CERN Large Hadron Collider Uncovers New Class of Particles: Pentaquarks

It turns out that CERN's Large Hadron Collider has discovered a new class of particles known as pentaquarks. The new discovery could herald a new way to think about particle physics.

"The pentaquark is not just any new particle," said Guy Wilkinson, LHCb spokesperson, in a news release. "It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over fifty years of experimental searches. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we're all made, is constituted."

Petaquarks are essentially composed of four quarks and an antiquark. Until now, though, there's been inconclusive evidence for pentaquarks even though they were predicted.

In this latest study, the researchers looked for pentaquark states by examining the decay of a baryon into three other particles, a proton and a charged kaon. By studying the spectrum of masses for the three other particles and the proton, the scientists found that intermediate states were involved in their production.

"Benefitting from the large data set provided by the LHC, and the excellent precision of our detector, we have examined all possibilities for these signals, and conclude that they can only be explained by pentaquark states," said Tomasz Skwarnicki, LHCb physicist. "More precisely the states must be formed of two up quarks, one down quark, one charm quark and one anti-charm quark."

Currently, the researchers say that more studies are needed to distinguish the bonds between the quarks and see what else pentaquarks can teach them.

The findings are published in the journal Physical Review Letters.

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