$\bar{K}$Ndynamics at and near threshold energies

A Cieplý,J Smejkal

doi:10.1051/epjconf/20100303015

Abstract

We have constructed eﬀective separable meson-baryon potentials to match the equivalent chiral amplitudes up to the second order in external meson momenta. The parameters of the model were ﬁtted to the threshold and low energy K − p data including the 1s level characteristics of the kaonic hydrogen atom. We discuss the results of our ﬁts and use the model to calculate the πΣ mass spectrum and the energy dependence of the K − N amplitudes.

Highlights

The meson-baryon interactions at low energies have become a testing ground for theoretical models based on chiral symmetry
The origin and structure of the Λ(1405) resonance observed in the πΣ mass spectrum are an actively pursued topic
The interest in the πΣ mass distribution has arisen since discovering that the chiral meson-baryon dynamics generates two poles in the complex energy plane that can be related to the Λ(1405) resonance

Summary

Introduction

The meson-baryon interactions at low energies have become a testing ground for theoretical models based on chiral symmetry. Unlike the pion-nucleon interaction the K N dynamics is strongly influenced by the existence of the Λ(1405) resonance, just below the K− p threshold. This means that the standard chiral perturbation series do not converge. One can use nonperturbative coupled channel techniques to deal with the problem and generate the Λ(1405) resonance dynamically. Though such approach violates the crossing symmetry it has proven quite useful and several authors have already applied it to various low energy meson-baryon processes [1]-[6]. A more detailed account of our work was given in Refs. [9] and [10] and here we concentrate only on the main results

Separable potentials

Mj 2E j ωj

K N data fit

Concluding remarks