Role of vector and pseudoscalar mesons in understanding1/2−N*andΔresonances

Abstract

A study of nonstrange meson-baryon systems has been made with the idea of understanding the properties of the low-lying 1/2 − N * and ∆ resonances. The coupled channels are built by considering the pseudoscalar and vector mesons together with the octet baryons. The formalism is based on obtaining the interactions from the lowest order chiral Lagrangian when dealing with pseudoscalar mesons and relying on the hidden local symmetry in case of the vector mesons. The transition between the two systems is obtained by replacing the photon by a vector meson in the Kroll-Ruderman theorem for the photoproduction of pseudoscalar mesons. The subtraction constants, required to calculate the loop-function in the scattering equations, are constrained by fitting the available experimental data on some of the reactions with pseudoscalar meson-baryon final states. As a consequence, we find resonances which can be related to N * (1535), N * (1650) (with a double pole structure), N * (1895) and ∆(1620). We conclude that these resonances can be, at least partly, interpreted as dynamically generated resonances and that the vector mesons play an important role in determining the dynamical origin of the low-lying N * and ∆ states. a kanchan@if.usp.br

Study of theKN−K*Ncoupled system ins-wave

“…We would like to recall that efforts in this direction have been made earlier within different formalisms [10][11][12][14][15][16][17][18][19] showing that this coupling is important for reproducing experimental data. For example, it is crucial for calculating some properties of a resonance such as its partial decay widths for different channels.…”

“…The formalism was further extended to couple VB with pseudoscalar meson-baryon (PB) systems by extending the Kroll-Ruderman theorem for the pion photoproduction by replacing the photon by a vector meson in accordance with vector meson dominance. This formalism has been used to solve coupled-channel equations for strange and nonstrange meson-baryon systems [11,12], and has been found to be useful in reproducing some relevant experimental data and understanding the properties of several resonances.…”

“…[9][10][11][12] a detailed investigation of coupled light meson-baryon systems involving pseudoscalars and vector mesons was performed. The basic vector meson-baryon (VB) Lagrangian, used in Refs.…”

“…The motivation of the present paper is to make an attempt to revise the information available on the KN and K * N s-wave interactions from previous studies by using the more complete approach of Refs. [9][10][11][12] and by constraining the resulting amplitudes to fit the relevant available data.…”

“…The basic vector meson-baryon (VB) Lagrangian, used in Refs. [9][10][11][12], is based on the hidden local symmetry [13] which treats vector mesons consistently with the chiral symmetry. A study of VB systems done in Ref.…”