The world’s largest atom smasher can be tweaked to hunt ‘dark world’ particles


Scientists have a new way to peer in physics’, the dark world.”

In a new paper, theoretical physicists say that they have a new plan for the search for theoretical particles that have never been observed. These particles, called long-lived particles, or LLPs, a window to dark matter and dark energy, which together 95% of the universe. Dark matter exerts a gravitational attraction on the ordinary matter and dark energy is thought to be the cause of the universe’s expansion to accelerate. But cannot be directly observed, because all of the interactions that they have with the luminous matter of the universe are weakened, Zhen said Liu, a postdoctoral researcher at the University of Maryland.

“They don’t talk with us,” Liu, one of the researchers who are working on the new plan, told Science.

But LLPs might be a way for the dark world to interact with the lighter. And Liu and his colleagues are of the opinion that by tweaking a number of the detectors in the world’s largest atom smasher, the Large Hadron Collider (LHC) near Geneva, Switzerland, physicists would be able to find them. [The 11 Greatest Unanswered Questions About Dark Matter]

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Parallel worlds

The “dark world, also known as the “hidden sector,” describes a series of hypothetical particles that would go further than the Standard Model of physics. ( The Standard Model explains protons, neutrons, electrons and all the strange subatomic particles that go along with them, such as quarks, muons, neutrinos and the Higgs boson.)

If all “normal” matter is in a valley, the dark world is in a parallel valley to a ridge about, Liu said. It takes an enormous amount of energy to climb that ridge, so particles in the dark world valley interact strongly with each other, but only slightly with that on the other side of the mountain. But some particles may be able to push through that barrier of the dark world into the one that we normally encounter through a process called quantum tunneling. These particles are probably not the dark-matter equivalent of stable particles such as protons or neutrons, Liu said, but would perhaps be more akin to the more unstable Standard Model particles.

It is that tunneling particles that the researchers are interested in finding. But these particles, if they exist, are rare, said Liantao Wang, a theoretical physicist at the University of Chicago. The LHC throws protons at each other at a dazzling pace, producing 1 billion collisions per second. That collisions shatter the protons in enormous numbers of known Standard Model particles. For scientists in search of the hidden sector, all the particles are just noise. The particles they’re interested in, Wang said, might appear only a few times per decade.

A new way

Wang, together with Liu and their colleagues, Jia Liu, the authors of the paper, published April 3 in the journal Physical Review Letters, suggests a way in order to catch a glimpse of these rare particles.

It all comes down to timing. LLPs, Wang said, should be massive and hulking compared to the Standard-Model particles that the LHC makes in bulk. Their slowness is the result of the large energy barrier that they must overcome just to make an impression on the world of normal matter, Liu said. But their snail’s pace is also a useful feature for physicists. Most of the elementary particles in the LHC travel at the speed of light and decay rapidly. The Higgs-boson, for example, has gone in just 10 to the minus 22 seconds, to transform it into a set of more stable particles. [Photos: The world’s Largest Atom Smasher (LHC)]

LLPs, though, is to live slowly, to a tenth of a second, Wang said. Also they travel slower than the speed of light. Therefore, the adjustment of the LHC’s detectors to find the particles that arrive too late, of their sensors the key must be to detect them.

“It is a very simple idea,” Wang said, “but it turns out to be surprisingly effective.”

Some of these adjustments will come naturally with the LHC’s upgrades, which is constantly now, Liu said. The particle accelerator will open again in 2021, with detectors that will be able to measure the timing of particle arrival times out of 10 more accurate than it currently can, he said. From there, he said, it is just a matter of a couple of software tweaks to take advantage of the LHC, the possibilities, and to ensure that the experimental physicists who use the collider to prioritize the search. Now, Wang and Liu said, they and their experimentalist colleagues, with a series of meetings to make sure everyone is on the same page.

“It’s going to happen,” Liu said.

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Originally published on Live Science.

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