1,721,021 research outputs found
TOP QUARK PHYSICS AT THE TEVATRON
Get PDFThe heaviest known elementary particle, the top quark, was discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton-antiproton collider at Fermilab. Since its discovery, a large program was set in motion by the CDF and D0 collaborations to characterize the production and decay properties of top quarks, and investigate their potential for searches of new phenomena beyond the standard model. During the past 20 years, new methods were developed and implemented to improve the measurements and searches for new physics in the top quark sector. This paper reviews the achievements and results obtained through studies of the top quark at the Tevatron.Helmholtz Associatio
Observation of four top quarks production and EFT interpretations in the multi-lepton final state with the ATLAS Experiment
Get PDFThe Standard Model has been remarkably successful in describing fundamental particles and their interactions. However its incompleteness makes the search for physics beyond the Standard Model one of the most important challenges in particle physics. One promising avenue for uncovering potential deviations from the Standard Model is through the study of rare processes in multi-lepton final states, which offer a rare and distinct signal with manageable backgrounds from Standard Model processes. This thesis presents a comprehensive study of top-quark production and interactions in proton-proton collisions, focusing on the observation of four-top-quark () production and interpretations using the framework of Effective Field Theory.
The analyses are performed using data corresponding to an integrated luminosity of 140 fb at a centre-of-mass energy of 13 TeV, recorded by the ATLAS experiment at the Large Hadron Collider. Events with two same-sign leptons or at least three leptons (electrons or muons) are selected. Through the use of multivariate techniques and control regions to constrain backgrounds, the production cross section is measured to be fb, consistent with the Standard Model prediction within 1.8 standard deviations. This thesis also explores the Standard Model Effective Field Theory (SMEFT) interpretation of the measurement of top quark production in association with a boson using the same data and final states. The study is based on the recent cross-section measurement by ATLAS which confirms an excess in like events consistent with several previous results. Limits are extracted on the Wilson Coefficients of 21 SMEFT operators using detector-level profile likelihood fits.2025-04-0
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
HL/HE-LHC physics prospectives in top quark physics
No full textThe talk presents the HL-LHC and HE-LHC prospects for top physics
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Four-top quark production in ATLAS
No full textSlides for the talk: Top physics highlights from ATLAS at MoriondQCD 202
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