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Abstract Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton–proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments—as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER—to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity ‘dark showers’, highlighting opportunities for expanding the LHC reach for these signals.
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Results from commissioning and/or prototypes for new small (HL-)LHC experiments
To the surprise of many physicists, no beyond Standard Model particles have been discovered so far at the Large Hadron Collider (LHC). Hence, the search efforts for physics beyond the Standard Model have to be significantly broadened and extended also towards smaller experiments. In this short review, selected results from the commissioning and prototype development of multiple new small-scale experiments at the LHC are presented. The focus is set on the latest results from the FASER experiment, as well as a short overview of the progress of the SND@LHC, MATHUSLA and milliQan experiments.
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- PAR ID:
- 10339506
- Date Published:
- Journal Name:
- The Ninth Annual Conference on Large Hadron Collider Physics (LHCP2021)
- Page Range / eLocation ID:
- 320
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.22323/1.397.0320
