CP violation, a phenomenon where the behavior of matter differs from that of antimatter, has long been observed in certain particles called mesons. However, its presence in baryons, such as protons and neutrons, was unknown until now. A recent study published in Nature by the LHCb collaboration has reported the first-ever observation of CP violation in baryon decays.
The discovery is significant because it sheds light on why matter dominates the universe over antimatter. Scientists believe that after the Big Bang, both matter and antimatter existed in equal amounts. However, some processes, such as CP violation, could have created an imbalance between them.
Researchers used data from the Large Hadron Collider to study the decay of a specific baryon called the Λb⁰ baryon into various particles, including protons and kaons. By analyzing these decays, they found a significant difference in the rates between the matter and antimatter counterparts, with an asymmetry of about 2.45%.
This result is well above the statistical threshold required for physicists to claim a discovery, indicating that the findings are unlikely to be due to chance or experimental errors. The observation also matches predictions made by the Standard Model, but the amount of CP violation in this case is not enough to explain the observed matter-antimatter imbalance.
The study’s findings open up new avenues for searching for “new physics,” which could reveal new effects or particles beyond what is predicted by current theories. To fully understand the matter-antimatter asymmetry, researchers need to determine the complex phase associated with CP violation in baryons and compare it to predictions made by the Standard Model.
While this discovery is a significant step forward, resolving the mystery of the universe’s missing antimatter will require both experimental and theoretical progress. The observation of CP violation in baryons highlights the importance of continued research into these fundamental aspects of physics.
Source: https://www.thehindu.com/sci-tech/science/cern-collider-reveals-major-clue-to-universes-bias-against-antimatter/article69817740.ece