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Axial Vector Current and Induced Pseudoscalar Coupling Constant on $μ^- p \to n ν_μ γ$ reaction

Il-Tong Cheon·Myung KI Cheoun
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Abstract

The 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 axial vector current on the gauge theory, 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, which is self gauge invariant, plays a key role in restoring the reliability of $g_P (- 0.88 m_μ^2) = 6.77 g_A (0)$. Comparison with conventional approaches is also presented.

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Il-Tong Cheon, Myung KI Cheoun. 1999-06-14. Axial Vector Current and Induced Pseudoscalar Coupling Constant on $μ^- p \to n ν_μ γ$ reaction. https://arxiv.org/abs/nucl-th/9906035

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