The LHCb experiment of the Large Hadron Collider (LHC) of CERN, the European Organization for Nuclear Research located in Switzerland, has discovered two new particles of the baryonic family , that is, those that are made up of quarks. They are Xi_b’- and Xi_b * – and, although they had already been described, they had not been seen until now. The finding has been published in the journal Physical Review Letters .
These new particles are baryons made of three quarks and held together by the strong nuclear force, but these types of quarks are different and six times more massive than a proton : they both contain a beauty quark (b), a strange (s) and a down (d), while the proton is made up of two quarks above (u) and one below (d).
“Nature has been generous and has given us two particles for the price of one, ” says study co-author Matthew Charles with satisfaction.
In addition to the masses of these two new particles, the researchers studied their production rates and their decay widths (a measure of their stability), among other parameters, and the results fit with the predictions of Quantum Chromodynamics (QCD), part of the Standard Model of Particle Physics (theory that describes elementary particles and their interactions).
“If we want to find new physics beyond the Standard Model, we need an accurate image first. These high precision studies help us to differentiate between effects of the Standard Model and anything else new or unexpected in the future ”, explains Patrick Koppenburg, study co-author.
