Weak isoscalar response of 11B

Weak-interaction responses of 11B were studied by measuring the 11B(3He, t) and 11B(p, p′) reactions. Obtained nuclear transition matrix elements B(GT), B(στ), and B(σ) were compared with the shell-model calculations. The shell-model calculations, which explained the isovector parts B(GT) and B(στ) reasonably well if the quenching factors of 0.5–0.7 were taken into account, did not describe the isoscalar part B(σ).