New horizon in particle physics: first observation of CP violation in baryon decays

2025/04/21 by Yu, Fu-Sheng, Lü, Cai-Dian · 2 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2504.15008

Abstract

Recently, the LHCb Collaboration achieved the observation of CP violation (CPV) in baryon decays through the process of Λ_b⁰→ pK^-π⁺π^-, reporting an asymmetry of (2.45±0.46±0.10)% with a significance of 5.2σ. This marks a breakthrough and a milestone in particle physics, six decades after the first observation of CPV in mesons. It will be helpful to understand the matter-antimatter asymmetry in the universe. In addition to the global CPV, local CPV is also observed by LHCb in the low mass region of m_pπ⁺π^-<2.7GeV as (5.4±0.9±0.1)% with a significance of 6.0σ. Intriguingly, this measurement aligns well with a theoretical prediction of (5.6-5.9)% based on a CPV dynamics using the data of Nπ→ pπ⁺π^- scatterings. Since baryons contain one more quark than mesons, the dynamics of baryon decays are significantly different from those of mesons. Therefore, the first observation of baryon CPV by LHCb opens a new horizon in the studies of dynamics of the strong interaction.

Citations

• Observation of charge-parity symmetry breaking in baryon decays
• Final-state rescattering mechanism in bottom-baryon decays
• CP violation observables in baryon decays
• Establishing CP Violation in b-Baryon Decays
• Large CP violation in charmed baryon decays
• Complementary CP violation induced by T-odd and T-even correlations
• A novel strategy for searching for C P violations in the baryon sector
• Charmless two-body antitriplet b-baryon decays
• Measurement of matter–antimatter differences in beauty baryon decays
• Factorization of heavy-to-light baryonic transitions in SCET
• Observation of Large CP Violation in the Neutral B Meson System
• Observation of CP violation in the B⁰ meson system
• Review of Particle Physics
• Experimental Tests of Factorization in Charmless Non-Leptonic Two-Body B Decays
• CP-Violation in the Renormalizable Theory of Weak Interaction
• Observation of C P violation in charm decays

Cited by

• Weak decays of singly heavy baryons: the 1/2→3/2 case

Related

• Observation of charge-parity symmetry breaking in baryon decays
• Establishing CP Violation in b-Baryon Decays
• First evidence of CP violation in beauty baryon to charmonium decays
• Source of CP Violation for the Baryon Asymmetry of the Universe
• CP violation and cosmology