In a new breakthrough presented at the Rencontres de Moriond conference, the international LHCb collaboration revealed a hitherto elusive phenomenon: an asymmetry in the decay of beauty-lambda (Λb) baryons.
This finding, obtained after analyzing more than 80,000 events at the Large Hadron Collider , provides compelling evidence of charge-parity (CP) violation in particles made up of three quarks.
Baryons also break symmetry
CP violation had already been observed in a class of particles called mesons since the 1960s. However, detecting it in baryons, such as beauty lambdas, required an immense volume of data and extreme precision in identifying their decay products. According to spokesperson Vincenzo Vagnoni, this phenomenon reflects a difference in behavior between matter and antimatter, key to understanding why the universe is composed predominantly of matter.
The study showed a 2.45% discrepancy between the decay rates of Λb and its antimatter counterpart. This difference, with a statistical significance greater than five standard deviations, meets the criteria for confirming CP violation in this type of particle.
Implications for future physics
Although the Standard Model anticipates the existence of CP violations, the observed magnitude is insufficient to explain the preeminence of matter in the universe. This gap between theory and evidence opens the possibility of still unknown mechanisms. Future research will seek to expand measurements and explore new decay channels that could reveal physics beyond the current paradigm.
Joachim Mnich, CERN’s director of research, welcomed the discovery and highlighted its value as a tool for exploring cosmic origins. The LHC, once again, demonstrates its ability to generate data that challenge our ideas about the fundamental laws governing the universe.
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Source and photo: CERN
