Equation 15 · Part 3 · The Valley of Stability Is a Fitness Landscape
Symbol Z
What this part means
the mass number.
Its job in the formula
Z is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol Z→Article meaning
Where the article explains it
Binding energy per nucleon is the landscape’s fitness function The quantity that plays fitness’s role has a name in nuclear physics already: binding energy per nucleon, B(A,Z)/A , where A = N + Z is the mass number.
The passage around this formula
…area, because nucleons at the boundary have fewer neighbors to bind to — a tax on being exposed at the edge of the configuration, heaviest for small A where the surface-to-volume ratio is largest. The Coulomb term, - Z(Z-1)/ , is a pure liability: mutually repelling protons cost binding energy in proportion to roughly , which is why the landscape eventually tilts against very proton-heavy states no matter how favorable the other terms are. The asymmetry term, - (A-2Z)^2/A , penalizes any departure…
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Sources cited in the article section
- [11] Zur Theorie der Kernmassen ↗
- [13] The atomic nuclide with the highest mean binding energy ↗
- [1] The AME 2020 atomic mass evaluation (I). Evaluation of input data, and adjustment procedures ↗
These citations provide research context; check each source for the exact claim it supports.