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Large Hadron Collider experiment reveals three exotic particles

Tetraquarks and other discoveries as CERN revs up for Run 3

Physicists at the Large Hadron Collider (LHC) have announced the observation of three never-before-seen particles as the accelerator kicks off its third run.

A new kind of "pentaquark" was spotted along with the first ever pair of "tetraquarks."

Quarks are elementary particles. There are "up", "down", "charm", "strange", "top", and "bottom." Combinations of quarks form hadrons, usually in groups of two or three. They can also group in fours and fives, however, they have only recently been observed by experiments such as the Large Hadron Collider beauty (LHCb).

The LHCb experiment looks at the differences between matter and antimatter and uses a series of sub-detectors to look for forward particles – those thrown forwards by a collision.

The results were presented today at a CERN seminar as the LHC prepared for another run at data collection. The LHC was first fired up in 2010 and this latest activity is expected to last for almost four years at a record energy of 13.6 trillion electronvolts (TeV).

The four big LHC experiments have been updated to cope with the results of the upgrade. The aforementioned LHCb experiment underwent a complete revamp to increase its data-taking rate by a factor of ten. ALICE (A Large Ion Collider Experiment), which is designed to study the physics of strongly interacting matter at extreme energy densities, "is aiming at a staggering fifty-fold increase in the number of recorded collisions," according to CERN.

The ATLAS and CMS detectors are similarly expected to record more collisions during the new run than the previous two runs combined.

"We will be focusing the proton beams at the interaction points to less than 10 micron beam size, to increase the collision rate. Compared to Run 1, in which the Higgs was discovered with 12 inverse femtobarns, now in Run 3 we will be delivering 280 inverse femtobarns. This is a significant increase, paving the way for new discoveries," said director for Accelerators and Technology Mike Lamont.

Beams have been circulating around the accelerator since April following the recommissioning of CERN's injector complex to operate with increased energy and higher intensity beams. The operators of the LHC are now ready to announce "stable beams," which is the point at which the experiments can start collecting data for analysis.

Run 3 will doubtless delight skeptics who will look at the extreme conditions (intended to be similar to those just after the Big Bang) generated by the accelerator with just a little nervousness, although the world didn't appear to end during the last two runs. CERN has said the thing is perfectly safe.

And now the metaphorical dial is being turned up to 11. ®

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