It is widely recognized that the Standard Model (SM) of particle physics is not a complete description of the interactions of fundamental particles. And yet, after over a decade of intense scrutiny, the experiments at the Large Hadron Collider (LHC) have produced no definitive evidence of physics beyond the SM. The vast majority of searches for beyond SM physics have targeted heavy, strongly interacting particles that decay almost instantaneously back to SM particles. However, many models propose the existence of new long-lived particles (LLPs) that can travel significant distances before decaying, yielding unconventional detector signatures that may be overlooked by common search techniques. Searches for LLPs decaying in the ATLAS inner detector (ID) are crucial for providing experimental sensitivity to a broad range of LLP lifetimes, but also must overcome challenges posed by the reconstruction of displaced charged particle trajectories (tracks). Recently, breakthroughs in ATLAS track reconstruction have revolutionized the inner tracking detector's ability to identify LLP decays and invigorated the ATLAS LLP search program. In this seminar, I will highlight the recent advancements in displaced track reconstruction and present the latest search results for LLP decays in the ATLAS ID. Additionally, I will discuss prospects for expanding the LLP search program at the High Luminosity LHC through further innovation in track reconstruction, and explain why there is reason to be optimistic about the future of particle physics at the LHC.
