Topics on (e,e'K$^+$) spectroscopy of $\Lambda$ hypernuclei at JLab

Spectroscopic study of electro-produced $\Lambda$ hypernuclei started at Jefferson Lab in 2000. Though it was known that spectroscopy of electro-produced hypernuclei has many advantages over other meson-produced hypernuclear spectroscopy, there are many experimental difficulties such as small production cross-section, huge elecron background and so on.

After more than 15 years efforts by an international collaboration lead by Japan and US groups, the spectroscopy of $\Lambda$ hypernuclei has finally established by introducing novel experimental techniques. JLab hypernuclear collaboration is now preparing new experiments such as E12-15-008 (study of isospin dependence of $\Lambda$ hypernuclei) and E12-17-003 (study of $\Lambda$N interaction by study of $\Lambda$nn resonance).

I will overview unique features of spectroscopy of $\Lambda$ hypernuclei with electron beams and discuss future prospects. Current status of $\Lambda$nn resonance or bound state search experiment which will start very soon at JLab will be also reported.