Continuum Lambda spectra for a 6Li_Lambda hypernucleus in the 6Li(K-, pi-) reaction

Abstract

We theoretically investigate Lambda production via a (K-, pi-) reaction on a 6Li target, using the distorted-wave impulse approximation (DWIA) with a Fermi-averaged K-n --> pi-Lambda amplitude. We calculate Lambda production spectra using the Green's function method for a 5Li nuclear core + Lambda system, employing a Lambda folding-model potential based on the 5Li nuclear density, which is constructed from alpha-p and 3He-d cluster wave functions. The results show that the calculated spectrum, which includes Lambda bound, resonance, and continuum states, agrees well with the experimental data from the (K-, pi-) reaction at p_K- = 790 MeV/c (0 deg.), where substitutional (0p_Lambda, 0p^{-1}_n) and (0s_Lambda, 0s^{-1}_n) configurations dominate in the near-recoilless reactions. A narrow peak corresponds to a high-lying excited state with spin-parity J^P= 1+ at E_Lambda= 13.8 MeV near the 3He + d + Lambda threshold, arising from interference effects between 5Li(3/2+)x(0s1/2)_Lambda and 5Li(1/2+)x(0s1/2)_Lambda components. This study offers a valuable framework for extracting essential information on the structure and production mechanisms of hypernuclear states from experimental data.