Role of $\Lambda(1670)$ in the $\gamma p \to K^+ \eta \Lambda $ reaction near threshold

Abstract

The role of the $\Lambda(1670)$ resonance in the $\gamma p \to K^+ \eta \Lambda$ reaction near threshold is studied within an effective Lagrangian approach. We perform a calculation for the total and differential cross section of the $\gamma p \to K^+ \eta \Lambda$ reaction by including the contributions from the $\Lambda(1670)$ intermediate state decaying into $\eta \Lambda$ dominated by $K^-$ and $K^{*-}$ mesons exchanges, the nucleon pole and $N^*(1535)$ resonance decaying into $K^+ \Lambda$ dominated by exchanges of $\omega$ and $K^-$ mesons. Besides, the non-resonance process and contact terms to keep the total scattering amplitude gauge invariant are also considered. With our model parameters, the total cross section of this reaction is of the order of $1$ nanobarn at photon beam energy $E_{\gamma} \sim 2.5$ GeV. It is expected that our model predictions could be tested by future experiments.