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LHCb Detects First CP Violation in Baryon Decays

The measurement confirms Standard Model expectations; its small asymmetry cannot account for cosmic matter dominance, prompting plans to expand the dataset thirtyfold.

Overview

  • LHCb is the first experiment to observe CP violation in baryon decays by comparing Λb and anti-Λb particles.
  • Analysis of nearly nine years of data, encompassing almost one trillion beauty-lambda baryon decays collected between 2011 and 2018, underpins the finding.
  • Researchers measured a 2.5 percent decay-rate difference with 5.2σ significance, making a statistical fluctuation exceedingly unlikely.
  • Although the magnitude aligns with Standard Model predictions, it remains too small to explain why matter prevailed over antimatter after the Big Bang.
  • The collaboration intends to increase its dataset roughly thirtyfold in upcoming LHC runs to probe rarer decay channels and search for new sources of CP violation.