A new generation of dark matter experiments focusing on sub-GeV Dark Sectors capable of explaining the observed relic abundance have attracted increasing interest over the last decade. One of the most general models with a sub-GeV mediator is a Dark Sector which introduces a new U(1) gauge symmetry, with a corresponding boson called a "dark photon", "heavy photon", or A' (read A prime). The Heavy Photon Search (HPS) is one of the first experiments dedicated to the search for dark photons, specifically in the case that they decay to standard model charged leptons. HPS has successfully completed two physics runs in 2019 and 2021. I will present the status of an analysis for a Dark Sector that includes an additional SU(3) gauge symmetry in addition to the extra U(1), also known as a SIMP model. Meanwhile, a recently proposed project called the Light Dark Matter eXperiment (LDMX) will be sensitive to the production of sub-GeV dark matter particles, such as those with interactions mediated by dark photons. The LDMX detector concept, its rejection of key backgrounds, and sensitivity to new physics will be presented.
David Charles Goldfinger, Zhi Zheng
(dgoldfinger@stanford.edu, zzheng@slac)
