Accuracy versus precision in boosted top tagging with the ATLAS detector

Abstract The identification of top quark decays where the top quark has a large momentum transverse to the beam axis, known as top tagging, is a crucial component in many measurements of Standard Model processes and searches for beyond the Standard Model physics at the Large Hadron Collider. Machine learning techniques have improved the performance of top tagging algorithms, but the size of the systematic uncertainties for all proposed algorithms has not been systematically studied. This paper presents the performance of several machine learning based top tagging algorithms on a dataset constructed from simulated proton-proton collision events measured with the ATLAS detector at √ s = 13 TeV. The systematic uncertainties associated with these algorithms are estimated through an approximate procedure that is not meant to be used in a physics analysis, but is appropriate for the level of precision required for this study. The most performant algorithms are found to have the largest uncertainties, motivating the development of methods to reduce these uncertainties without compromising performance. To enable such efforts in the wider scientific community, the datasets used in this paper are made publicly available.</jats:p

The CMS Statistical Analysis and Combination Tool: Combine

Metrics: https://link.springer.com/article/10.1007/s41781-024-00121-4/metricsThis paper describes the Combine software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run Combine and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of Combine. However, the online documentation referenced within this paper provides an up-to-date and complete user guide.CERN (European Organization for Nuclear Research)STFC (United Kingdom)Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 724704, 752730, 758316, 765710, 824093, 101115353, 101002207, and COST Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundatio

Constructing regionalism in South America : the cases of transport infrastructure and energy within UNASUR

This paper seeks to contribute to the study of contemporary South American regionalism focusing on the emergence and development of sectoral cooperation and policy coordination within the Union of South American Countries (UNASUR). To do so the paper analyzes two policy areas 'transport infrastructure and energy integration' from the inception of cooperation in 2000 until 2014, addressing two questions: (i) why regional cooperation has emerged despite the absence of economic interdependence and market-driven demand for economic integration, and (ii) why policy outcomes are evident in some areas (i.e., transport infrastructure) while limited in others (i.e., energy). Bringing together insights from rationalist and constructivist approaches in IR and IPE, it is argued that the emergence of regional cooperation as well as the sharp variation in policy outcomes between areas can be largely explained by the articulation of a regional leadership and its effect on the convergence of state preferences. The paper shows how the Brazilian leadership, incentivized by the effects of the US-led FTAA negotiations and the financial crises that hit the region in the late 1990s, made state preferences converge towards a regionalist project encompassing all South American countries by making visible the mutual benefits of cooperation on transport infrastructure and energy. Furthermore, the paper illustrates how in spite of significant changes in South American states’ cooperation preferences the Brazilian leadership was able to adapt the cooperation process in the transport infrastructure sector to the new circumstances of regional politics permitting not only the institutionalization of sectoral cooperation, but also the implementation of several infrastructure transnational projects. In the case of energy, instead, the emergence of a second regional leadership project – pursued by Chávez’s Venezuela – and the deep divergence of state preferences led energy cooperation into a gridlock

Facet-controlled synthesis and morphological evolution of Cu₂O microcrystals

Cu2O microcrystals were prepared through reduction of Cu2+ ions by glucose in an alkaline aqueous solution.</jats:p