Soft giant resonance in two neutron halo nucleus ¹¹Li

Lithium-11 is a showcase of neutron halos and has been providing new insight to nuclear structure researches. Recently, an isoscalar resonance at low excitation energy (E_x∼ 1 MeV) has been confirmed by the development of a low-energy high-intensity beam of ¹¹Li at TRIUMF. By inelastic scattering measurements (p , p) and (d , d) with inverse kinematics, the first excited state of ¹¹Li has been studied in detail and an isoscalar nature of the transitions has been confirmed and a strong transition amplitude has been observed indicating the soft-resonance of ¹¹Li. Those recent experimental results on the excitation of the soft resonance are described and then recent theoretical developments based on the four-body continuum-discretized coupled-channels ¹¹Li + p system are presented together with a brief history of the resonance search in ¹¹Li.