Spectroscopic study of a possible Λnn resonance and a pair of ΣNN states using the (e, e′ K+) reaction with a tritium target

A mass spectroscopy experiment with a pair of nearly identical high-resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the (e, e' K+) reaction, enhancements, which may correspond to a possible Lambda nn resonance and a pair of Sigma NN states, were observed with an energy resolution of about 1.21 MeV (sigma), although greater statistics are needed to make definitive identifications. An experimentally measured Lambda nn state may provide a unique constraint in determining the Lambda n interaction, for which no scattering data exist. In addition, although bound A = 3 and 4 Sigma hypernuclei have been predicted, only an A = 4 Sigma hypernucleus (He-4(Sigma)) was found, utilizing the (K-, pi(-)) reaction on a He-4 target. The possible bound Sigma NN state is likely a Sigma(0)nn state, although this has to be confirmed by future experiments.

Automated summary

A mass spectroscopy experiment was performed at Jefferson Lab, observing possible Lambda nn and Sigma NN states. Further statistical data is needed for definitive identification. The experimentally measured Lambda nn state may provide important information about the Lambda n interaction. Additionally, a A=4 Sigma hypernucleus was found, but the existence of a A=3 Sigma hypernucleus needs confirmation from future experiments.