Configuration of the two-neutron halo ofLi11and Gamow-Teller transition

Effects of the halo as well as meson exchange currents (MEC) are studied for the Gamow-Teller (GT) β transition ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$(3/$2^{\mathrm{-}}$)${\to }^{11}$Be(1/$2^{\mathrm{-}}$,0.32 MeV). They are found to be important to reduce transition matrix elements and remedy deviations from the observed logft value of the GT transition. This GT transition is shown to play an indispensable role in identifying the structure of two-neutron halo of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$. It is indicated that the two neutrons forming the halo consist of the ${\mathit{p}}_{1/2}^2$ configuration with 60–70 % probability.