Sensitivity to decays of long-lived dark photons at the ILC (A Snowmass White Paper)

Abstract: We investigate the sensitivity to long-lived dark photons produced in Higgstrahlung events via the Higgs portal, $H \rightarrow \gamma_{D} \gamma_{D}$, with the Silicon Detector (SiD) at the International Linear Collider (ILC). These events provide a useful benchmark for tracking and vertex detector performance with long-lived particle decays at displaced vertices. The ILC is one of several Higgs factories proposed by the international community to study the properties of the Higgs boson at high precision.