CMS Hardware Track Trigger: New Opportunities for Long-Lived Particle Searches at the HL-LHC

Abstract: The planned upgrade of the CMS detector for the High Luminosity LHC allows to find tracks in the silicon tracker for every single LHC collision and use them in the first level (hardware) trigger decision. So far, studies by CMS collaboration concentrated on the maintaining the overall trigger performance in the punishing pile up environment. We argue that the potential capabilities of the track trigger are much wider, and may offer groundbreaking opportunities for new physics searches. As an example, and to facilitate community discussion, we use a simple toy simulation to study rare Higgs decays into new particles with lifetime of order of a few mm.