Photoproduction of $\Lambda (1405)$ with the $N^{\ast }$ and $t$-channel Regge contributions

Abstract

We investigate the photoproduction of $\Lambda (1405)\equiv {\Lambda }^{\ast }$ hyperon resonance, i.e., $\gamma p\to K^{+}{\Lambda }^{\ast }$, employing the effective Lagrangian approach with the $t$-channel Regge trajectories at tree level. We extensively explore the effects from the nucleon resonances in the vicinity of the threshold ${\sqrt{s}}_{\mathrm{th}}\approx 1900$ MeV, i.e., $N(2000)$, $N(2030)$, $N(2055)$, $N(2095)$, and $N(2100)$, and observe that they are of great importance to reproduce the recent CLAS/Jlab experimental data. Total and differential cross sections are given as numerical results and compared with the experimental data, in addition to the $t$-channel momentum transfer and photon-beam asymmetry. The invariant-mass plots for $\gamma p\to K^{+}{\pi }^0{\Sigma }^0$ via ${\Lambda }^{\ast }$ are also extracted from the two-body process results, showing a qualitative agreement with the data. We also discuss the constituent-counting rule for the internal structure of ${\Lambda }^{\ast }$, resulting in that ${\Lambda }^{\ast }$ appears to be different from a simple three-quark $(uds)$ state.

Comments: 15 pages, 9 figures