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

TL;DR

This paper presents a theoretical study of Lambda hypernucleus production in 6Li via a (K-, pi-) reaction, using advanced models to match experimental spectra and identify hypernuclear states.

Contribution

It introduces a comprehensive theoretical framework combining DWIA and Green's function methods to analyze hypernuclear spectra in 6Li, providing insights into structure and production mechanisms.

Findings

Calculated spectra agree well with experimental data.

Identified a high-lying excited state at 13.8 MeV with J^P= 1+.

Revealed interference effects influencing hypernuclear state features.

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.