Breakthrough at CERN: First Confirmed CP Violation in Baryons Offers Clues to Universe’s Origins

In a groundbreaking discovery that could reshape our understanding of the universe’s very existence, physicists at the Large Hadron Collider (LHC) near Geneva have observed a new form of charge-parity (CP) violation—this time in a class of particles known as baryons.

For decades, scientists have been grappling with one of the most fundamental mysteries in physics: Why does the universe exist predominantly of matter and not equal parts matter and antimatter? According to current theories, the Big Bang should have produced matter and antimatter in equal quantities, which should have annihilated each other completely. Yet, somehow, matter won out—and CP violation is believed to be a key reason why.

Until now, CP violation had been confirmed only in mesons, particles made of one quark and one antiquark. But the LHCb collaboration has, for the first time, confirmed CP violation in baryons, particles made of three quarks—like protons and neutrons.

The researchers focused on a specific baryon known as the lambda-b baryon, observing its decay into a proton, a kaon, and two pions. Their analysis showed that the rate of decay differed slightly from that of its antimatter counterpart, signaling a violation of CP symmetry. This asymmetry, though subtle, crossed the critical five-sigma threshold required for a confirmed discovery.

The findings, presented on March 25 at the Rencontres de Moriond conference in La Thuile, Italy, and detailed in a paper submitted to arXiv.org, build upon earlier hints of CP violation in baryons.

While the discovery does not fully explain the matter-antimatter imbalance in the universe, it marks a major step forward. Physicists now have a new frontier to explore in their quest to understand the mechanisms that allowed matter to dominate—and thus, for the universe as we know it to exist.

With further research, this breakthrough could eventually lead to a deeper theory that unites the known and still-unknown laws of particle physics—and perhaps even answer the age-old question of why we are here at all.