The Search for Dark Photons at the Short Baseline Near Detector

A plethora of astronomical and cosmological observations have provided strong evidence for the existence of dark matter. Many experiments throughout the globe, as such, have made efforts to probe this dark sector of particle physics, from large collider experiments like the Large Hadron Collider (LHC), to medium scale fixed target experiments demonstrated in the Short Baseline Neutrino Program (SBN). In recent years, light dark sector particles -- such as dark photons -- have gained significant attention as candidates for physics beyond the Standard Model (BSM). These particles arise in well-motivated extensions involving a hidden U(1) gauge symmetry and can couple to Standard Model (SM) particles through kinetic mixing. This work investigates the production of these dark-sector states at the Booster Neutrino Beam (BNB) when the 8 GeV protons hit the BNB target and the downstream dump, and their detection at the Short-Baseline Near Detector (SBND). We explore how neutral mesons like π₀ and η generate dark photons via two-body decays as well as through bremsstrahlung radiation during proton beam interactions with the target and the dump. At SBND, we focus on detecting dark photons through electron-positron pair decay channels. We investigate both the potential for various analysis tools to be employed in a Dark Photon search, and how they contribute to an enhanced sensitivity.