Gerasimov-Drell-Hearn Sum Rule and the Discrepancy between the New CLAS and SAPHIR Data

Contribution of the K^+\Lambda channel to the Gerasimov-Drell-Hearn (GDH) sum rule has been calculated by using the models that fit the recent SAPHIR or CLAS differential cross section data. It is shown that the two data sets yield quite different contributions. Contribution of this channel to the forward spin polarizability of the proton has been also calculated. It is also shown that the inclusion of the recent CLAS C_x and C_z data in the fitting data base does not significantly change the result of the present calculation. Results of the fit, however, reveal the role of the S_{11}(1650), P_{11}(1710), P_{13}(1720), and P_{13}(1900) resonances for the description of the C_x and C_z data. A brief discussion on the importance of these resonances is given. Measurements of the polarized total cross section \sigma_{TT'} by the CLAS, LEPS, and MAMI collaborations are expected to verify this finding.Comment: 15 pages, 8 figure

Kaon photoproduction on the nucleon: overview of some applications

Some applications of the elementary kaon photoproduction process are discussed: the investigation of missing resonances in the p(gamma,K+)Lambda channel, the role of the P_{13}(1720) state in the p(gamma,K0)Sigma+ channel, and the calculation of the Gerasimov-Drell-Hearn sum rule. For the latter, we present an extension of our previous study to higher energies.Comment: 3 pages, contribution to FB2000 (Taiwan) March 2000, to be published in Nucl. Phys.

Role of the K1K_1 meson in K0K^0 photoproduction off the deuteron

Neutral kaon photoproduction off the nucleon and deuteron has been reinvestigated by utilizing the new experimental data on both targets. An isobar model for elementary operator and impulse approximation for the reaction on the deuteron have been used. The available free parameters in the elementary model have been extracted from both elementary and deuteron data. In contrast to the elementary reaction, fitting the deuteron data requires an inclusion of weighting factor. The result indicates that the angular distribution of the elementary $K^0\Lambda$ process does not show backward peaking behavior.Comment: 4 pages, 4 figures, prepared for the Fifth Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011), Seoul, Korea, August 22-26, 201

Kaon photoproduction on the nucleon: Contributions of kaon-hyperon final states to the magnetic moment of the nucleon

By using the Gerasimov-Drell-Hearn (GDH) sum rule and an isobaric model of kaon photoproduction, we calculate contributions of kaon-hyperon final states to the magnetic moment of the proton and the neutron. We find that the contributions are small. The approximation of sigma_{TT'} by sigma_{T} clearly overestimates the value of the GDH integral. We find a smaller upper bound for the contributions of kaon-hyperon final states to the proton's anomalous magnetic moment in kaon photoproduction, and a positive contribution for the square of the neutron's magnetic moment.Comment: 6 pages, revtex, 1 postscript figure, to appear in Phys. Rev.

Dynamical coupled-channel approach to hadronic and electromagnetic production of kaon-hyperon on the proton

A dynamical coupled-channel formalism for processes $\pi N \to KY$ and $\gamma N \to KY$ is presented which provides a comprehensive investigation of recent data on the $\gamma p \to K^+ \Lambda$ reaction. The non-resonant interactions within the subspace $KY\oplus\pi N$ are derived from effective Lagrangians, using a unitary transformation method. The calculations of photoproduction amplitudes are simplified by casting the coupled-channel equations into a form such that the empirical $\gamma N \to \pi N$ amplitudes are input and only the parameters associated with the $KY$ channel are determined by performing $\chi^2$-fits to all of the available data for $\pi^- p \to K^\circ\Lambda, K^\circ\Sigma^\circ$ and $\gamma p \to K^+\Lambda$. Good agreement between our models and those data are obtained. In the fits to $\pi N \to KY$ channels, most of the parameters are constrained within $\pm 20$ of the values given by the Particle Data Group and/or quark model predictions, while for $\gamma p \to K^+ \Lambda$ parameters, ranges compatible with broken $SU(6)\otimes O(3)$ symmetry are imposed. The main reaction mechanisms in $K^+ \Lambda$ photoproduction are singled out and issues related to newly suggested resonances $S_{11}$, $P_{13}$, and $D_{13}$ are studied. Results illustrating the importance of using a coupled-channel treatment are reported. Meson cloud effects on the $\gamma N \to N^*$ transitions are also discussed.Comment: Accepted Physical Review