2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/191619We establish the bridge between the commonly used Nabetani-Ogaito-Sato-Kishimoto (NOSK) formula for the asymmetry parameter $a_Λ$ in the $\vecΛp \to np$ emission of polarized hypernuclei, and the shell model (SM) formalism for finite hypernuclei. We demonstrate that the s-wave approximation leads to a SM formula for $a_Λ$ that is as simple as the NOSK one, and that reproduces the exact results for $^5_Λ$He and $^{12}_Λ$C better than initially expected. The simplicity achieved here is indeed remarkable. The new formalism makes the theoretical evaluation of $a_Λ$ more transparent, and explains clearly why the one-meson exchange model is unable to account for the experimental data of $^5_Λ$He.9 pages. to be published in Physical Review CNuclear Theorytext