Researchers discovered two new particles through CERN's Large Hadron Collider.
The particles, dubbed Xi_b'- and Xi_b*, are part of the baryon family, and were previously predicted by the quark model but never actually observed, CERN reported. The findings were made as part of the LHCb experiment.
"Nature was kind and gave us two particles for the price of one," said Matthew Charles of the CNRS's LPNHE laboratory at Paris VI University. "The Xi_b'- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn't have seen it at all using the decay signature that we were looking for."
Like protons, the newly-discovered particles are baryons. These types of particles are composed of three quarks bound together by a strong force. The new X_ib particles both contain one beauty (b), one strange (s), and one down (d) quark, and are more than six times the mass of protons.
"This is a very exciting result. Thanks to LHCb's excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background," said Steven Blusk from Syracuse University in New York. "It demonstrates once again the sensitivity and how precise the LHCb detector is."
In addition to these particles' mass the researchers also looked at their relative production rates, widths, and levels of instability. Their findings proved to match up with predictions made by the theory of Quantum Chromodynamics (QCD). The theory is part of the Standard Model of particle physics.
"If we want to find new physics beyond the Standard Model, we need first to have a sharp picture," said LHCb's physics coordinator Patrick Koppenburg from Nikhef Institute in Amsterdam. "Such high precision studies will help us to differentiate between Standard Model effects and anything new or unexpected in the future."
The findings were published in a recent edition of the journal Physical Review Letters.