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We briefly review the generalized Skyrmion model for the baryon recently suggested by us. It takes into account the tower of vector and axial mesons as well as the chiral symmetry breaking. The generalized Skyrmion model provides the qualitative explanation of the Ioffe's formula for the baryon mass. [ABSTRACT FROM AUTHOR]

We calculate the η′ amplitude at low energies considering chiral Lagrangians and η η′ mixing, the coupling of η′N to the victor-baryon channels and one Lagrangian allowed for singlet meson-baryon interaction. We obtain cross sections for elastic η′ scattering and transition of η′N to the open channels πN, ηN, η′N, KΛ and KΣ. [ABSTRACT FROM AUTHOR]

We analyze meson-baryon scattering lengths in the framework of covariant baryon chiral perturbation theory at leading one-loop order. We compute the complete set of matching relations between the dimension-two low-energy constants in the two- and three-flavor formulations of the theory. We derive new two-flavor low-energy theorems for pion-hyperon scattering that can be tested in lattice simulations. [ABSTRACT FROM AUTHOR]

We use chirally motivated effective meson-baryon potentials to describe the low energy KN data including the characteristics of kaonic hydrogen. Our results are examined in comparison with other approaches based on the unitarity and dispersion relation for the inverse of the T-matrix. We demonstrate that the movements of the poles generated by the model upon varying the model parameters can serve as a tool to get additional insights on the dynamics of the strongly coupled πΣ-KN system. [ABSTRACT FROM AUTHOR]

After referring to some basic features of chiral models for baryons, with quarks and mesons, we describe how to construct model states representing physical baryons. We consider soliton models such as the Linear Sigma Model or the Chromodielectric Model, and bag models such as the Cloudy Bag Model. These models are solved approximately using variational approaches whose starting point is a mean-field description. We go beyond the mean-field description by introducing quantum fluctuations in the mesonic degrees of freedom. This is achieved, in a first step, by using a quantum state to represent meson clouds and, secondly, by performing an angular momentum and isospin projection from the mean-field state (actually a coherent state). Model states for baryons (nucleon, Delta, Roper) constructed in this way are used to determine several physical properties. I this seminar we paid a particular attention to the nucleon-delta electromagnetic and weak transition, presenting the model predictions for the electromagnetic and axial amplitudes. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Meson-Baryon Interactions can be successfully described using both Chiral Symmetry and Unitarity. The s--wave meson-baryon scattering amplitude is analyzed in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry in the potential. Two body coupled channel unitarity is exactly preserved. The needed two particle irreducible matrix amplitude is taken from lowest order Chiral Perturbation Theory in a relativistic formalism. Off-shell behavior is parameterized in terms of low energy constants. The relation to the heavy baryon limit is discussed. The position of the complex poles in the second Riemann sheet of the scattering amplitude determine masses and widths baryonic resonances of the N(1535), N(1670), Λ(1405) and Λ(1670) resonances which compare well with accepted numbers. [ABSTRACT FROM AUTHOR]

The internal structure of the resonant Λ(1405) state is investigated based on meson-baryon coupled-channels chiral dynamics, by evaluating density distributions obtained from the form factors of the Λ(1405) state. The form factors are extracted from current-coupled scattering amplitudes in which the current is coupled to the constituent hadrons inside Λ(1405). Using several probe interactions and channel decomposition, we find that the resonant Λ(1405) state is dominantly composed of widely spread K around N, with a small fraction of the escaping πΣ component. [ABSTRACT FROM AUTHOR]

The constituent quark number scaling of elliptic flow is studied in a non-equilibrium hadronization and freeze-out model with rapid dynamical transition from ideal, deconfined and chirally symmetric Quark Gluon Plasma, to final non-interacting hadrons. In this transition a Bag model of constituent quarks is considered, where the quarks gain constituent quark mass while the background Bag-field breaks up and vanishes. The constituent quarks then recombine into simplified hadron states, while chemical, thermal and flow equilibrium break down one after the other. In this scenario the resulting temperatures and flow velocities of baryons and mesons are different. Using a simplified few source model of the elliptic flow, we are able to reproduce the constituent quark number scaling, with assumptions on the details of the non-equilibrium processes. [ABSTRACT FROM AUTHOR]

Using a chiral unitary approach for meson-baryon scattering in the strangeness zero sector, where the N*(1535) and Δ*(1700) resonances are dynamically generated, we study the reactions γp → π0ηp and γp → π0K0Σ+ at photon energies at which the final states are produced close to threshold. Among several reaction mechanisms, we find the most important is the excitation of the Δ*(1700) state which subsequently decays into a pseudoscalar meson and the N*(1535). Hence, the reaction provides useful information with which to test current theories of the dynamical generation of the low-lying 1/2- and 3/2- states. Predictions are made for cross sections and invariant mass distributions which can be compared with forthcoming experiments at ELSA. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]