AI 中文总结
该研究通过质量分解发现，张量力驱动的奇Z/奇N质量交错导致奇A最低质量同量异位素序列跳过Tc和Pm，解释了二者缺失稳定同位素的谜题。
AI 中文摘要
锝（Tc）和钷（Pm）是铋元素范围内唯一缺乏稳定同位素的元素，这是物理学和化学领域长期存在的谜题。我们将这种缺失视为在质量数A为奇数的β稳定同量异位素链中选择最低质量整数质子数Z的问题。三点质量抛物线识别出局部最小值的两单位跳变，而五点分解将平滑二次分量与奇Z/奇N质量交错分离，此处定义为奇Z同量异位素相对于相邻奇N同量异位素的质量偏移。通过该分解，拟合的体-壳质量模型可重现平滑趋势及幻数附近由壳层驱动的弯曲，包括常规壳层闭合跳变。然而，该模型未包含奇Z/奇N交错，无法解释Tc和Pm的跳变。分离出的奇Z/奇N交错在Tc和Pm区域始终为正，且数值足够大，使得最低质量整数Z序列跳过Tc和Pm。壳模型占据分析表明，这种区域交错反映了质子-中子相互作用中依赖轨道的张量力单极效应。我们确定张量力驱动的奇Z/奇N质量交错是奇A最低质量同量异位素序列中Tc和Pm跳变的起源。
英文摘要
Technetium (Tc) and promethium (Pm) are the only elements that lack stable isotopes in the range up to bismuth, a long-standing puzzle in physics and chemistry. We treat this absence as a problem of selecting the lowest-mass integer proton number Z in beta-stable isobaric chains with odd mass number A. Three-point mass parabolas identify two-unit jumps in the local minimum, whereas a five-point decomposition separates the smooth quadratic component from odd-Z/odd-N mass staggering, defined here as the mass shift of odd-Z isobars relative to neighboring odd-N isobars. With this decomposition, a fitted bulk-plus-shell mass model reproduces the smooth trend and shell-driven bending near magic numbers, including conventional shell-closure skips. This model, however, does not include odd-Z/odd-N staggering and cannot account for the Tc and Pm skips. The separated odd-Z/odd-N staggering remains positive across the Tc and Pm regions and is large enough for the lowest-mass integer-Z sequence to skip Tc and Pm. Shell-model occupation analysis suggests that this regional staggering reflects an orbital-dependent tensor-force monopole effect in the proton-neutron interaction. We identify tensor-force-driven odd-Z/odd-N mass staggering as the origin of the Tc and Pm skips in the odd-A sequence of lowest-mass isobars.
Comments20 pages, 4 figures, 2 extended data figures and 2 extended data tables
