| 2. |
- Alimena, Juliette, et al.
(författare)
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Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider
- 2020
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 47:9
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Zurita-Altamirano, D., et al.
(författare)
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The Allemann collection from the Santa Cruz Formation (late early Miocene), Argentina, in Zurich, Switzerland
- 2019
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Ingår i: Swiss Journal of Palaeontology. - : Springer Science and Business Media LLC. - 1664-2376 .- 1664-2384. ; 138:2, s. 259-275
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Tidskriftsartikel (refereegranskat)abstract
- One of the best-known faunal assemblages that characterizes the past ecosystems from South America comes from the Santa Cruz Formation in Argentina. This assemblage is formed by an endemic fauna, which included ground sloths, glyptodonts, native ungulates, terror birds (phorusrhacids), among others. The Santacrucian South American Land Mammal Age is dated 18.0-15.6 Ma, late early Miocene. Current curatorial efforts revealed a large collection of over 1100 fossil remains from the Santa Cruz Formation, donated in 2007 to the Paleontological Museum, University of Zurich, Switzerland. The fossils were brought to Switzerland in the late 1880s by Theodor Allemann, an engineer and amateur collector. The collection includes skulls, isolated teeth, mandibles, and isolated postcranial elements. Postcranials are mainly represented by astragali, calcanei, and osteoderms. The study of the remains allowed us to recognize 20 families of mammals, one of birds, and one of amphibians: Abderitidae, Palaeothentidae (Paucituberculata); Hathliacynidae (Sparassodonta); Dasypodidae, Peltephilidae, and Glyptodontidae (Cingulata); Megatheriidae and Megalonychidae (Tardigrada); Astrapotheriidae (Astrapotheria), Protherotheriidae and Macraucheniidae (Litopterna); Toxodontidae, Homalodotheriidae, Hegetotheriidae and Interatheriidae (Notoungulata); Dasyproctidae, Dinomyidae, Neoepiblemidae, Chinchillidae, Erethizontidae, Echimyidae and Eocardidae (Rodentia); Phorusrhacidae (Cariamiformes); and Calyptocephalellidae (Anura). Among them, we identified 28 genera and 9 species. Reference to the previous work on the Santa Cruz fauna and the good preservation of the material allow us to achieve taxonomic resolution in the identifications. We discuss the potential usefulness of this collection for studying the paleobiology of specimens/species of this fauna.
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