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

摘要

We investigate the unpolarized electroproduction of Λ(1520) ≡ Λ* off the nucleon target, using the effective Lagrangian method at the tree-level Born approximation with nucleon-resonance contributions from S_(11)(2090), D_(13)(2080) and D_(15)(2200). First, we compute 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 in reproducing the electroproduction data properly. The numerical results for the φ distribution show obvious different structures 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 is about half 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 almost saturated by resonance contributions. Finally, the contact-term dominance, which is the key ingredient for Λ* electromagnetic productions, is briefly discussed.