CERN scientists track down two new particles thanks to Large Hadron Collider

20 Nov 2014

The Large Hadron Collider. Image via CERN

Scientists at research centre CERN in Switzerland claim to have found two new particles in the baryon family, discoveries that could lead to greater knowledge of our solar system.

Hardly the most interesting of names, ‘Xi_b’-’ and ‘Xi_b*-’ were predicted to exist by the quark model but had never been seen before.

Like the well-known protons that CERN’s Large Hadron Collider (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 X_ib particles both contain one beauty (b), one strange (s), and one down (d) quark.”

CERN’s results match up with predictions – apparently made by Canadian physicists Randy Lewis Richard Woloshyn – based on the theory of Quantum Chromodynamics (QCD).

Lewis said he saw the paper when it was first published online, telling CBC, “I saw the title (and) I thought, ‘Oh, I predicted those — I wonder how it turned out?’ I looked up their numbers and I said, ‘Yeah, that looks a lot like what I predicted — great!’”

Exciting result: Large Hadron Collider is great

“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.”

Blusk acknowledged he was specifically looking for the kinds of particles that were discovered, based on the predictions of scientists like Lewis and Woloshyn.

“We did have good reason to believe those particles would be there,” he said, although he didn’t know whether there would be one or two.

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

“The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

The measurements were made with the data taken at the LHC during 2011-2012. The LHC is currently being prepared – after its first long shutdown – to operate at higher energies and with more intense beams. It is scheduled to restart by spring 2015.

Gordon Hunt was a journalist with Silicon Republic