Operating at unprecedented luminosities, the LHCb experiment at CERN has revealed a system of five “glue-like” particles that interact through the strong and weak nuclear forces. The particles are called glue-like because they’re expected to shed light on how quarks bind together. This discovery could help us to fill out a “periodic table” of subatomic particles.
This discovery was made possible thanks to the large dataset accumulated during the first and second runs of the Large Hadron Collider. With so much data — really, the LHC’s cup runneth over with data because of all the collisions they’ve been doing — scientists were able to isolate the signals from the system of particles with high confidence. Unlike prior false alarms, this is no statistical fluke.
According to CERN:
The particles were found to be excited states – a particle state that has a higher energy than the absolute minimum configuration (or ground state) – of a particle called “Omega-c-zero”, Ωc0. This Ωc0 is a baryon, a particle with three quarks, containing two “strange” and one “charm” quark. Ωc0 decays via the strong force into another baryon, called “Xi-c-plus”, Ξc+ (containing a “charm”, a “strange” and an “up” quark) and a kaon K-. Then the Ξc+ particle decays through the weak force in turn into a proton p, a kaon K- and a pion π+.
At the relativistic speeds these particles were going, their mass is perhaps better stated in terms of energy. Expressed in mega-electron-volts (MeV), these particles have masses of 3000, 3050, 3066, 3090 and 3119 MeV, respectively.
Next on the list for physicists will be making sure our theories agree with this data. Scientists have been working on a “periodic table” for subatomic particles, populated by all the different colors, flavors and other attributes of those elementary entities. This is the work of decades, but it’s meant to fill in our understanding of physics so that we’ll have finer control of the ways we use it in everyday life — little stuff like semiconductors, medical imaging, and telecommunications.
Prof. William Trischuk explained to Phys.org: “The Standard Model is very rational. We can write down how it works. But we don’t understand why it works… Colleagues in theoretical physics have got lots of great ideas and have written hundreds of papers, but physics is an observational science. We want to peel back the next layer of the Standard Model and put some order to it.”
To that end, it will be important for particle physicists to determine the quantum numbers of these new particles. Quantum numbers are integers used to identify the quantum properties (like spin) of a specific particle. This discovery is expected to contribute to understanding how the three constituent quarks are bound inside a baryon by the strong nuclear force, responsible for holding atomic nuclei together. It should also help us to more fully characterize multi-quark states, such as tetraquarks and pentaquarks.
More detailed information is available in the paper and from CERN.
Now read: How does the LHC work?