Speaker: David Curtin
Searches for long-lived particles (LLPs) at the LHC are broadly motivated in almost any BSM scenario that addresses one or more of the long-standing puzzles of high energy physics. I will focus on some recent theory developments in Neutral Naturalness to motivate study of exotic Higgs decays to LLPs, the production and annihilation of quirkonia into Emerging-Jet-like final states, and additional cosmological probes. The LLP signature space is as big as the space of prompt searches, and is just starting to be explored. In particular, very long and very short lifetimes have not yet been adequately studied. I outline how such signatures can be looked for at the LHC, and advocate for the construction of a dedicated surface detector called MATHUSLA for the HL-LHC upgrade.