NEW SUBATOMIC PARTICLE DISCOVERED AT CERN
What a charmer: scientists working at the Large Hadron Collider have found a new kind of subatomic particle. The particle is a baryon (a particle consisting of three quarks) named Xi-cc++, and is part of a family of ‘doubly charmed baryons’ whose existence had previously been predicted by the Standard Model of particle physics, but never observed. The research, led by University of Glasgow physicist Dr Patrick Spradlin, was carried out at the Large Hadron Collider’s LHCb detector.
All the matter we see around us is comprised of protons and neutrons, which are baryons made of the lighter up and down quarks. Baryons that include the heavier charm, top, strange or beauty quarks decay almost instantly into protons and neutrons, making them hard to detect.
Many baryons have been observed with one heavy quark but Xi-cc++ is the first one that’s ever
“FINDING A NEW HEAVYQUARK BARYON IS OF GREAT INTEREST”
been seen with two heavy quarks – in this case two charm quarks.
“The properties of the newly discovered Xicc++ baryon shed light on a longstanding puzzle surrounding the experimental status of baryons containing two charm quarks, opening an exciting new branch of investigation for LHCb,” said Spradlin. The new baryon is around 3.5 times heavier than a proton or neutron, and has an electric charge twice that of a proton. The Glasgow team discovered over 300 Xi-cc++ particles lurking in last year’s LHCb data.
“Finding a new 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 researcher Giovanni Passaleva.