Interpretation of weak and electromagnetic processes in 12C in the particle-hole model

Reasons for the success of the particle-hole approach adopted by O'Connell, Donnelly, and Walecka in the unified interpretation of the semileptonic weak and eletromagnetic processes in the A=12 nuclear system will be examined. The example of the analyses of 0⁺₀ ↔ 1⁺₁ transitions in the context of the particle-hole model (PHM) and the intermediate-coupling model (ICM) brings to light two facts: (1) the nuclear matrix elements relevant to the 0⁺₀ ↔ 1⁺₁ transitions do not scale in a unique fashion from the PHM to the ICM; (2) the 0⁺₀ ↔ 1⁺₁ processes at low momentum transfer are overwhelmingly dominated by the Gamow–Teller matrix element. The dominance of a set of processes by one nuclear transition operator is the key to the success of the one-parameter scaling of the particle-hole amplitudes used by O'Connell, Donnelly, and Walecka.