Two New Subatomic Particles Found Using Large Hadron Collider, Scientists Say

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Discovery Helps Understanding of How Things Operate on Very Small Scale

Technicians worked on part of the Large Hadron Collider at CERN in July. REUTERS.

Scientists using the atom-smashing machine known as the Large Hadron Collider on Wednesday said they had observed two never-seen-before particles, a discovery that refines physicists’ understanding of how elementary particles interact and the forces between them.

Theoretical models had predicted the existence of the particles. Scientists used the collider to smash particles together and then sifted through the result to pinpoint the existence of the new particles and identify their mass.

“Now we know exactly what the mass is,” said Patrick Koppenburg from the Netherlands’ Nikhef Institute. Dr. Koppenburg is currently based at the European Organization for Nuclear Research, or CERN, which operates the world’s largest and most powerful particle accelerator, the Large Hadron Collider.

The new particles are six times as large as the proton, the positively charged subatomic particle that is found in the nucleus of every atom.

The new particles are members of the baryon family, which also includes protons and neutrons. Baryons are made from three quarks, which are the building blocks of matter.

The observation of the baryons isn’t of the same consequence as CERN’s 2012 discovery of the Higgs boson, which is a fundamental particle that helps explain how particles get their mass. But because it is extremely hard to model how baryons behave, the new discovery is a significant contribution to our understanding of how things operate on the scale of the very small.

“There are maybe three to five such particles discovered each year,” said Dr. Koppenburg. “Here we have two in one go, which is quite extraordinary.”

The measurements that pinpointed the baryons were based on data collected at the Large Hadron Collider during 2001 and 2012. It is currently shut down and is scheduled to restart by the spring and to operate at higher energies and using more intense beams than before.

This article originally appeared at The Wall Street Journal. Copyright 2014.

[Tweety.Abd]

Significance of the discovery

The two discovered particles are the xi(sub)b(prime) and xi(sub)b(star). Both of them are baryons, which mean they contain three quarks. The quarks are the up, strange and bottom. CMS discovered the xi(sub)b a while ago and that baryon has the same quark content. What is different about these baryons is that, for the prime baryon, the quarks are scrambled and moving much faster...essentially like an excited atom. In the star baryon, it is like the xi(sub)b but with the quark spins pointing in different directions.

Both of these particles were predicted by quantum chromodynamics (QCD) theory, so they are a confirmation discovery, not an unexpected one. However, this is a case of a very complex and rare combination of quarks, moving in a very complicated way. Discovering these sorts of things are very important, as they help validate a very complex theory.