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Top Friends: Probing Higgs boson associated production with top quarks using the ATLAS detector
Full text linkThe Standard Model (SM) of particle physics represents the leading theoretical framework describing fundamental particles and their interactions. The generation of particle masses is explained via the Brout-Englert-Higgs mechanism, which introduces spontaneous symmetry breaking in the electroweak sector and predicts the existence of a scalar boson, known as the Higgs Boson. The Higgs Boson was experimentally confirmed by both the ATLAS and CMS collaborations at the Large Hadron Collider (LHC), CERN in 2012. The exploration of the Higgs Boson's properties, in particular its interactions with fermions, constitutes a pivotal aspect of the post-Higgs discovery era at the LHC. Among these, measuring Higgs production in association with a pair of top quarks () offers a unique window into the Higgs-top-Yukawa coupling, the largest predicted Yukawa coupling in the SM. Precise measurements of are required to either validate the SM prediction or highlight deviations hinting at possible new physics. This thesis presents a measurement of the production cross-section in the decay channel. The analysis is performed using 140~\text{fb}^{-1}}~of proton-proton collision data at a centre of mass energy of TeV, collected with the ATLAS detector between 2015--2018 at the LHC, corresponding to the full Run 2 dataset. The analysis focuses on events with one or two light charged-leptons in the final state. The development and validation of the profile likelihood fit used to extract the signal cross-section is presented. Neural networks employing attention mechanisms and permutation invariant architectures, known as transformers, perform event classification and reconstruction. Network decisions and potential domain bias levels are studied and presented alongside studies to select the optimal set of observables for the profile likelihood fit. Events in excess of the background-only hypothesis are found, equivalent to an observed (expected) discovery significance of 4.6 (5.4) standard deviations, with a measured cross-section of \sigma_{\ttH} = 411^{+101}_{-92}~\fb = 411 \pm 54~\text{(stat.)}~^{+85}_{-75}~\text{(syst.)} \text{fb}\ ,the most precise individual measurement of production to date. The measurement agrees with the SM prediction. Differential cross-section measurements with respect to the Higgs Boson transverse momentum are also performed within the simplified template cross-section framework. The analysis provides critical precision in the high regime for future combination and Effective field theory (EFT) interpretations
Der Weg von Opfern von Online-Kriminalität durch die britischen Strafverfolgungsbehörden. Translated title: Understanding the journeys of online crime victims through law enforcement in Britain.
Full text linkPeople rely on digital devices to conduct their lives and businesses online, however, the Internet has also enabled traditional crimes committed offline to migrate online, allowing these crimes to be committed transnationally. This creates difficulties for Britain’s law enforcement who have historically worked in forces within geographical boundaries, investigating crimes with offenders and victims at physical locations. Nowadays, victims can be scammed online from across the world and in different jurisdictions. Virtual currency does not require transportation, since it has no physical weight, so perpetrators can attack without moving from their digital devices or leaving physical clues. Victims seek support from law enforcement, support organisations, and social support from friends and family. The journeys of victims of online crime were explored during the main author’s PhD at Royal Holloway, University of London. The study found broken systems, under-reporting and victims taking different journeys depending on whether they are victims of cyber-dependent or cyber-enabled crimes
Women Living with a Traumatic Brain Injury in Prison; Self- and Public Stigma
Full text linkTraumatic brain injury has been referred to as a silent epidemic in correctional services and little is known about how women with traumatic brain injury experience stigma and the possible intersects of this with other aspects of their lives. This study explored the experience of women in prison living with a traumatic brain injury and the impact of internalized/self-stigma and stigma in the prison context (public stigma). Thirteen women in prison took part in semi-structured interviews. Three themes were generated through reflexive thematic analysis. The first two – psychological distress of living with a traumatic braininjury in prison and living in the system with invisible disability – set out contexts of self- and public stigma of traumatic brain injury, intersecting with the stigma of being a woman in prison and with trauma histories relating to injury cause.These are underpinned by the third theme, wanting to be understood. Self-stigma of women in prison with a traumatic brain injury is a barrier to support seeking and intersects with difficulties in talking about the traumatic circumstancesthat led to the injuries. Systemic responses to traumatic brain injury and trauma for women in prison are required to support risk reduction and mental health recovery
Applying Event System Theory to Organizational Change:The Importance of Everyday Positive and Negative Events
Full text linkFinding Safety Violations of AI-Enabled Control Systems through the Lens of Synthesized Proxy Programs
Full text linkBelief in Belief:Even Atheists in Secular Countries Show Intuitive Preferences Favoring Religious Belief
Full text linkWe find evidence of belief in belief – intuitive preferences for religious belief over atheism, even among atheist participants – across 8 comparatively secular countries. Religion is a cross-cultural human universal, yet explicit markers of religiosity have rapidly waned in large parts of the world in recent decades. We explored whether intuitive religious influence lingers, even among nonbelievers in largely secular societies. We adapted a classic experimental philosophy task to test for this intuitive belief in belief among people in eight comparatively nonreligious countries: Canada, China, Czechia, Japan, the Netherlands, Sweden, the UK, and Viet Nam (total N = 3804). Our analyses revealed strong evidence that (1) people intuitively favor religious belief over atheism and that (2) this pattern was not moderated by participants’ own self-reported atheism. Indeed, (3) even atheists in relatively secular societies intuitively prefer belief to atheism. These inferences were robust across different analytic strategies, and across other measures of individual differences in religiosity and religious instruction. Although explicit religious belief has rapidly declined in these countries, it’s possible that belief in belief may still persist. These results speak to the complex psychological and cultural dynamics of secularization
Leveraging Multimodal Shapley Values to Address Multimodal Collapse and Improve Fine-Grained E-Commerce Product Classification
Full text linkMultimodal models can experience multimodal collapse, leading to sub-optimal performance on tasks like fine-grained e-commerce product classification. To address this, we introduce an approach that leverages multimodal Shapley values (MM-SHAP) to quantify the individual contributions of each modality to the model's predictions. By employing weighted stacked ensembles of unimodal and multimodal models, with weights derived from these Shapley values (MM-SHAP), we enhance the overall performance and mitigate the effects of multimodal collapse. Using this approach we improve previous results (F1-score) from 0.67 to 0.79
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