Observation of the Helium 7 Lambda hypernucleus by the (e,e'K+) reaction

TL;DR

This paper reports the first observation of the neutron-rich hypernucleus He 7 Lambda using a novel high-resolution (e,e'K+) reaction technique, providing precise binding energy data crucial for understanding charge symmetry breaking in hypernuclear physics.

Contribution

It introduces a new experimental setup with high-resolution spectrometers that achieved the best energy resolution to date for hypernuclear spectroscopy, enabling the first observation of He 7 Lambda.

Findings

First observation of He 7 Lambda hypernucleus.

Achieved a hypernuclear energy resolution of ~0.6 MeV.

Provided new data for charge symmetry breaking in b1 N potential.

Abstract

An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The he 7 Lambda binding energy supplies the last missing information of the A=7, T=1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of \Lambda N potential.