Low-energy Nϕ scattering from a pole-enhanced triangle diagram

We investigate low-energy Nϕ scattering driven by a pole-enhanced triangle-like diagram, in which the two-Kaon-exchange contribution is promoted by the near-threshold Λ(1405) pole in the N K ¯ subsystem. Using an unphysical Kaon mass motivated by lattice simulations, we evaluate the Nϕ scattering length and find that this mechanism generates an attractive interaction with a magnitude of − 1.1 to − 0.5 fm . Spin-dependent effects are not treated explicitly and are expected to provide subleading corrections in the near-threshold region. We further analyze the low-energy behavior of the triangle-like diagram amplitude and show that the scattering length depends on the parameter δ , defined as the mass difference between the K K ¯ threshold and the ϕ meson, and the pole position of Λ(1405), where the Λ(1405) plays a crucial role to understand Nϕ interaction. Furthermore, by employing physical hadron masses, our calculated scattering length is found to be consistent with current experimental data, providing a unified description across both unphysical and physical mass regimes. This type of interaction differs from that associated with van der Waals-type forces or the long-range tail of two-pion exchange, highlighting the role of three-body dynamics encoded in the pole-enhanced triangle-like diagram in shaping the near-threshold Nϕ interaction.