LHC double heavy particle to shine light on strong force

Scientists have detected a new particle at the Large Hadron Collider at Cern.

The discovery will help researchers learn more about the so-called "strong force" which holds the centres of atoms together.

The existence of the new particle was theoretically predicted but this is the first time it has been identified.

The details of the Xi-cc++ particle were presented at a high-energy physics conference in Venice.

The study was carried out at the LHCb experiment and led by Dr Patrick Spradlin of Glasgow University. He said that the discovery would "shed light on a longstanding puzzle and open an exciting new branch of investigation".

His colleague, Prof Paul Soler, also from Glasgow University, described the development as "a new frontier in understanding the strong force".

Nearly all the matter that we see around us is made of neutrons and protons, which form the centres of atoms. These are made up of three smaller particles called quarks which can be either light or heavy.

There are, however, six different types of quarks which combine in different ways to form other kinds of particle. Those that have been detected so far contain at most, one heavy quark.

This is the first time that researchers have confirmed the existence of one with two heavy quarks. According to Prof Guy Wilkinson of Oxford University, there is an intriguing difference between the new particle and the ones that have been discovered before.

"In contrast to other particles of this type, in which the three quarks perform an elaborate dance around each other, a particle with two heavy quarks is expected to act like a planetary system, where the heavy quarks are like two stars orbiting one around the other, with the lighter quark orbiting around this binary system."

The research team will now measure the properties of the Xi-cc++ to establish how this new arrangement of quarks behaves and how the strong force holds the system together. They also expect to find more double heavy quark particles.

Another unusual property of the particle is that it has two positive charges double that of the proton and it is four times heavier.

The researchers have submitted a paper reporting these findings to the journal Physical Review Letters.

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