LHC researchers find new subatomic particle

Researchers reported yesterday that in the flying debris from the collisions of protons, at the CERN particle physics laboratory outside Geneva, they had identified a particle that had long been predicted but had not been detected until now.

In an experiment with the Large Hadron Collider (LHC) at CERN, scientists counted over 300 Xi-cc++ baryons, each consisting of two heavy charm quarks and one up quark.

According to experts, the new particle, known as Xi-cc++ (pronounced ka-sigh-see-see-plus-plus), could provide fresh insight into how tiny, particles called quarks, which were the building blocks of protons and neutrons, interacted with each other.

Protons and neutrons, which accounted for the bulk of ordinary matter, were made of two types of quarks - up and down. A proton consisted of two up quarks and one down quark, while a neutron contained one up quark and two down quarks. These quark triplets were known as baryons.

There were also heavier quarks with names like strange, charm, top, bottom - and baryons, which contained permutations of heavier quarks.

The discovery was in line with the Standard Model, the prevailing understanding of how the smallest bits of the universe behaved, and did not seem to point to new physics, according to experts.

''The existence of these particles has been predicted by the Standard Model,'' said Patrick Spradlin, a physicist at the University of Glasgow who led the research, The New York Times reported. ''Their properties have also been predicted.''

"Finding a doubly heavy-quark baryon is of great interest as it will provide a unique tool to further probe quantum chromodynamics, the theory that describes the strong interaction, one of the four fundamental forces," said Giovanni Passaleva in a release yesterday.

Passaleva is a spokesperson for the LHC experiment that produced the new particle for a fraction of a second by smashing protons together.