CERN celebrates 'Run 3' — and 3 new exotic particles

GENEVA (AN) — Scientists cheered as the world's biggest and most powerful atom smasher started recording high-energy collisions at the unprecedented energy of 13.6 trillion electronvolts, raising the prospect of more discoveries about the universe’s fundamental properties.

The Large Hadron Collider's third years-long run known as 'Run 3' — its third time creating high-energy collisions of protons to investigate dark matter, antimatter and the creation of the universe since 2008 — began on Tuesday with its detectors once again recording those collisions between protons sent in opposite directions around its 27-kilometer ring in a vast complex on the Swiss-French border.

Also Tuesday, physicists at the European Organization for Nuclear Research, known by its French acronym CERN, told a seminar they observed three new particles.  The new kind of pentaquark and first-ever pair of tetraquarks, including a new type, "will help physicists better understand how quarks bind together into these composite particles," CERN said.

Ramping up the energy

And on Monday, CERN celebrated the 10-year anniversary of its landmark discovery of the Higgs boson, the elusive subatomic particle believed to give all matter in the universe size and shape. The 2012 announcement unveiled a “missing cornerstone of physics” predicted by scientists almost a half-century before.

CERN restarted the LHC in April, after a shutdown of more than three years to allow for maintenance, consolidation and upgrades. It began at a lower energy level of 450 billion electronvolts, or 450 GeV, in preparation for Run 3's high-intensity, high-energy collisions.

Scientists then had to gradually recommission LHC to safely ramp up the energy and intensity of beams before delivering collisions to experiments at 13.6 TeV. The LHC has a limited life-span, and is sometimes shut down for repairs or upgrades.

It is now set to run "for close to four years at the record energy of 13.6 TeV, providing greater precision and discovery potential," CERN said. "Increased collision rates, higher collision energy, upgraded data readout and selection systems, new detector systems and computing infrastructure: all these factors point to a promising physics season that will further expand the already very diverse LHC physics program!"

Back to the future: high-luminosity mode

The newly upgraded LHC will be used to probe the nature of the Higgs boson with unprecedented precision and in new channels, scientists say, and it may observe previously inaccessible processes. They say it will be able to improve the measurement precision of numerous known processes addressing fundamental questions, such as the origin of the matter–antimatter asymmetry in the universe.

Scientists say they also will study the properties of matter under extreme temperature and density, and will also be searching for candidates for dark matter and for other new phenomena, either through direct searches or indirectly through precise measurements of properties of known particles.

“We’re looking forward to measurements of the Higgs boson decay to second-generation particles such as muons. This would be an entirely new result in the Higgs boson saga, confirming for the first time that second-generation particles also get mass through the Higgs mechanism,” CERN theorist Michelangelo Mangano said.

After that run, the High Luminosity Large Hadron Collider is expected to operate by the start of 2028. Luminosity refers to the number of collisions among sub-atomic particles. The higher the luminosity, the more data become available. The upgrades will increase the number of proton collisions for experiments.

The HL-LHC, an upgrade of the LHC, "aims to achieve instantaneous luminosities a factor of five larger than the LHC nominal value, thereby enabling the experiments to enlarge their data sample by one order of magnitude compared with the LHC baseline program," CERN said.