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Physicists baffled and delighted by 2 experiments that defy the rules

Preliminary results from two experiments suggest that something is wrong with the fundamental way physicists think the universe works, a prospect that has both baffled and excited the field of particle physics.

The smallest particles don’t quite do what is expected of them when circled around two different long-lasting experiments in the United States and Europe. The puzzling results – if proven correct – reveal major problems with the rulebook physicists use to describe and understand how the universe works at the subatomic level.

Theoretical physicist Matthew McCullough of CERN, the European Organization for Nuclear Research, said unraveling the mysteries could “take us beyond our current understanding of nature.”

The rulebook, called the Standard Model, was developed about 50 years ago. Experiments carried out over decades have repeatedly confirmed that his descriptions of the particles and forces that make up and govern the universe are pretty much on the right track. Until now.

“New particles, new physics might be just beyond our research,” said Alexey Petrov, particle physicist at Wayne State University. “It’s enticing.”

The closed US Department of Energy lab on Wednesday announced the results of 8.2 billion runs along a track outside Chicago that although most people are shaking physicists: the magnetic field around a fleeting subatomic particle is not what the Standard Model says it should be. This follows new results released last month by CERN’s Large Hadron Collider which found a surprising proportion of particles as a result of high-speed collisions.

Petrov, who was not involved in either of the two experiments, was initially skeptical of the Large Hadron Collider’s results when clues emerged in 2014. With the latest more comprehensive results, he said he was now “cautiously ecstatic. “.

The purpose of the experiments, explains theoretical physicist David Kaplan of Johns Hopkins University, is to separate the particles and find out if “something funny” is going on with the particles and the seemingly empty space between them.

“Secrets don’t just live in matter. They live in something that seems to fill all space and time. These are quantum fields, ”Kaplan said. “We put energy into the void and see what comes out of it.”

Both sets of results involve the strange fleeting particle called a muon. The muon is the heavier cousin of the electron which orbits the center of an atom. But the muon is not part of the atom, it is unstable and normally only exists for two microseconds. After being discovered in cosmic rays in 1936, it confused scientists so much that a famous physicist asked “Who ordered this?”

“From the very beginning, physicists were scratching their heads,” said Graziano Venanzoni, an experimental physicist at an Italian national laboratory, who is one of the best scientists in the American Fermilab experiment, called Muon g-2.

The experiment sends muons around a magnetized track that keeps the particles alive long enough for researchers to take a closer look. Preliminary results suggest that the magnetic “spin” of muons is 0.1% lower than what the Standard Model predicts. It might not sound like much, but to particle physicists it’s huge – more than enough to turn current understanding upside down.

Researchers need a year or two to complete the analysis of the results of all laps around the 14-meter (50-foot) track. If the results don’t change, it will count as a major discovery, Venanzoni said.

In addition, in the world’s largest atom breaker at CERN, physicists crushed protons there to see what happened next. One of the many separate experiments at one of the particle colliders measures what happens when particles called beauty or background quarks collide.

The Standard Model predicts that these beauty quark crashes should result in an equal number of electrons and muons. It’s a bit like flipping a coin 1,000 times and getting roughly the same number of heads and tails, said Chris Parkes, head of the Large Hadron Collider’s beauty experiment.

But that’s not what happened.

The researchers looked at data from several years and a few thousand accidents and found a difference of 15%, with many more electrons than muons, said experimental researcher Sheldon Stone of Syracuse University. .

Neither experiment has yet qualified as an official find as there is still a small chance the results will be statistical oddities. Running the experiments more often – either planned – could, within a year or two, meet the incredibly strict statistical requirements for physics to hail it as a discovery, the researchers said.

If the results hold, they would upset “every other calculation done” in the world of particle physics, Kaplan said.

“It’s not a fudge factor. This is something wrong, ”Kaplan said.

He explained that there may be some sort of undiscovered particle – or force – that could explain the two bizarre results.

Or it could be mistakes. In 2011, a strange discovery that a particle called a neutrino seemed to travel faster than light threatened the model, but this turned out to be the result of a loose electrical connection issue in the experiment.

“We checked all of our cable connections and did what we could to verify our data,” Stone said. “We’re pretty confident, but you never know.”

AP writer Jamey Keaten in Geneva contributed to this report.

Follow Seth Borenstein on Twitter at @borenbears.


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