2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/83034The recent TRIUMF experiment for $μ^- p \to n ν_μ γ$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $μ^- p \to n ν_μ$ experiment as much as 44 %. Reexamining contribution of the axial vector current, we found an additional term to the matrix element of Beder and Fearing which was used to extract the $g_P$ value from the measured photon energy spectrum. This additional term plays a key role to restore the reliability of $g_P (- 0.88 m_μ^2) = 6.77 g_A (0)$.11 pages, 2 figuresNuclear Theorytext