmetries of the Customary Mannequin.
One of many shocking outcomes of the modification, described in papers in Bodily Overview Letters and Bodily Overview, is the truth that the gravitinos, presumably of the extraordinarily giant mass near the Planck scale i.e. billion billion proton plenty, are electrically charged: 6 of them have cost ±1/3 and a pair of of them ±2/3. The gravitinos, though they’re extremally large, can not decay since there are not any particles they might decay into. Meissner and Nicolai proposed subsequently that 2 gravitinos of cost ±2/3 (the opposite 6 have a lot decrease abundance) may very well be Darkish Matter particles of very completely different sort than something proposed to this point. Specifically, the broadly advertized normal candidates, both extraordinarily gentle like axions or intermediate (proton) mass like WIMPs (weakly interacting large particles) have been electrically impartial, in compatibility with the title ‘Darkish Matter’. Nevertheless, after greater than 40 years of intensive search by many alternative strategies and units no new particles past the Customary Mannequin have been detected.
Nevertheless, gravitinos current a brand new different. Regardless that they’re electrically charged, they are often Darkish Matter candidates as a result of being so large they’re extraordinarily uncommon and subsequently observationally ‘don’t shine on the sky’ and keep away from the very tight constraints on the cost of Darkish Matter constituents. Furthermore, the electrical cost of gravitinos advised a very completely different method of attempting to show their existence. The unique paper in 2024 in Eur. Phys. J. by Meissner and Nicolai identified that neutrino detectors, based mostly on scintillators completely different from water, may very well be appropriate for the detection of Darkish Matter gravitinos. Nevertheless, the search is made enormously tough by their excessive rarity (presumably just one gravitino per 10,000 km3 within the Photo voltaic System), which is why there is no such thing as a prospect of detection with presently out there detectors. Nevertheless, new big, oil or liquid argon underground detectors, are both constructed or deliberate and practical prospects for trying to find these particles are actually opening up.
Amongst all detectors, the Chinese language Jiangmen Underground Neutrino Observatory (JUNO) now underneath development, appears predestined for such a search. It goals to find out the properties of neutrinos (truly antineutrinos) however since neutrinos work together extraordinarily weakly with matter the detectors should have very giant volumes. Within the case of the JUNO detector, this implies 20,000 tons of an natural, artificial oil-like liquid, generally utilized in chemical trade, with particular additions, in a spherical vessel with a diameter of roughly 40 meters with greater than 17 thousand photomultipliers across the sphere. JUNO is scheduled to start measurements within the second half of 2025.
The lately revealed paper in Bodily Overview Analysis by Meissner and Nicolai, with collaborators Adrianna Kruk and Michal Lesiuk from the School of Chemistry on the College of Warsaw, presents an in depth evaluation of the precise signatures that occasions attributable to gravitinos may produce at JUNO and in future liquid argon detectors such because the Deep Underground Neutrino Experiment (DUNE) in america. The paper describes not solely the theoretical background each on the physics and chemistry sides but additionally very detailed simulation of the doable signatures as a perform of the speed and monitor of a gravitino touring via the oil vessel. It required very superior data of quantum chemistry and intensive CPU-time consuming calculations. The simulations needed to take note of many doable backgrounds – decay of radioactive C14 current within the oil, darkish depend price and effectivity of photomultipliers, absorption of photons in oil and so forth. The simulations present that, with the suitable software program, passage of a gravitino via the detector will go away a novel sign unimaginable to be wrongly recognized with a passage of any of the presently identified particles. The evaluation units new requirements when it comes to interdisciplinarity by combining two completely different areas of analysis: theoretical and experimental elementary particle physics on one hand and really superior strategies of recent quantum chemistry on the opposite.
The detection of the superheavy gravitinos could be a serious step ahead within the seek for a unified idea of gravity and particles. Since gravitinos are predicted to have plenty on the order of the Planck mass, their detection could be the primary direct indication of physics close to the Planck scale and will thus present useful experimental proof for a unification of all forces of nature.
