Structure of beta-decay strength function Sβ(E) and quenching of axial-vector weak interaction constant in halo nuclei

Resonance structure of the beta decay strength function S_β (E) for GT β^--decay of halo nuclei ⁶He and ¹¹Li is analyzed. Compare experimental total strength for β-transitions in gv²/4π units with the Ikeda sum rule (in (g_A^eff)²/4π units) one can determine the squared ratio of axial-vector and vector weak interaction constants value (g ^eff/g_V)². We obtained (g ^eff/gv)¹ = 1.272 ± 0.010 for ⁶He and (g_A^eff/gv)² = 1.5±0.2 for ¹¹Li β^--decays. Quenching of the weak axial-vector constant g_A^eff in halo nuclei is discussed. Analysis of the evolution of E_GTR - E_IAS toward neutron-rich nuclei was done. It is shown that the value Z/N ≈ 0.6 corresponds to the SU(4) Wigner's spin-isospin symmetry region.