A brand new mannequin for darkish matter


Jan 24, 2023 (Nanowerk Information) Darkish matter stays one of many best mysteries of contemporary physics. It’s clear that it should exist, as a result of with out darkish matter, for instance, the movement of galaxies can’t be defined. However it has by no means been doable to detect darkish matter immediately in an experiment. Presently, there are a lot of proposals for brand spanking new experiments: They purpose to detect darkish matter immediately through its scattering from the constituents of the atomic nuclei of a detection medium, i.e. protons and neutrons. A group of authors together with Gilly Elor, a postdoctoral researcher on the PRISMA+ Cluster of Excellence at Johannes Gutenberg College-Mainz, Germany, and Robert McGehee and Aaron Pierce of the College of Michigan in Ann Arbor, USA, has now proposed a brand new candidate for darkish matter – and named it HYPER, for “HighlY Interactive ParticlE Relics.” The twist: Within the HYPER mannequin, a while after the formation of darkish matter within the early universe, the power of its interplay with regular matter will increase abruptly – which on the one hand makes it probably detectable in the present day and on the identical time can clarify the abundance of darkish matter. The researchers now current the HYPER Darkish Matter mannequin and the part transition it comprises for the primary time within the journal Bodily Evaluate Letters (“Maximizing Direct Detection with Extremely Interactive Particle Relic Darkish Matter”).The HYPER model covers almost the complete parameter range of planned experiments for the direct search for dark matterThe HYPER mannequin covers nearly the whole parameter vary of deliberate experiments for the direct seek for darkish matter. (Picture: Gilly Elor) (click on on picture to enlarge)

The brand new range at midnight matter sector

After the seek for heavy darkish matter particles, so-called WIMPs, has up to now not led to success, the analysis group is in search of different darkish matter particles, particularly lighter ones. On the identical time one generically expects part transitions at midnight sector, in spite of everything there are a number of within the seen sector. However earlier research have tended to neglect them. “There has not been a constant darkish matter mannequin for the mass vary that some deliberate experiments hope to entry,” says Gilly Elor. “Nonetheless, our HYPER mannequin illustrates {that a} part transition can really assist make the darkish matter extra simply detectable.” The problem for an appropriate mannequin: if darkish matter interacts too strongly with regular matter, its (exactly recognized) quantity fashioned within the early universe can be too small, contradicting astrophysical observations. Nonetheless, whether it is produced in simply the correct amount, the interplay would conversely be too weak to detect darkish matter in present-day experiments. “Our central thought, which underlies the HYPER mannequin, is that the interplay modifications abruptly as soon as. So we will have the very best of each worlds: the correct amount of darkish matter and a big interplay so we’d detect it,” Robert McGehee explains. And that is how the researchers envision it: In particle physics, an interplay is normally mediated by a selected particle, a so-called mediator – and so is the interplay of darkish matter with regular matter. Each the formation of darkish matter and its detection perform through this mediator, with the power of the interplay relying on its mass: The bigger the mass, the weaker the interplay. The mediator should first be heavy sufficient in order that the right amount of darkish matter is fashioned and later mild sufficient in order that darkish matter is detectable in any respect. The answer: there was a part transition after the formation of darkish matter, throughout which the mass of the mediator all of a sudden decreased. “Thus, on the one hand, the quantity of darkish matter is stored fixed, and then again, the interplay is boosted or strengthened in such a approach that darkish matter must be immediately detectable,” Aaron Pierce reviews.

New mannequin covers nearly the total parameter vary of deliberate experiments

Much more: “The HYPER mannequin of darkish matter is ready to cowl nearly all the vary that the brand new experiments make accessible,” enhances Gilly Elor. Particularly, the analysis group first thought-about the utmost cross part of the mediator-mediated interplay with the protons and neutrons of an atomic nucleus to be per astrophysical observations and sure particle-physics decays. The subsequent step was to contemplate whether or not there was a mannequin for darkish matter that exhibited this interplay. “And right here we got here up with the thought of the part transition,” the authors describe within the present article. “We calculated the quantity of darkish matter that exists within the universe after which simulated the part transition in our calculations.” There are an awesome many constraints to contemplate, akin to a continuing quantity of darkish matter. “Right here we’ve got to systematically examine and embody very many situations, for instance asking the query whether or not it’s actually sure that our mediator doesn’t all of a sudden result in the formation of recent darkish matter, which after all should not be”, says Gilly Elor. “However in the long run, we verified that our HYPER mannequin works!”


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