The Large Hadron Collider (LHC) will restart on Friday after a three-year hiatus and is expected to resolve scientific ambition as to whether a mysterious anomaly could point to the existence of a fifth fundamental force of nature.
Attractive findings last year have revived hopes that the 20-kilometer collider could lead to a second blockbuster discovery, more than a decade after the Higgs boson.
Dr Mitesh Patel, an elementary particle physicist at Imperial College London, whose team was responsible for last year’s study, said: “We are entering this series with more optimism that there may be a revolution. Fingers crossed.”
So far, everything found at the LHC – including Higgs – is in line with the so-called standard model. This is the leading theory of particle physics from the 1970s, but it is known to be incomplete because it fails to explain some of the deepest mysteries in physics, such as the nature of dark matter.
However, data collected in the LHCb experiment, one of four huge particle detectors at Cern in Switzerland, appear to indicate that the particles behave in a way that cannot be explained by the standard model.
The experiment looks at the decay of particles called beauty quarks, which are expected to decay at the same rate of electrons and their heavier cousins, muons. However, beauty quarks seem to turn into muons 15% less often, suggesting that an unknown factor – a potentially new force – is tilting the scales. Two of the best candidates include hypothetical force-bearing particles called leptoquars or Z prime numbers.
“The stakes are extremely high,” Patel said. “If we confirm this, it will be a revolution of a kind we have never seen – certainly in my life. You don’t want to confuse him. “
Before the LHC was shut down for an upgrade in 2018, the team gathered enough data to speculate that the odds are approximately a thousand for one of the results, which happened by accident. But the gold standard for particle physics is stricter at a confidence level of 3.5 m, which means more data is needed before a discovery can be announced. There is also a long-standing possibility that some unknown experimental bug may explain the findings.
“When you show this result to particle physicists, the first instinct is ‘You guys fucked up,’ not a new force in nature,” Patel said. “We physicists like to be out of security and on the other side.
Over the past year, anticipation has been heightened by additional intriguing allusions to physics beyond the standard model seen in other experiments, including recent unexplained discoveries by Fermilab in the United States.
“There seems to be a collection of loose threads now,” said Professor John Butterworth of the University College London, who is working on the LHC’s Atlas experiment. “It made me think that there might be something to this or that.”
If the LHC fails to uncover new science beyond the standard model, Butterworth said, it will not be a failure, but it will leave the field “in a little trouble” as to where to look next.
The third cycle, which is expected to last until 2026, follows an upgrade that involves the installation of additional powerful magnets designed to press the protons inside the collider into finer, denser rays. This will increase the rate of collision of particles in the accelerator, which means that scientists will be able to observe rarer events with greater accuracy.
Ashutosh Kotual, an experimental particle physicist at Duke University in the United States and co-leader of a research group at the LHC’s Atlas experiment, said: “The potential for discovering new ideas is still so great. It is worth noting that the data we have collected so far is only one tenth of the total number we plan. It’s too early to lose heart. “
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