Synopsis: Five Charming New Baryons

The discovery of five new baryonic states at the Large Hadron Collider could shed light on the strong nuclear force.
Synopsis figure
CERN

Even at the most powerful particle accelerator on Earth, the discovery of a new particle is a big deal. Finding five new baryons in one go, as the Large Hadron Collider beauty experiment (LHCb) has done, is truly historical. The result will help researchers refine theories of the strong interaction, which binds quarks together in conventional baryons, like protons and neutrons, and in more exotic ones, like tetraquarks and pentaquarks.

The five new particles are excited states of the Omega-c-zero baryon (Ωc0), which is made up of one charm quark and two strange quarks. After the Ωc0 was discovered in 1994, physicists predicted the existence of its heavier excited states. But the very low production rates of these particles and their complex decay modes made them hard to observe. LHCb succeeded in seeing the states by monitoring the products of their decay: each baryon first decays via the strong force into another baryon called Ξc+, which then decays via the weak force into a proton, a kaon, and a pion.

Thanks both to the ultrasensitive detectors that are able to distinguish the final products of the decay, and to the accumulation of large datasets from LHC’s first and second runs, LHCb was able to infer the presence of five excited states of Ωc0. The particles, whose names reflect their masses in MeV, are Ωc(3000)0, Ωc(3050)0, Ωc(3066)0, Ωc(3090)0, and Ωc(3119)0. The collaboration now intends to measure the spin and parity values of each particle. These quantities will help researchers establish whether the five states can fit into the quark model as standard baryons or whether they have a more exotic nature like pentaquarks.

This research is published in Physical Review Letters.

–Matteo Rini

Matteo Rini is the Deputy Editor of Physics.


Features

More Features »

Subject Areas

Particles and Fields

Previous Synopsis

Atomic and Molecular Physics

Cooling Multiple Atoms in a Cavity

Read More »

Next Synopsis

Energy Research

Protons in the Fast Lane

Read More »

Related Articles

Synopsis: How to Untangle Quark and Gluon Jets
Particles and Fields

Synopsis: How to Untangle Quark and Gluon Jets

Inspired by a text-mining technique, scientists have developed a more direct way to distinguish quark jets from gluon jets in high-energy particle collisions. Read More »

Viewpoint: Sizing Up the Top Quark’s Interaction with the Higgs
Particles and Fields

Viewpoint: Sizing Up the Top Quark’s Interaction with the Higgs

A proton collision experiment at CERN provides a new handle on the Higgs boson’s interaction with the heaviest of the quarks. Read More »

Synopsis: OPERA’s Final Stamp on Neutrino Oscillations
Particles and Fields

Synopsis: OPERA’s Final Stamp on Neutrino Oscillations

The final analysis of data collected by the OPERA experiment improves the precision of measurements of neutrinos oscillating between muon and tau flavors. Read More »

More Articles