Darkish Matter stays one of many largest mysteries in elementary physics. Many theoretical proposals (axions, WIMPs) and 40 years of intensive experimental search failed to offer any rationalization of the character of Darkish Matter. A number of years in the past, in a concept unifying particle physics and gravity, new, radically totally different Darkish Matter candidates have been proposed, superheavy charged gravitinos. Very latest paper in Bodily Assessment Analysis by scientists from the College of Warsaw and Max Planck Institute for Gravitational Physics, reveals how new underground detectors, particularly JUNO detector beginning quickly to take knowledge, despite the fact that designed for neutrino physics, are additionally extraordinarily properly 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 ought to be distinctive and unambiguous.
In 1981 Murray Gell-Mann, Nobel Prize laureate for the introduction of quarks as elementary constituents of matter, seen the intriguing indisputable fact that the particles of the Customary Mannequin, quarks and leptons, are contained in a concept formulated purely mathematically 2 years earlier, N=8 supergravity, distinguished by its maximal symmetry. N=8 supergravity comprises, in addition to 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 could presumably level to a path to unravel essentially the most troublesome downside of elementary theoretical physics — unifying gravity with particle physics. N=8 supergravity within the spin ½ sector comprises precisely 6 quarks (u,d,c,s,t,b) and 6 leptons (electron, muon, taon and neutrinos) and forbids the presence of every other matter particles. After 40 years of intensive accelerator analysis failing to find any new matter particles the N=8 supergravity matter content material shouldn’t be solely in line with our data however stays the one recognized 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 recognized 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 could be very far reaching pointing to an infinite symmetry Okay(E10), little recognized mathematically and changing the same old symmetries of the Customary Mannequin.
One of many shocking outcomes of the modification, described in papers in Bodily Assessment Letters and Bodily Assessment, is the truth that the gravitinos, presumably of the extraordinarily massive mass near the Planck scale i.e. billion billion proton lots, are electrically charged: 6 of them have cost ±1/3 and a couple of of them ±2/3. The gravitinos, despite the fact that they’re extremally huge, can not decay since there are not any particles they may decay into. Meissner and Nicolai proposed subsequently that 2 gravitinos of cost ±2/3 (the opposite 6 have a lot decrease abundance) could possibly be Darkish Matter particles of very totally different variety than something proposed up to now. Particularly, the broadly advertized ordinary candidates, both extraordinarily gentle like axions or intermediate (proton) mass like WIMPs (weakly interacting huge 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. Though they’re electrically charged, they are often Darkish Matter candidates as a result of being so huge 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 steered a totally totally different means of attempting to show their existence. The unique paper in 2024 in Eur. Phys. J. by Meissner and Nicolai identified that neutrino detectors, primarily based on scintillators totally different from water, could possibly be appropriate for the detection of Darkish Matter gravitinos. Nevertheless, the search is made enormously troublesome by their excessive rarity (presumably just one gravitino per 10,000 km3 within the Photo voltaic System), which is why there isn’t any prospect of detection with at present out there detectors. Nevertheless, new big, oil or liquid argon underground detectors, are both constructed or deliberate and life like potentialities for looking for these particles at the moment are opening up.
Amongst all detectors, the Chinese language Jiangmen Underground Neutrino Observatory (JUNO) now underneath building, 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 massive 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 not too long ago printed paper in Bodily Assessment 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 particular signatures that occasions brought on by gravitinos might produce at JUNO and in future liquid argon detectors such because the Deep Underground Neutrino Experiment (DUNE) in the USA. The paper describes not solely the theoretical background each on the physics and chemistry sides but in addition very detailed simulation of the potential signatures as a perform of the speed and monitor of a gravitino touring by the oil vessel. It required very superior data of quantum chemistry and intensive CPU-time consuming calculations. The simulations needed to have in mind many potential backgrounds – decay of radioactive C14 current within the oil, darkish depend price and effectivity of photomultipliers, absorption of photons in oil and many others. The simulations present that, with the suitable software program, passage of a gravitino by the detector will go away a novel sign unimaginable to be wrongly recognized with a passage of any of the presently recognized particles. The evaluation units new requirements by way of interdisciplinarity by combining two totally different areas of analysis: theoretical and experimental elementary particle physics on one hand and really superior strategies of contemporary quantum chemistry on the opposite.
The detection of the superheavy gravitinos can be a significant step ahead within the seek for a unified concept of gravity and particles. Since gravitinos are predicted to have lots on the order of the Planck mass, their detection can be the primary direct indication of physics close to the Planck scale and will thus present helpful experimental proof for a unification of all forces of nature.
