Scientists have published a paper in Nature about a discovery in particle physics. The paper describes the first clear observation of charge-parity symmetry breaking in the decays of baryons.
Charge-parity (CP) symmetry is a rule in physics that says matter and antimatter should act like mirror images of each other. Breaking this symmetry means matter and antimatter behave differently in some processes. Baryons are particles made up of three quarks, such as protons and neutrons that form the cores of atoms.
The LHCb experiment at CERN, which focuses on certain types of particles, analyzed a large amount of data from collisions between 2009 and 2018. The scientists looked at a specific baryon and watched how this baryon decays into lighter particles. They compared this to the decay of the antimatter version of the same baryon.
The results showed a small but clear difference in the decay rates between the matter and antimatter versions, about 2.45 percent off from perfect symmetry, with strong statistical proof. This is the first time such asymmetry has been seen in baryons, though it was found earlier in mesons, which are particles made of a quark and an antiquark pair.
Unknown physics beyond the standard model
Before this, experiments only saw hints of CP violation in baryons because the effect is tiny and needs lots of data to detect. The Large Hadron Collider (LHC) produced enough data.
CP violation helps explain why the universe has more matter than antimatter after the Big Bang. The standard model, the main theory of particles and forces, predicts some CP violation but not enough to match the observed imbalance in the cosmos. This suggests there may be unknown physics beyond the standard model.
The finding opens new paths to test theories and search for extra sources of asymmetry. Precise measurements like this could reveal flaws in current ideas or point to new particles. A CERN press release (first issued in March before the publication of the paper on July 16) praises the result as a tool to explore the matter-antimatter puzzle further, with ongoing work at the collider and plans for future machines.