Role of a triangle singularity in the γ p → K+Λ(1405) reaction

摘要

We show the effects of a triangle singularity mechanism for the γp → K+Λ(1405) reaction. The mechanism has a N* resonance around 2030 MeV, which decays into K*Σ. The K* decays to K+π, and the πΣ merge to form the Λ(1405). This mechanism produces a peak around s~(1/2) = 2110 MeV, and has its largest contribution around cosθ = 0. The addition of this mechanism to other conventional ones leads to a good reproduction of dσ/dcosθ and the integrated cross section around this energy, providing a solution to a problem encountered in previous theoretical models.