LHC Discovers First New Particle - Chi_b (3P)

CERN physicists, analysing data from the Atlas experiment, have made their first new particle discovery at the Large Hadron Collider, known as Chi_b (3P), which will help scientists better understand the forces that hold matter together.

This is the first clear observation of a new particle since the LHC opened in 2009. The LHC is the largest facility exploring fundamental questions in "big physics" by colliding proton particles together.

Physicists said the Chi_b (3P), which like the Higgs boson, is a boson, portends a new way of combining a beauty quark and its antiquark so that they bind together. But whereas the Higgs is not made up of smaller particles, the Chi_b(3P) combines two very heavy objects via the same 'strong force' which holds the atomic nucleus together.

According to Professor Roger Jones, who works on the Atlas detector at the LHC, the Chi_b (3P) is a more excited state of Chi particles already seen in previous collision experiments. "The new particle is made up of a 'beauty quark' and a 'beauty anti-quark', which are then bound together," he said.

He noted that people have thought this more excited state should exist for years, but nobody has managed to see it until now.

"The Chi_b(3P) is a particle that was predicted by many theorists, but was not observed at previous experiments, such as in my previous work on the D-Zero experiment in Chicago," said Dr James Walder, a Lancaster research associate who worked on the analysis.

"It's also interesting for what it tells us about the forces that hold the quark and the anti-quark together - the strong nuclear force. And that's the same force that holds, for instance, the atomic nucleus together with its protons and the neutrons," Jones said.

The physicist explained that LHC discoveries are an important part of this quest because they add to the wider background knowledge.

"The better we understand the strong force, the more we understand a large part of the data that we see, which is quite often the background to the more exciting things we are looking for, like the Higgs," Jones noted.

"While people are rightly interested in the Higgs boson, which we believe gives particles their mass and may have started to reveal itself, a lot of the mass of everyday objects comes from the strong interaction we are investigating using the chi b," he concluded.