Variational calculations for K-few-nucleon systems

TL;DR

This paper investigates deeply bound states of K-few-nucleon systems using variational and Schrödinger equation methods, highlighting the dominant attraction from Lambda(1405) and Sigma(1385) states, with binding energies ranging from 40 to 220 MeV.

Contribution

It provides a detailed calculation of K-few-nucleon bound states considering the effects of Lambda(1405) and Sigma(1385), including the formation of new quasi-bound states.

Findings

Binding energies range from 40 to 220 MeV.

Sigma(1385) contributes significantly to binding and state formation.

Uncertainties due to unknown KN interactions in the subthreshold region.

Abstract

Deeply bound KNN, KNNN and KNNNN states are discussed. The effective force exerted by the K meson on the nucleons is calculated with static nucleons. Next the binding energies are obtained by solving the Schrodinger equation or by variational calculations. The dominant attraction comes from the S-wave Lambda(1405) and an additional contribution is due to Sigma(1385). The latter state is formed at the nuclear peripheries and absorbs a sizable piece of the binding energy. It also generates new branches of quasi-bound states. The lowest binding energies based on a phenomenological KN input fall into the 40-80 MeV range for KNN, 90-150 MeV for KNNN and 120-220 MeV for K-alpha systems. The uncertainties are due to unknown KN interactions in the distant subthreshold energy region.