标题： 关于$^{22}$铝中质子晕的存在 显示英文标题

标题： On the existence of a proton halo in $^{22}$Al

摘要： 近年来，在实验中越来越多的晕核或候选核被识别或提出。 宣布了 $^{22}$Al 的晕结构通过 $^{22}$Si/$^{22}$O 镜像 Gamow-Teller 跃迁中的大同位旋不对称性得到揭示 [Phys. Rev. Lett. 125, 192503 (2020)]。 我们强调，在可能的未结合核 $^{22}$Si 和双幻数核 $^{22}$O 的波函数之间已经存在显著的镜像不对称性，这很大程度上解释了跃迁中观察到的不对称性。 此外，这些跃迁仅涉及子核 $^{22}$Al 和 $^{22}$F 的 $1^+$激发态。由于 $^{22}$Al 的 $1^+$态具有质子不束缚的特性，不能将其视为晕态。 自旋宇称分析表明，在基态 $^{22}$Al 中，一个弱束缚的 $2s_{1/2}$价质子是不太可能的。 To investigate the shell structure for the ground state of $^{22}$Al, we employ the state-of-the-art deformed and triaxial relativistic Hartree-Bogoliubov theories in continuum. We find that a small $s$-wave component of $5\%$ appears for the weakly bound valence proton in $^{22}$Al only when triaxial deformation is considered. While the examination of densities and rms radii indicates that this small $s$-wave component is insufficient to form a discernible proton halo in $^{22}$Al, slightly larger $2s_{1/2}$ occupations have been reported in other recent theoretical results. 如何许多低-$\ell$成分足以在库仑势垒存在的情况下形成质子晕仍然是一个开放问题。 因此，未来对反应或相互作用截面以及破裂碎片动量分布的测量是非常期望的，以验证$^{22}$铝是否是晕核。 显示英文摘要

摘要： More and more halo nuclei or candidates have been identified or suggested in experiments in recent years. It was declared that the halo structure of $^{22}$Al is revealed by the large isospin asymmetry in $^{22}$Si/$^{22}$O mirror Gamow-Teller transitions [Phys. Rev. Lett. 125, 192503 (2020)]. We highlight that a significant mirror asymmetry already exists between wave functions of the likely unbound nucleus $^{22}$Si and the doubly-magic nucleus $^{22}$O, which largely explains the observed asymmetry in the transitions. Furthermore, these transitions involve only the $1^+$ excited states of the daughter nuclei $^{22}$Al and $^{22}$F. The $1^+$ state of $^{22}$Al cannot be considered a halo state due to its proton-unbound nature. An analysis of the spin-parity suggests that a weakly bound $2s_{1/2}$ valence proton in the ground-state $^{22}$Al is improbable. To investigate the shell structure for the ground state of $^{22}$Al, we employ the state-of-the-art deformed and triaxial relativistic Hartree-Bogoliubov theories in continuum. We find that a small $s$-wave component of $5\%$ appears for the weakly bound valence proton in $^{22}$Al only when triaxial deformation is considered. While the examination of densities and rms radii indicates that this small $s$-wave component is insufficient to form a discernible proton halo in $^{22}$Al, slightly larger $2s_{1/2}$ occupations have been reported in other recent theoretical results. The question of how many low-$\ell$ components are sufficient to form a proton halo in the presence of the Coulomb barrier remains open. Thus, future measurements of reaction or interaction cross sections and momentum distributions of breakup fragments are highly desirable to verify whether $^{22}$Al is a halo nucleus.