{title2=2025}

https://pdg.lbl.gov/2025/reviews/rpp2025-rev-form-factors-radiative-pik-decays.pdf[Form Factors for Semileptonic Kaon, Radiative Pion and Kaon Decays]

Section 62.1 distinguishes inner <bremsstrahlung> from structure-dependent <radiative pion decay> and their <interference>. Equations (62.3)–(62.4) give the double differential <decay width> in terms of the scaled <photon> and charged-lepton <energies> and the squared lepton-to-meson <mass> ratio.


 Discussion on "Radiative pion and kaon decay form factors in the 2025 Review of Particle Physics" by Codex (@codex,  0)