Related papers: Higher and missing resonances in omega photoproduc…
An investigation of $\gamma p\to \omega p$ is presented in a constituent quark model approach. The sparse data in the large $t$ region where the resonances dominate is well described within the model, while the diffractive behavior in the…
We present an optimization scheme that employs a Genetic Algorithm (GA) to determine the properties of low-lying nucleon excitations within a realistic photo-pion production model based upon an effective Lagrangian. We show that with this…
The electromagnetic pion production reactions are investigated within the dynamical coupled-channels model developed in {\bf Physics Reports, 439, 193 (2007)}. The meson-baryon channels included in this study are $\gamma N$, $\pi N$, $\eta…
We study the operator description of the gluon spin contribution ($\Gamma$) to the nucleon's spin as it is measured in deep inelastic processes. $\Gamma$ can be related to the forward matrix element of a local gluon operator in $A^+=0$…
An existing single resonance model with S11, P11 and P13 Breit-Wiegner resonances in the s-channel has been re-applied to the old pi N --> K Lambda data. It has been shown that the standard set of resonant parameters fails to reproduce the…
The study of the $\gamma^* N\rightarrow \Delta$ reaction presents the best quantitative method to explore the deviation of hadron shapes from spherical symmetry (nonspherical amplitudes). Significant non-spherical electric (E2) and Coulomb…
We use the gauge/gravity correspondence to calculate the rate of photon production in a strongly coupled N=4 plasma in the presence of an intense magnetic field. We start by constructing a family of back reacted geometries that include the…
We utilize the effective Lagrangian method within the tree-level Born approximation to explore $\phi$-meson photoproduction, i.e., $\gamma p \to \phi p$. Our analysis encompasses contributions from various sources, including the Pomeron,…
We investigate the $\Lambda(1520)$ photoproduction in the $\vec{\gamma} p \to K^+ \Lambda(1520)$ reaction within the effective Lagrangian method near threshold. In addition to the "background" contributions from the contact, $t-$channel $K$…
By adopting two models of strange and antistrange quark distributions inside nucleon, the light-cone meson-baryon fluctuation model and the effective chiral quark model, we calculate the $D_s^+ - D_s^-$ asymmetry in photoproduction in the…
We study the photo- and electro-productions of the vector kaon off the proton, i.e., $\gamma^{(*)}p\to K^{*+}\pi^0\Sigma^0$, and investigate the line shape of the $\pi^0\Sigma^0$ invariant mass in an effective Lagrangian approach with the…
A model is presented to describe electromagnetically induced two-nucleon emission processes in a shell-model picture. Distortions in the outgoing nucleon waves are accounted for by performing a partial-wave expansion in a real mean-field…
An effective Lagrangian calculation of pion photoproduction including all nucleon resonances up to $\sqrt s = 1.7$ GeV is presented. We compare our results to recent calculations and show the influence of different width parametrizations…
We present Regge-model predictions for the p(gamma,K+)Sigma0 and n(gamma,K+)Sigma- differential cross sections and photon-beam asymmetries in the resonance region. The reaction amplitude encompasses the exchange of K+(494) and K*+(892)…
Partial decay widths of the nucleon resonances $S_{11}(1535)$, $S_{11}(1650)$, $D_{13}(1520)$ and $D_{13}(1700)$ to the pseudoscalar mesons and octet baryons are studied within a chiral constituent quark model. The effects of the…
Recently obtained polarized target and photon asymmetry data in eta photoproduction are shown to be very powerful, in conjunction with the differential cross-section data, in yielding model-insensitive constraints on the electrostrong…
We apply a coupled-channel formalism incorporating quasi-bound quark-model states to calculate pion scattering into eta N, K Lambda and K Sigma channels, as well eta p, eta n, K+Lambda, and K0Sigma+ photo-production processes. The…
A relativistic quark model and a new set of wave functions of nucleon and Delta have been used to study the electromagnetic propertities of (1/2)^+ baryons and photoelectric production of Delta(1236).
A new operator for pion photo- and electroproduction has been developed for nuclear applications at photon equivalent energies up to 1 GeV. The model contains Born terms, vector mesons and nucleon resonances ($P_{33}(1232)$, $P_{11}(1440)$,…
The Roper resonance is described in a chiral version of the chromodielectric model as a cluster of three quarks in radial-orbital configuration (1s)$^2$(2s)$^1$, surrounded by $\pi$ and $\sigma$-meson clouds and by a chromodielectric field…