Day: April 7, 2022

Key Particle Weighs in a Bit Heavy, Confounding Physicists 

The grand explanation physicists use to describe how the universe works may have some major new flaws to patch after a fundamental particle was found to have more mass than scientists thought.

“It’s not just something is wrong,” said Dave Toback, a particle physicist at Texas A&M University and a spokesperson for the U.S. government’s Fermi National Accelerator Lab, which conducted the experiments. If replicated by other labs, “it literally means something fundamental in our understanding of nature is wrong.”

The physicists at the lab crashed particles together over 10 years and measured the mass of 4 million W bosons. These subatomic particles are responsible for a fundamental force at the center of atoms, and they exist for only a fraction of a second before they decay into other particles.

“They are constantly popping in and out of existence in the quantum froth of the universe,” Toback said.

The difference in mass from what the prevailing theory of the universe predicts is too big to be a rounding error or anything that could be easily explained away, according to the study by a team of 400 scientists from around the world published Thursday in the journal Science.

The result is so extraordinary it must be confirmed by another experiment, scientists say. If confirmed, it would present one of the biggest problems yet with scientists’ detailed rulebook for the cosmos, called the standard model.

Duke University physicist Ashutosh V. Kotwal, the project leader for analysis, said it’s like discovering there’s a hidden room in your house.

Undiscovered particle?

Scientists speculated that there may be an undiscovered particle that is interacting with the W boson that could explain the difference. Maybe dark matter, another poorly understood component of the universe, could be playing a role. Or maybe there’s just new physics involved that they just don’t understand at the moment, researchers said.

The standard model says a W boson should measure 80,357,000 electron volts, plus or minus six.

“We found it slightly more than that. Not that much, but it’s enough,” said Giorgio Chiarelli, another scientist for the Fermi team and research director for the Italian National Institute for Nuclear Physics. The Fermi team’s scale put the W boson at a heftier 80,433,000 electron volts, plus or minus nine.

It doesn’t seem like a big difference, but it is a huge one in the subatomic world.

But both the team and experts not involved in the research said such a big claim requires extra proof from a second team, which they don’t have yet.

“It’s an incredibly delicate measurement. It requires understanding of various calibrations of various little effects,” said Claudio Campagnari, a particle physicist at the University of California-Santa Barbara, who wasn’t part of the Fermi team. “These guys are really good. And I take them very seriously. But I think at the end of the day what we need is a confirmation by another experiment.”

Earlier, less precise measurements of the W boson by other teams found it to be lighter than predicted, so “maybe there is just something wonky about this experiment,” said Caltech physicist Sean M. Carroll, who wasn’t part of the research and said it was “absolutely worth taking very seriously.”

‘Nature has facts’

The finding is important because of its potential effect on the standard model of physics.

“Nature has facts,” Duke’s Kotwal said. “The model is the way we understand those facts.”

Scientists have long known the standard model isn’t perfect. It doesn’t explain dark matter or gravity well. If scientists have to tinker with it to explain these findings, they have to make sure the changes don’t ruin mathematical equations that now explain and predict other particles and forces well, researchers said.

It is a recurring problem with the model. A year ago, a different team found another problem with the standard model and how muons react.

“Quantum mechanics is really beautiful and weird,” Toback said. “Anyone who has not been deeply troubled by quantum mechanics has not understood it.”

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Space Travelers Speak with VOA

The first-ever married couple to fly on a commercial spacecraft speaks with VOA. Plus, an all-amateur flight crew prepares for a trip to the International Space Station, and a milestone in space-based racial equality. Arash Arabasadi brings us The Week in Space.

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JD.com Founder Richard Liu Leaves CEO Post

Chinese e-commerce company JD.com said Thursday that its founder Richard Liu has left his position as CEO, the latest Chinese billionaire founder to step aside amid increased government scrutiny of the country’s technology industry.

Liu will hand over the reins to JD.com’s president Xu Lei, according to a company statement. Liu will remain as the chairman of the board and continue to focus on JD.com’s “long-term strategies, mentoring younger management, and contributing to the revitalization of rural areas,” the statement said.

“I’ll devote more of my time to JD’s long-term strategies and future drivers as we continue to work on the most challenging yet valuable things,” Liu said.

Liu is the latest in a string of Chinese technology company founders who have stepped down from leadership positions in recent years. Last year, e-commerce firm Pinduoduo’s founder Colin Huang resigned as chairman and Bytedance founder Zhang Yiming also left his position as chairman of the firm.

The departures came as Beijing cracked down on the country’s once-freewheeling technology industry over antitrust concerns and fears that China’s technology giants were wielding too much influence over society. JD.com’s stock price has plunged 27% over the past year. Its New York-listed stock closed down 3% to $59.07 on the Nasdaq ahead of the announcement Thursday.

Like many Chinese technology companies, JD.com’s finances have suffered over the past year. The company reported a net loss of 5.2 billion yuan ($817 million) for the fourth quarter of 2021, compared to a net income of 24.3 billion yuan ($3.8 billion) in the previous year, even as revenue grew 23%.

E-commerce firms like JD.com and rival Alibaba have been suffering from economic headwinds and a slowdown in consumption, as well as increased competition from other players such as short-video companies like Kuaishou that have begun incorporating e-commerce functions into their platforms.

In 2018, Liu was arrested in Minnesota in the U.S. after a Chinese university student accused him of raping her in her apartment after they both attended a dinner party. Liu was exonerated after prosecutors found there was not enough evidence to press charges. The student later sued Liu in a civil lawsuit, seeking more than $50,000 in damages.

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