  We investigate the physics case for a dedicated trigger on a low mass,
hadronic displaced vertex at the high luminosity LHC, relying on the CMS phase
II track trigger. We estimate the trigger efficiency with a simplified
simulation of the CMS track trigger and show that the L1 trigger rate from fake
vertices, B meson decays and secondary interactions with the detector material
can likely be brought down to the kHz level with a minimal set of cuts. While
it would with any doubt be a severe experimental challenge to implement, we
conclude that a displaced vertex trigger could open qualitatively new parameter
space for exotic Higgs decays, exotic B decays and even direct production of
light resonances. We parametrize the physics potential in terms of a singlet
scalar mixing with the Standard Model Higgs and an axion-like particle with a
coupling to gluons, and review a number or relevant models motivated by the
hierarchy and strong CP problems, dark matter and baryogenesis.
