Long-lived Vectors at SHiP with Tao Zhou

Fixed-target experiments are indispensable tools when searching for rare events and feebly interacting particles. I will talk about the production of dark vectors from electromagnetic cascades at the SHiP experiment. The cascades (initiated by photons from π0 → γγ) can lead to 3-4 orders of magnitude increase of the event rate relative to using primary production alone. We provide new SHiP sensitivity projections for dark photons and electrophilic gauge bosons, which are significantly improved compared to previous literature. The main gain in sensitivity occurs for long-lived dark vectors with masses below ∼ 50 − 300 MeV. The dominant production mode in this parameter space is low-energy annihilation e+e− → V (γ). This motivates a detailed study of backgrounds and efficiencies in the SHiP experiment for sub-GeV signals.

This lecture was made possible by the William C. Ferguson Fund.