dark matterthe elusive matter that makes up the majority of the mass in the universe, may consist of massive particles called gravitons that first came into existence in the first instant after the great explosion.
A new theory suggests that these virtual particles may be cosmic refugees from extra dimensions.
The researchers’ calculations indicate that these particles could have formed in the right quantities to explain dark matterwhich can only be “seen” by their gravity on ordinary matter.
“Massive gravitons are produced by collisions of ordinary particles in the early universe.
This process is thought to be too rare for massive gravitons to be candidates for dark matter,” study co-author Giacomo Cacciaglia, a physicist at the University of Lyon in France, told Live Science.
But in a new study published in February in the journal Physical Review LettersCacciapaglia, along with Korea University physicists Haiying Cai and Seung J. Lee, found that enough of these gravitons were synthesized in the early universe to account for all the dark matter we currently discover in the universe.
The study found that gravitons, if present, would have a mass of less than 1 megaelectronvolt (MeV), so no more than twice the mass of an electron.
This mass level is much lower than the scale at which Higgs boson It generates mass of ordinary matter – which is essential for the model to produce enough of it to explain all the dark matter in the universe. (For comparison, the lightest known particle is neutrinoweighs less than 2 MeV, while the proton weighs about 940 MeV, according to National Institute of Standards and Technology.)
The team found these hypothetical gravitons while searching for evidence of extra dimensions, which some physicists suspect exist alongside the observed three dimensions of space and the fourth. the time.
In team theory, when gravity It spreads through additional dimensions, and is embodied in our universe as massive gravitons.
But these particles will interact weakly with ordinary matter, and only by the force of gravity.
This description is eerily similar to what we know about dark matter, which does not interact with light but has a gravitational effect that is felt everywhere in the universe. This gravitational effect, for example, is what prevents galaxies from flying away.
“The main advantage of massive gravitons as dark matter particles is that they interact only through gravity, and thus can escape attempts to detect their presence,” Kacchiapalia said.
In contrast, other dark matter candidates have proposed – such as the interaction of weak massive particles, axons, and neutrinos They can also be felt through their very subtle interactions with other forces and domains.
The fact that massive gravitons hardly interact via gravity with other particles and forces in the universe offers another advantage.
“Because of their very weak interactions, they decay so slowly that they remain stable throughout the life of the universe. For the same reason, they are produced slowly during the expansion of the universe and accumulate there until today,” Cacciapaglia said.
In the past, physicists thought gravitons were a likely candidate dark matter because the processes that produce them are so rare. As a result, gravitons will be generated at much lower rates than other particles.
But the team found that in picoseconds (trillionths of a second) after the great explosionHowever, more of these gravitons could have been created than previous theories suggested.
The study found that this boost was enough for massive gravitons to explain exactly how much dark matter we find in the universe.
“The reinforcement was a shock,” Kachiapalia said. “We had to run many tests to make sure that the result was correct, as it results in a paradigm shift in the way we consider massive gravitons as potential candidates for dark matter.”
Because massive gravitons are formed under the energy scale in Higgs bosonfreed from uncertainty related to higher energy scales, which current particle physics does not describe well.
The team’s theory links the physics studied in particle accelerators such as Large Hadron Collider With the physics of gravity.
This means powerful particle accelerators such as the Future Circular Collider at CERN, which should start operating in 2035, could look for evidence of potential dark matter particles.
“Probably our best shot at high-resolution particle collisions in the future,” Kachiapalia said. “This is something we are currently investigating.”
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