Matter-Antimatter Asymmetry

CP violation, kaon oscillations, and why the universe is made of matter

CP violation ε ε = 2.2×10⁻³
K⁰ mixing Δm Δm = 15
B meson mode K⁰ system
2.2×10⁻³
|ε| (K system)
0.003
A_CP asymmetry
0.997
Γ(K→ππ)/Γ̄
13.1°
CKM phase δ

About

CP violation — the asymmetry between matter and antimatter — was discovered in neutral kaon decays in 1964 (Nobel 1980, Cronin and Fitch). In the Standard Model, CP violation arises from a single complex phase δ in the CKM quark mixing matrix. The K⁰ meson oscillates between K⁰ and K̄⁰ states, with the mass eigenstates K_L and K_S differing by the tiny parameter ε ≈ 2.2×10⁻³. However, the known CP violation is ~10¹⁰ times too small to explain the observed matter-antimatter asymmetry of the universe.