Pair counting, pion-exchange forces and the structure of light nuclei
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
A simple but useful guide for understanding the structure of light nuclei is presented. It is based on counting the number of interacting pairs in different spin-isospin (S,T) states for a given spatial symmetry and estimating the overall binding according to the sum of {sigma}{sub i}{center_dot}{sigma}{sub j}{tau}{sub i}{center_dot}{tau}{sub j} expectation values, as suggested by one-pion exchange. Applied to s- and p-shell nuclei, this simple picture accounts for the relative stability of nuclei as A increases and as T changes across isobars, the saturation of nuclear binding in the p shell, and the tendency to form d,t, or {alpha} subclusters there. With allowance for pairwise tensor and spin-orbit forces, which are also generated or boosted by pion exchange, the model explains why mixing of different spatial symmetries in ground states increases as T increases across isobars and why, for states of the same spatial symmetry, the ones with greater S are lower in the spectrum. The ordering of some sd-shell intruder levels can also be understood. The success of this simple model supports the idea that one-pion exchange is the dominant force controlling the structure of light nuclei.
- OSTI ID:
- 20771340
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 73, Issue 3; Other Information: DOI: 10.1103/PhysRevC.73.034317; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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