The Proton and Neutron Just Got Two New Subatomic Cousins

CERN physicists announced the discovery of two types of baryons Wednesday: Xi_b'- and Xi_b*-.

Pierre Albouy/Reuters

Using the same massive particle accelerator that found the elusive Higgs Boson in 2012, physicists at CERN's Large Hadron Collider (LHC) announced that they discovered two new "heavy-weight" subatomic particles on Wednesday.

The LHC is a 17-mile long underground “racetrack” that accelerates two opposing beams of particles to speeds of 99.9999 percent the speed of light. The particles race around the LHC on a crash course, and when they collide, the temperatures soar to more than 100,000 times hotter than the center of the sun. At heats this extreme, the particles transform into a primordial form of matter known–in not-quite-technical terms–as a “subatomic soup.”

Within this ultra-hot mélange, new previously unseen forms of matter can take shape for fractions of a second. High-powered detectors analyze the medley and clue scientists into the presence of new subatomic material.

The newly announced particles are known as baryons, and are six times as massive as protons. Like protons, baryons are made up of three strongly-bound elementary particles called quarks, which are thought to be some of the smallest units of matter. The two newly discovered baryons have different spins, or directions in which their quarks configure. The finding helps physicists narrow down the different ways that quarks can be arranged, which provides clues into understanding the forces that keep them and the most basic building blocks of matter held together, according to CERN.

“There are maybe three-to-five such particles discovered each year,” Patrick Koppenburg, a CERN scientist from the Netherlands’ Nikhef Institute, said to The Wall Street Journal. “Here we have two in one go, which is quite extraordinary.” Previous theories within particle physics had predicted the existence of these two baryons, but the findings provide physicists with the results they need to strongly support those claims.

“Now we know exactly what the mass is,”  Koppenburg said. The findings have been submitted to the journal Physical Review Letters, but appear unpublished online today on Arxiv.

The particle physics community often meets new subatomic findings with skepticism. In 2011, a collaboration between CERN and the Italian OPERA experiment announced finding faster-than-light neutrinos, a discovery that was later undone after further investigation, as ScienceInsider reported in 2012. Even now, some physicists still debate whether or not physicists actually found the Higgs Boson. So these recent baryon discoveries will most likely be put through rigorous peer-review, before being widely accepted.