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Posted on 18 Apr 2019
"A particularly interesting possibility is that these long-lived dark particles are coupled in some way to the Higgs boson – that the Higgs is actually a portal to the dark world," said LianTao Wang, physicist at the 39, University of Chicago, referring to the last reserve particle in the great theory of physicists on the functioning of the universe, discovered at the LHC in 2012. "We know for sure that there is a dark world and that it contains more energy than ours. It is possible that the Higgs can decompose into these long-lived particles. "
Now that they have identified the Higgs boson, scientists at the Large Hadron Collider have set their sights on an even more difficult target. A new paper describes a method for directly detecting "black world" particles using the Large Hadron Collider. Until now, we have only been able to perform measurements and indirect simulations, such as visualization of dark matter.
All around us there is dark matter and black energy – the invisible substance that binds the galaxy together, but no one has been able to detect it directly.
CERN – The LHC announces a new discovery and mystery of Higgs: "Does it interact with dark matter particles?"
Wang, who is studying how to find signals in large particle accelerators, alongside scientists from UChicago-affiliated University and Laboratory Fermil, thinks they could guide us to his footsteps . in an article published April 3 in Physical Review Letters, they presented an innovative method for tracking dark matter in the LHC (image below) by exploiting the slightly slower rate of a potential particle.
While the world of darkness represents more than 95% of the universe, scientists know that it exists through its effects – as a poltergeist, you can only see it when it is pushing back something from a shelf. For example, we know that dark matter is visible because we can see gravity acting – it prevents our galaxies from shattering.
Theorists believe that there is a particular type of dark particle that only occasionally interacts with normal matter. It would be heavier and last longer than other known particles, with a lifespan of up to one tenth of a second. The researchers believe that this particle can be caught in proton collisions that the LHC creates and measures constantly.
"Unknown dark energy" – Could this be the Symmetron field that invades space, like the Higgs field
The only problem is to sort these events among the rest; There is more than a billion collisions per second in the LHC, of a length of 27 km, and each of them sends a subatomic spraying of glitter in all directions.
Wang, Jia Liu, a postdoctoral researcher at UChicago, and Zhen Liu, a scientist at Fermilab (now at the University of Maryland), have proposed a new way of looking at exploiting a particular aspect of such a dark particle. "If it is so heavy, its production costs energy, so its momentum would not be important: it would move more slowly than the speed of light," said Liu, the first author of the study.
This delay would differentiate it from the rest of the normal particles. Scientists would only need to adjust the system to look for the particles produced then disintegrate a little slower than anything else.
Is dark matter a cosmological relic? – "Higgs particles could indicate the existence of a new mechanism"
The difference is in the order of a nanosecond – a billionth of a second – or less. But the LHC already has enough sophisticated detectors to detect this difference. A recent study using the data collected in the last analysis revealed that the method should work and that detectors will become even more sensitive as part of the ongoing upgrade.
"We expect this method to increase our sensitivity to long-lived dark particles by more than an order of magnitude, while using the capabilities we already have at the LHC," said Liu.
The experimenters are already working on the construction of the trap: when the LHC will reignite in 2021, after having increased tenfold, the three main detectors will implement the new system, the scientists announced. "We think it has great potential for discovery," Liu said.
"If the particle is there, we just have to find a way to unearth it," Wang said. "Usually the key is to find the question to ask."
The Daily Galaxy via the University of Chicago
Image credits: Survey of dark matter with children back to top. LHC image thanks to Laurent Egi
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