UWCScholar
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Recent Submissions
Test of lepton flavour universality in W-boson decays into electrons and τ-leptons using pp collisions at = 13 TeV with the ATLAS detector
(Springer Science and Business Media Deutschland GmbH, 2025) Leeuw, Lerothodi; Aad, Georges; Aakvaag, Erlend
A measurement of the ratio of the branching fractions, Rτ/e = B(W → τν)/B(W → eν), is performed using a sample of W bosons originating from top-quark decays to final states containing τ-leptons or electrons. This measurement uses pp collisions at = 13 TeV, collected by the ATLAS experiment at the Large Hadron Collider during Run 2, corresponding to an integrated luminosity of 140 fb−1. The W → τντ (with τ → eνeντ) and W → eνe decays are distinguished using the differences in the impact parameter distributions and transverse momentum spectra of the electrons. The measured ratio of branching fractions Rτ/e = 0.975 ± 0.012 (stat.) ± 0.020 (syst.), is consistent with the Standard Model assumption of lepton flavour universality in W-boson decays.
A review and comparison of methods of parameter estimation and inference for heteroskedastic linear regression models
(Taylor and Francis Ltd., 2025) Farrar, Thomas J.; Blignaut, Rénette Julia; Luus, Retha; Steel, Sarel J.
This article reviews methods of parameter estimation and inference in the linear regression model under heteroskedasticity. Several approaches to feasible weighted least squares estimation of the parameter vector are reviewed, along with various heteroskedasticity-consistent covariance matrix estimators, which are usually designed with inference as the end goal. A Monte Carlo experiment is designed to evaluate the ability of the reviewed methods to estimate three quantities: the variances of the random errors, the parameter vector, and the standard error of the ordinary least squares estimator thereof. Results of the experiment show that the homoskedastic variance estimator performs well at estimating error variances even in the heteroskedastic data-generating processes studied. Feasible weighted least squares approaches perform best for estimation of the parameter vector, whereas heteroskedasticity-consistent covariance matrix estimators perform best for estimation of the standard error thereof. This motivates a search for a method that would perform well in all three respects.
Trauma exposure, insomnia, and fatigue: a cross‐sectional study of the pathways to burnout among South African first responders
(John Wiley & Sons, Inc, 2025) Padmanabhanunni, Anita; Pretorius, Tyrone
Background and Aims: First responders are disproportionately vulnerable to the development of insomnia, fatigue and burnout, due to chronic exposure to trauma inherent in their occupational roles. This study examined the mediating roles of insomnia and fatigue in the relationship between trauma exposure and burnout among South African first responders. Methods: Participants included police officers (n = 309) and paramedics (n = 120) in the Western Cape province of South Africa. They completed an online survey comprising the Life Events Checklist, the Insomnia Severity Index, the Chalder Fatigue Questionnaire, and the Maslach Burnout Inventory. Mediation analyses were conducted using the Hayes PROCESS macro in SPSS Version 30.Results: Mediation analysis provided evidence of both parallel as well as serial mediation roles for insomnia and fatigue in the relationship between trauma exposure and burnout. Insomnia fully mediated the relationships between trauma exposure and emotional exhaustion as well as personal accomplishment and partially mediated the relationship with depersonalization. Fatigue fully mediated the relationships between trauma exposure and emotional exhaustion and depersonalization but did not mediate the relationship with personal accomplishment. Serial mediation analysis indicated that insomnia and fatigue, in sequence, fully mediated the effects of trauma exposure on emotional exhaustion and depersonalization. Conclusions: Insomnia and fatigue are critical pathways linking trauma exposure to burnout among South African first responders. Early identification and treatment of sleep disturbances may be crucial for preventing burnout and enhancing resilience in this population.
Euclid preparation LXIII. Simulations and non-linearities beyond Lambda cold dark matter. 2. Results from non-standard simulations
(EDP Sciences, 2025) Karagiannis, Dionysis
The Euclid mission will measure cosmological parameters with unprecedented precision. To distinguish between cosmological models, it is essential to generate realistic mock observables from cosmological simulations that were run in both the standard Λ-cold-dark-matter (ΛCDM) paradigm and in many non-standard models beyond ΛCDM. We present the scientific results from a suite of cosmological N-body simulations using non-standard models including dynamical dark energy, k-essence, interacting dark energy, modified gravity, massive neutrinos, and primordial non-Gaussianities. We investigate how these models affect the large-scale-structure formation and evolution in addition to providing synthetic observables that can be used to test and constrain these models with Euclid data. We developed a custom pipeline based on the Rockstar halo finder and the nbodykit large-scale structure toolkit to analyse the particle output of non-standard simulations and generate mock observables such as halo and void catalogues, mass density fields, and power spectra in a consistent way. We compare these observables with those from the standard ΛCDM model and quantify the deviations. We find that non-standard cosmological models can leave large imprints on the synthetic observables that we have generated. Our results demonstrate that non-standard cosmological N-body simulations provide valuable insights into the physics of dark energy and dark matter, which is essential to maximising the scientific return of Euclid.
Editorial – ‘asking for the moon’: a special issue on Drucilla Cornell
(Springer Science and Business Media B.V., 2025) van Marle, Karin
Several tributes and publications have appeared since Drucilla Cornell’s untimely passing on the 22 December 2022. The birth of this special issue commemorating her was a stream organised at the Critical Legal Conference that took place at the University of Durham in September 2023. Not all of the papers delivered at the conference were submitted for this issue and one of the articles published here was not delivered at the conference but the issue nevertheless reflects the spirit and gist of a gathering of people who worked closely with Drucilla, her ideas, politics and theories honouring her memory and legacy.