Searching for muonphilic dark sectors with proton beams

Proton beam-dump experiments are a high-intensity source of secondary muons and provide an opportunity to probe muon-specific dark sectors. We adopt simplified-models framework for exotic light scalar particle coupling predominantly or exclusively muons. Equipped with state-of-the-art muon simulations, we compute the sensitivity reach in parameter space $({m}_{S},{g}_{\ensuremath{\mu}})$ mediator, examining detail examples experiment NA62 mode proposed SHiP. find significant yield such exotics sub-GeV mass range. Our projections competitive those primary muon-beam complementary current constraints, spanning uncharted accessing new physics potentially responsible $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ anomaly.