Speaker
Dr
Aichao Wang
(University of Chinese Academy of Sciences)
Description
The high-precision differential cross-section data for the reaction gamma p -> K* Lambda are re-analyzed within a Regge-inspired effective Lagrangian approach. The model adopts Regge phenomenology to constrain the t-channel contributions from the kappa, K and K* exchanges. A minimum number of resonances in the s-channel are introduced in constructing the reaction amplitudes in order to describe the data. With the purpose of testing how strongly the reaction mechanism, the extracted resonance contents and the associated resonance parameters depend on the way that the t-channel meson-exchange amplitudes are constructed. It is shown that in both Regge model and the interpolated Regge model, the differential cross-section data for gamma p -> K* Lambda can be satisfactorily described by introducing the only N(2060)5/2- resonance in the s channel, which is quite different from our earlier work performed in an effective Lagrangian approach [A. C. Wang et al., Phys.Rev. C 96, 035206 (2017)], where the amplitudes are computed by evaluating Feynman diagrams and it was found that introducing at least one additional resonance apart from the N(2060)5/2- is indispensable for reproducing the data.
The reaction mechanisms are found to be highly model dependent. In the near threshold region, especially at the center-of-mass energy W = 2041 MeV, the angular distributions are dominated by the K exchange in the Regge model, by the N(2060)5/2- exchange in the interpolated Regge model, and by both the K exchange and N(2060)5/2- exchange in the Feynman model of our previous work. At higher energies, the angular distributions are found to be dominated by the K and N(2060)5/2- exchanges in the Regge model, by the N(2060)5/2- exchange in the interpolated Regge model, and by the K, N(2060)5/2- and the other resonance exchanges in the Feynman model. The K exchange, which plays a very significant role in almost the whole energy range considered in both the Regge model and the Feynman model, provides rather small contributions in the interpolated Regge model. On the contrary, the K* exchange and the interaction current, which are negligible in both the Regge model and the Feynman model, offers considerable contributions in the interpolated Regge model. So one can get the conclusion that with only the differential cross sections available for experimental data, the extracted resonance contents are strongly model depended and further study need take the spin observable data into account.
Primary authors
Dr
Aichao Wang
(University of Chinese Academy of Sciences)
Prof.
Fei Huang
(University of Chinese Academy of Sciences)
