Lightest meson (m ≈ 140 MeV). Three charge states: π⁺ (ud̄), π⁻ (ūd), π⁰ (uū / dd̄ mixture). Mediator of the residual strong nuclear force that binds protons and neutrons in nuclei (Yukawa, 1935). Charged pions decay weakly (π⁺ → μ⁺ν_μ, τ…
Lightest meson (m ≈ 140 MeV). Three charge states: π⁺ (ud̄), π⁻ (ūd), π⁰ (uū / dd̄ mixture). Mediator of the residual strong nuclear force that binds protons and neutrons in nuclei (Yukawa, 1935). Charged pions decay weakly (π⁺ → μ⁺ν_μ, τ…