Physicists at CERN have made a stunning discovery involving a particle that is almost four times heavier than proton. The new particle, named Xi-cc++ is part of a family of “doubly-charmed baryons” that are predicted to exist by the Standard Model theory of particle physics.
Theoretically the particle has been in existence for quite some time now, but physicists have been looking for such baryons with two heavy quarks for many years. The mass of the newly identified particle is about 3621 MeV, which is almost four times heavier than the most familiar baryon, the proton, a property that arises from its doubly charmed quark content. It is the first time that such a particle has been unambiguously detected.
Chris Parkes, deputy spokesperson for the LHCb experiment and Professor of experimental particle physics at the University of Manchester, said: “This discovery opens up a new field of particle physics research.
Baryons that have been observed so far are all made of, at most, one heavy quark such as a bottom or charm quark. However, there are six types of existing quarks, and theoretically many different potential combinations could form other kinds of baryons.
Measuring the properties of the Xi-cc++ will help to establish how a system of two heavy quarks and a light quark behaves. Important insights can be obtained by precisely measuring production and decay mechanisms, and the lifetime of this new particle.
The observation of this new baryon proved to be challenging and has been made possible owing to the high production rate of heavy quarks at the LHC and to the unique capabilities of the LHCb experiment, which can identify the decay products with excellent efficiency. The Xi-cc++baryon was identified via its decay into a Λc+ baryon and three lighter mesons K-, π+ and π+.
This result is based on 13 TeV data recorded during run 2 at the Large Hadron Collider, and confirmed using 8 TeV data from run 1.