New source of matter antimatter asymmetry

For the first time the LHCb experiment at CERN has measured an asymmetry between baryonic matter and antimatter. Baryons are particles composed of three quarks as the protons and neutrons that constitutes the matter that we know. Such asymmetries have been measured in the past in the decays of particles composed of two quarks (quark and anti-quark) called K and B mesons, but were never observed in the decay of any baryon. The study of  matter antimatter asymmetries is crucial to answer questions on the evolution of the Universe and in particular how it was possible to reach a state of complete absence of antimatter, if at the the origin matter and antimatter were produced in equal amount, as required by the Big Bang theory.


To perform this measurement at CERN were isolated for the first time about 6000 events of rare decays of Lambda-b baryons- particles about 6 times heavier than the neutron, due to the fact that contain a heavy quark called “bottom” – into a proton and 3 pions. Nicola Neri (researcher at INFN Milan) and his research team conducted the study now published in Nature Physics. According to Neri it is a first evidence that must be confirmed with more data but that would open new research opportunities: “LHCb has the ability to measure precisely asymmetries between matter and antimatter even in heavy baryons processes and it will be even more in future after the upgrade of the LHCb detector”. The LHCb group at INFN Milano led by Neri is responsible for the construction of the new silicon tracker to allow to collect a larger amount of data and possibly answer many questions still open on the evolution of the Universe.

Additional reading: