We have observed a clear peak below the Σ+ -production threshold in the 4He(k−, π−) reaction at 600MeV/c and θKπ = 4°. This is confirmation of the existence of the bound state of 4ΣHe, which was reported in the 4He(stopped k−, π−) reaction. As in the case of stopped kaons, no such peak was found in the 4He(k−, π−) spectrum. Quantitatively reliable parameters for this level have been established. The binding energy and the width of the bound state are 4.4±0.3(stat)±1(syst) MeV and 7.0±0.7(stat)−0.0+1.2(syst) MeV, respectively.
ASJC Scopus subject areas
- Physics and Astronomy(all)