CERN discovers two new subatomic particles

  • PTI, Geneva
  • Updated: Nov 19, 2014 18:17 IST

Two new subatomic particles that could widen our understanding of the universe have been discovered, scientists at CERN announced on Wednesday.

The collaboration for the LHCb experiment at CERN's Large Hadron Collider discovered the two new particles belonging to the baryon family.

A baryon is a composite subatomic particle made up of three quarks. The particles were predicted to exist by the quark model but had never been seen before.

A related particle was found by the CMS experiment at CERN in 2012. Like the well-known protons that the LHC accelerates, the new particles are baryons made from three quarks bound together by the strong force.

The types of quarks are different, though: the new particles both contain one beauty (b), one strange (s), and one down (d) quark, CERN said in a statement.

Thanks to the heavyweight b quarks, they are more than six times as massive as the proton. But the particles are more than just the sum of their parts: their mass also depends on how they are configured.

"Nature was kind and gave us two particles for the price of one," said Matthew Charles of the CNRS's LPNHE laboratory at Paris VI University.

"This is a very exciting result. Thanks to LHCb's excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background," said Steven Blusk from Syracuse University in New York.

"It demonstrates once again the sensitivity and how precise the LHCb detector is," said Blusk. As well as the masses of these particles, the research team studied their relative production rates, their widths - a measure of how unstable they are - and other details of their decays.

The results match up with predictions based on the theory of Quantum Chromodynamics (QCD), researchers said. QCD is part of the Standard Model of particle physics, the theory that describes the fundamental particles of matter, how they interact and the forces between them.

Testing QCD at high precision is a key to refine our understanding of quark dynamics, models of which are tremendously difficult to calculate.

The measurements were made with the data taken at the LHC during 2011-2012. The findings were published in the journal Physical Review Letters.

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