| 1. |
- 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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| 2. |
- Breznau, Nate, et al.
(författare)
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Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:44
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Tidskriftsartikel (refereegranskat)abstract
- This study explores how researchers analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each teams workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.
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| 3. |
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| 4. |
- Heisig, Jan, et al.
(författare)
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Dark matter or correlated errors : Systematics of the AMS-02 antiproton excess
- 2020
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Ingår i: Physical Review Research. - 2643-1564. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have pointed out an excess in the AMS-02 antiproton spectrum at rigidities of 10–20 GV. Its spectral properties were found to be consistent with a dark-matter particle of mass 50–100 GeV which annihilates hadronically at roughly the thermal rate. In this paper, we reinvestigate the antiproton excess, including all relevant sources of systematic errors. Most importantly, we perform a realistic estimate of the correlations in the AMS-02 systematic error which could potentially “fake” a dark-matter signal. The dominant systematics in the relevant rigidity range originate from uncertainties in the cross sections for absorption of cosmic rays within the detector material. We calculate their correlations within the Glauber-Gribov theory of inelastic scattering. The AMS-02 correlations enter our spectral search for dark matter in the form of covariance matrices, which we make publicly available for the cosmic-ray community. We find that the global significance of the antiproton excess is reduced to below 1 σ once all systematics, including the derived AMS-02 error correlations, are taken into account. No significant preference for a dark-matter signal in the AMS-02 antiproton data is found in the mass range 10–10 000 GeV.
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| 5. |
- Heisig, P., et al.
(författare)
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A Generic Traceability Metamodel for Enabling Unified End-to-End Traceability in Software Product Lines
- 2019
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Ingår i: SAC '19 Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing. - New York, NY, USA : ACM Digital Library. - 9781450359337
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Bokkapitel (refereegranskat)abstract
- Mature development methodologies like software product line engineering or model-driven engineering are more and more adopted in software development. Accordingly, the resulting development processes combine artifacts from different disciplines and on different abstraction levels. It is crucial that the relationship between these artifacts is explicitly maintained to be able to track the development process and the reasons for design decisions. This problem becomes exacerbated if variability is considered since it is a cross-cutting concern that impacts all disciplines and artifacts. Traceability links support the linking of artifacts across model boundaries in an end-to-end manner. However, existing traceability solutions are either limited to specific development processes, tools, and artifact types, lack in uniformity, or do not consider variability. Thus, this paper introduces a MOF-based generic traceability metamodel for establishing uniform traceability-enabled workflows in a variability-aware and model-based environment. Necessary steps for instantiating the metamodel to specific artifact types of certain development processes are described. We evaluate the proposed solution with an exemplar of a car headlight and demonstrate the benefits of a consistent traceability concept.
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