Electroproduction of $Λ(1520)$ off the nucleon target with the nucleon resonances

Abstract

We investigate the unpolarized electroproduction of $Λ(1520)\equivΛ^*$ off the nucleon target, using the effective Lagrangian method at the tree-level Born approximation with the nucleon-resonance contributions from $S_{11}(2090)$, $D_{13}(2080)$, and $D_{15}(2200)$. First, we compute the various physical quantities for the proton target case, such as the total and differential cross sections, $t$-momentum transfer distribution, and $K^-$ decay-angle ($ϕ$) distribution. It turns out that $D_{13}$ plays an important role to reproduce the electroproduction data properly. The numerical results for the $ϕ$ distribution shows obvious different structures from that for the photoproduction, due to the enhancement of the kaon exchange by the longitudinal polarization of the virtual photon as expected. Numerically, we observe that the kaon-exchange contribution in the $t$ channel becomes about a half of that from the contact-term one that dominates the photoproduction of $Λ^*$. We also provide theoretical estimations for the $Λ^*$ electroproduction off the neutron target, showing that its production rate is saturated almost by the resonance contributions. Finally, the contact-term dominance, which is the key ingredient for the $Λ^*$ electromagnetic productions, is briefly discussed.