Related papers: What We Know About the Lambda(1405)
In this talk a brief review of several problems involving systems with strangeness is made. In the first place one shows how the $\Lambda (1405)$, $\Lambda(1670)$ and $\Sigma(1620)$ states, for $S = -1$, and the $\Xi(1620)$ for $S= -2$ are…
The nature of the Lambda(1405), and its place in the baryon spectrum has remained uncertain for decades. Theoretical studies have shown that it may possess strong dynamical components which are not seen in other well-known baryons. Using…
The $\Lambda(1520)$ resonance is generated dynamically in a unitary coupled channel framework with the $\pi\Sigma^*$ and $K\Xi^*$ channels in s-wave and $\pi\Sigma$ and $\bar K N$ channels in d-wave. The dynamics of this resonance close to…
A new unitarization approach is discussed and applied to study the elastic $\pi K$ scattering process. The existence of the light $\kappa$ resonance is firmly established if the scattering length in the I=1/2 channel does not deviate too…
We report on the latests developments in the field of baryonic resonances generated from the meson-baryon interaction in coupled channels using a chiral unitary approach. The collection of resonances found in different strangeness and…
We examine the role of the $\Lambda(1405)$ in kaon-nucleon scattering lengths using chiral perturbation theory. The leading nonanalytic SU(3) corrections reduce the coupling of the $\Lambda (1405)$ to $KN$ compared to $\Sigma\pi$. S-wave…
We investigate the pentaquark system $qqqs \bar q$ in a framework of chiral quark model. Two structures, $(qqq)(s\bar{q})$ and $(qqs)(q\bar{q})$, with all possible color, spin, flavor configurations are considered. The calculations show…
We formulated the Lambda(1405) (abbreviated as Lambda^*) --> (Sigma pi)^0 invariant-mass spectra produced in p+p --> p + Lambda^* + K^+ reactions, in which both the incident channel for a quasi-bound K^-p state and its decay process to…
We study the coupling of the Lambda(1520)= Lambda* resonance to the \bar K* vector meson and nucleon. This coupling is not directly measured from the resonance decay, but is expected to be important in hyperon production reactions, in…
The pole structure of the $\Lambda(1405)$ has been a topic of debate for a long time. Chiral perturbation theory predicts that its experimental spectrum may be explained by a two pole structure originating in the $SU(3)$ chiral dynamics of…
In this talk I summarize a recently proposed mechanism to understand pi pi scattering to 1 GeV. The model is motivated by the 1/Nc expansion to QCD, and includes a current algebra contact term and resonant pole exchanges. Chiral symmetry…
The $K^{-}$ induced production of $\Lambda(1405)$ in the $K^{-} d \to \pi \Sigma n$ reaction is investigated having in mind the conditions of the DAFNE facility at Frascati. We find that the fastest kaons from the decay of the $\phi$ at…
The $K^- p \to \pi^0 \pi^0 \Sigma^0$ reaction is studied within a chiral unitary model. The distribution of $\pi^0 \Sigma^0$ states forming the $\Lambda(1405)$ shows, in agreement with a recent experiment, a peak at 1420 MeV and a…
We report on the first results of a full three-body calculation of the $\bar{K}NN$-$\pi YN$ amplitude for the $K^-d\rightarrow\pi\Sigma n$ reaction, and examine how the $\Lambda(1405)$ resonance manifests itself in the neutron energy…
The $SU(3)$ chiral effective lagrangian at next-to-leading order is applied to the S-wave meson-baryon interaction in the energy range around the $\eta N$ threshold. Potentials are derived from this lagrangian and used in a coupled channel…
We review recent progress in our understanding of the nucleon excitation spectrum. Thanks to dedicated efforts at facilities such as ELSA, MAMI and Jefferson Lab, several new nucleon resonances have been discovered, and evidence for…
We investigate the interaction of an antikaon ($K^-$) with the $^{6}$Li nucleus, described as an $\alpha + d$ cluster system. The study aims to explore the formation of the $\Lambda(1405)$ resonance through the $K^-d$ subsystem in the…
We set up a general framework to describe $\pi\pi$ scattering below 1 GeV based on chiral low-energy expansion with possible spin-0 and 1 resonances. Partial wave amplitudes are obtained with the $N/D$ method, which satisfy unitarity,…
We have investigated the $\Lambda_c^+\to n\pi^+\pi^0$ decay process using the chiral unitary approach, by considering that the nucleon resonance $N(1535)$ could be dynamically generated through $S$-wave pseudoscalar meson-octet baryon…
The capture of K$^-$ mesons on nucleons bound in nuclei offer a chance to study the $\Sigma \pi$ pairs below the kinematic threshold of the $\bar{\mathrm{K}}$N systems. Various hyperon-pion charged combination are presently under…