Partial wave analysis for KΣ photoproduction on the nucleon valid from threshold up to W = 2.8 GeV

Abstract

We have simultaneously analyzed the available kaon photoproduction data for the , , , and channels by using an isobar model constructed from the Feynman diagrammatic approach for the background terms and multipoles formulation for the resonance terms. The unknown coupling constants in the background terms as well as the helicity amplitudes and the kaon branching ratios of the resonance terms were extracted by fitting the calculated observables to nearly 8000 data points from the latest experimental measurements, including the recent and data from MAMI A2 collaboration. During the fitting process we used the data listed in the Review of Particle Properties of Particle Data Group as a guidance for the resonance properties. Since in the previous study the kaon branching ratio of the N(1710)P11 state was found to be relatively large and, as a consequence, a sizable spike appeared in the K+Σ− cross section near the threshold, in the present work we propose two isobar models, i.e. with and without this state. We have found that both models can nicely fit the data. Extensive comparisons between the result of model calculation and experimental data are presented in this paper. To investigate the role of each resonance in the present work the significance of each resonance is calculated and discussed. The present work indicates that the N(1895)S11 and Δ(1900)S31 as the important resonances in the KΣ photoproduction. We also present two examples of application of the presented isobar models, i.e. investigation of the nucleon resonance N(1535)S11 coupling to the KΣ channels and the contribution of KΣ channels to the Gerasimov–Drell–Hearn sum rule.

Model selection forK+Σ−photoproduction within an isobar model

“…This state was found to be the most significant one in Ref. [7]. We see, therefore, that the results of our single-channel analysis are in a very good agreement with the results of a multichannel analysis.…”

“…An important effect of this resonance was also observed in the K 0 + channel [26] and in the combined analysis of all channels performed in Ref. [7]. We also note a significant contribution of the N (1895) 1/2 − state with a relatively large K branching ratio.…”

“…This state was found in Ref. [7] to be among the most significant states for dynamics in the K channels. The role of the (1900) 1/2 − resonance is in modeling the peak in the cross-section data, but it slightly modifies the beam asymmetry description as well.…”

“…The K photoproduction channels were also studied, but, similarly to the case of the K + channel, only after 2004 could these studies be based on more good-quality data, mainly due to the data in the resonance region of the K + 0 channel from the CEBAF, ELSA, MAMI (University in Mainz), and SPring-8 (Japan) facilities; see, e.g., Ref. [7] and references therein. However, data in the other channels with the hyperon are still quite scarce in comparison with the number of data in the K + and K + 0 channels; see in a recent overview by Ireland, Pasyuk, and Strakovsky [8].…”

“…A combined analysis of all four channels with was performed by Mart and Kholili in Ref. [7]. The background part of the amplitude was constructed using an isobar model and the resonant part using a multipole formulation.…”