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arXiv · 2601.16551

Analysis of $M1$ capture in the $\alpha(d,\gamma)^6$Li reaction

Ergash M. Tursunov·Daniel Baye
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Abstract

An effective operator is exactly equivalent to the long-wavelength form of the $M1$ operator in transition matrix elements. It allows us to analytically and numerically analyze the $M1$ contribution to the $\alpha(d,\gamma)^6$Li reaction. Isoscalar $M1$ transitions from an initial $S$ wave are shown to be forbidden in radiative capture reactions when distortion is neglected in the initial state. A calculation in a three-body model with proton, neutron, and a structureless $\alpha$ interacting through effective forces leads to a negligible $M1$ $S$-factor at small energies. The dominant $M1$ contribution comes from transitions from an initial $S$ wave to isospin 1 components of the $^6$Li ground state. It is suggested that using this effective $M1$ operator in other models should clarify the origin of large discrepancies between $M1$ $S$-factors appearing in the literature.

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Ergash M. Tursunov, Daniel Baye. 2026-01-23. Analysis of $M1$ capture in the $\alpha(d,\gamma)^6$Li reaction. https://doi.org/10.1103/lp1x-blc9

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